TWI288479B - Bipolar transistor with graded base layer - Google Patents

Abstract

A semiconductor material which has a high carbon dopant concentration includes gallium, indium, arsenic and nitrogen. The disclosed semiconductor materials have a low sheet resistivity because of the high carbon dopant concentrations obtained. The material can be the base layer of gallium arsenide-based heterojunction bipolar transistors and can be lattice-matched to gallium arsenide emitter and/or collector layers by controlling concentrations of indium and nitrogen in the base layer. The base layer can have a graded band gap that is formed by changing the flow rates during deposition of III and V additive elements employed to reduce band gap relative to different III-V elements that represent the bulk of the layer. The flow rates of the III and V additive elements maintain an essentially constant doping-mobility product value during deposition and can be regulated to obtain pre-selected base-emitter voltages at junctions within a resulting transistor.

Description

1288479 发明, DESCRIPTION OF THE INVENTION: TECHNICAL FIELD OF THE INVENTION The present invention relates to transistors, and more particularly to bipolar transistors having a graded base layer. [Prior Art] A bipolar junction transistor (BJT) and a heterojunction bipolar transistor (HBT) integrated circuit (1C) have been developed into important technologies for various applications, especially It is a power amplifier for high-speed circuits (greater than 10 billion bits per second) for wireless handsets, microwave instruments, and fiber-optic communication systems. Future demand is expected to require components with lower operating voltage, higher frequency performance, higher added power efficiency, and lower manufacturing cost. The turn-on voltage (Vbe〇n)# of the BJT or HBT is defined as the base-emitter voltage (Vbe) required to achieve a certain fixed collector current density (jc). For low power applications where the supply voltage is limited by the power requirements of battery technology and other components, this turn-on voltage can limit the usability of the component 0, unlike the emitter, base, and collector of BJT, which is made of a semiconductor material. Made, the HBT system is made of two dissimilar semiconductor materials. The band gap of the emitter semiconductor material should be _, the P of the semiconductor material to be the base is compared to the collector of the collector. The injection efficiency is excellent from the base-subjection from the base back to the emitter, and the 1288479 base with a small energy gap can reduce the turn-on power because of the carrier from the base to the collector. An increase in the injection rate will increase the current of the collector at a given base-emitter (four). However, the ability of the HBT semiconductor material to be aligned at the heterojunction and has a sudden discontinuity' can result in a spike in the conduction band at the emitter-base interface of the bladder. The effect of this conduction band is that the electrons are transmitted from the base to the collector. Because &, the electron stays at the base for a long time' leads to an increase in the degree of recombination and a collector current gain (reduction of the heart. As discussed above, since the open junction bipolar transistor is turned on, it is defined as The base-emitter voltage required to fix the collector current density' therefore reduces the collector current gain and effectively increases the resistance to open the circuit. Therefore, the manufacture of HBT semiconductor materials needs to be further improved to reduce the turn-on voltage, thereby improving the low Voltage-operated component. SUMMARY OF THE INVENTION The present invention provides an HBT having a collector of n-type dopants, a base formed on a collector and composed of a ΠΙ-ν family material (including a face and nitrogen), and a formation The n-type doped emitter on the base. The m_v material of the base layer has a carbon doping concentration of about χΠ)%-3 to about 7〇xl〇19cra_3. In a preferred embodiment, the base layer comprises gallium, indium, minced and nitrogen elements. The presence of indium and nitrogen reduces the band gap of the material relative to the band gap of GaAs. In addition, the dopant concentration in this material is high and the sheet resistance (Rsb) is low. These factors result in a lower open electrical dust relative to the 'base layer with similar doping concentration'. 1288479 In a preferred embodiment, the T 11 J-V compound material system can be represented by the chemical formula Gahlrix As. It is known that when a small amount of nitrogen is incorporated into Gai_xInxAs, the band gap of this material will substantially fall. Furthermore, because nitrogen deduces the 曰 U ^ push crystallization constant in the opposite direction to the steel, the appropriate ratio of indium to nitrogen is added to the material to grow the lattice matching force.

Gai_xInxAs A alloy. Therefore, it is possible to eliminate excess strain that causes an increase in the energy gap and a mismatch in the material. Therefore, the splicing / U ^ is chosen to reduce or eliminate the strain of indium to nitrogen ratio. In the roughening of the present invention and the identification of the J-level, the base layer of the ίίΒΤ

x=3y in GabxIrixASi-yNy. In a conventional HBT with GaAs, as the temperature increases, the emitter is injected to a higher degree, the recombination current of the inter-charge layer is higher, and the diffusion length in the base may be shorter, so the current gain is typical. It will be lowered. In the HBT towel with the GalnAsN base layer, as the temperature increases, a significant increase in current gain is found (about 3% increase per rc). This result is explained by the fact that the diffusion length increases with increasing temperature. If the electrons at the bottom of the band are limited to the state in which they are at least partially localized; Ping is expected to have such an effect, and as the temperature increases, they are thermally excited from the above state to other states in which electrons can more easily diffuse. . Therefore, designing the base layer with GalnAsN improves the temperature characteristics of the HBT of the present invention and reduces the need for a temperature compensated sub-circuit. $ HBT with a GalnAsN base layer has improved the common emitter output characteristics relative to conventional germanium with a GaAs base layer. For example, the offset (0ff set) voltage and the knee voltage of the HBT with the GalnAsN base layer are lower than the conventional HBT with the GaAs base layer. 1288479 In a specific aspect, the transistor is double A hetero heterojunction bipolar transistor (DHBT) whose semiconductor material is composed of a semiconductor material different from that of an emitter and a collector. In a preferred embodiment of the DHBT, the GalnAsN base layer can be represented by the chemical formula Ga^xIrixAs yNy, the collector is GaAs, and the emitter is selected from InGaP, AlInGaP, and AlGaAs. Another preferred embodiment of the invention is directed to HBT or DHBT, wherein the height of the conduction band peak is reduced while the energy band gap (Egb) of the base layer is reduced. The conduction band peak is caused by a discontinuity in the conduction band at the base/emitter heterojunction or the base/collector heterojunction. By reducing the lattice strain by matching the lattice of the base layer to the emitter and/or collector layers, the conduction band peaks are reduced. This is typically done by controlling the concentration of nitrogen and helium in the base layer. The base layer preferably has the chemical formula Ga^ xInxAsWNy, where X is approximately equal to 3y. In the specific grievances, the base can be graded in composition to produce a crevice gap layer with a relatively large knife-level gap at the emitter and a larger gap at the emitter. The energy band gap of the base layer is preferably about 20 meV to about 12 〇 meV lower than the surface of the base layer in contact with the collector. The energy band gap of the base layer is more linearly changed from the collector to the emitter across the base layer. The addition of nitrogen and indium to the GaAs semiconductor material reduces the band gap of the material... Therefore, the band gap of the Gai-xlrixASi-yNy semiconductor material is lower than that of GaAs. In the Gab»p-type base layer of the composition of the present invention, the energy band gap of the base layer is reduced at the collector by 1288479, compared to the energy of the GaAs over the base layer. In terms of the gap, the above-mentioned energy π gap is typically reduced by an average of about 10 〇 meV to about. In a physical aspect, the above-mentioned monthly b π gap is typically reduced by about 8 〇mey to about on average compared to the energy band gap of GaAs across the base layer. In another embodiment, the band gap is typically reduced by an average of about 1 〇meV to about 2 〇〇meV compared to the energy band gap of the GaAs across the base layer. This reduced band gap results in an open voltage (vbe, Qn) of the HBT having a graded Gai·» base layer that is lower than that of the HBT having a GaAs base layer, because Vbe, 〇n The main determinant is the inherent carrier concentration in the base. The intrinsic carrier concentration (ni) is calculated by the following formula: ni = NcNvexp (-Eg / kT) In the above formula, Nc is the effective density of the conduction band state; Nv is the effective density of the covalent band state; Eg is Can have a gap; τ is the temperature; and k is the number of the troughs. It can be seen from the equation that the inherent carrier concentration in the base is largely controlled by the band gap of the material used in the base. The energy band gap of the base layer is graded from the larger band gap of the base-emitter interface to the smaller band gap of the base-collector interface, which introduces a quasi-electric field that accelerates the electrons over the npn double The base layer in the polar crystal. The electric field increases the electron velocity in the base and reduces the collector transmission time, which improves RF (radio frequency) performance and increases the collector current gain (also known as dc current gain). In the case of HBTs with heavily doped collector layers, the dc gain (calling) is limited by the overall recombination in the neutral base (η = ι). The dc current gain can be estimated by the formula: /5 dc « ^ r /Wb (l) 1288479 In equation (1), p is the average velocity of the secondary carrier in the base ^ is the secondary load in the base The life of the child, and ' is the thickness of the base. The proper classification of the base layer in the HBT having the GaInAsN base layer compared to the unfractionated GalnAsN base layer results in a significant increase in 5 dc due to an increase in electron velocity. In order to achieve an energy band gap that is graded over the thickness of the base layer, the base layer is prepared such that the concentration of indium and/or nitrogen at the first surface of the base layer (by the near collector) is greater than at the base The second surface of the layer (near the emitter) is high. The change in the content of indium and/or nitrogen is preferably a band gap which changes linearly across the base layer to cause linear grading. The concentration of the dopant (e.g., carbon) is preferably maintained constant throughout the base layer. In a particular aspect, the 'xInxASl_yNy base layer (e.g., the base layer of the DHBT) is graded such that at the collector X and 37 are approximately equal to 〇. 而 and at the emitter are graded and the sum is approximately equal to zero. In another embodiment, the GaixIMsiA base layer is demarcated from a surface in contact with the collector at the base layer to a range of from about 0.2 to about 〇·(10), and is graded to be in contact with the emitter at the base layer. The χ value at the surface is in the range of Ο" to zero, provided that the X value at the surface where the base layer is in contact with the collector is larger than at the surface where the base layer is in contact with the emitter. In this particular aspect, y may remain fixed throughout the base layer or may be linearly graded. When y is linearly graded, the base layer has a y value ranging from about 0.2 to about 0 02 at the surface where the base layer is in contact with the collector, and is graded such that the y value at the surface where the gate layer is in contact with the emitter is A range of approximately Q1 to zero, provided that the y value at the surface where the base layer is in contact with the collector is greater than the surface at which the pole layer is in contact with the emitter. In a preferred embodiment 2, 1288479 X is approximately 0.06 at the collector and is linearly graded to approximately 〇 01 at the emitter. In a preferred embodiment, X is approximately 〇·〇6 at the collector, and is linearly graded to approximately 〇·〇1 at the emitter, while y is approximately 0.001 in the entire base layer. . In another embodiment, the invention is a method of forming a graded semiconductor layer having a substantially linearly graded energy band gap from the first surface through the layer to the second surface and substantially fixed The product of the doping X mobility. The method includes (a) comparing the product of doping and mobility of a plurality of correction layers, wherein each layer is among the organometallic compounds of the 沉积 or v group atoms of the deposition period or the w _ carbon compounds of the deposited carbon. The shape of the lighter is determined by the flow rate of the lighter, so as to form a substantially constant pusher χ move! The relative flow rate of the organometallic compound and the quaternary carbon; And (8) flowing the organometallic compound and the tetra-functionalized carbon compound on a surface at the relative flow rate to form a product of substantially constant doping X mobility, and during the grading period The semiconductor two == flow rate ' thereby forming a substantially linearly graded energy band gap in the crucible. The base layer can also classify the dopants such that the dopant concentration near the drain is relatively 胄, έ && The thickness is gradually reduced to the base species so that the material can be banded (four) to be in the f package or multiple transition layers. It is possible to use a low energy band gap; (8) layer, graded energy band (four) layer, doped peaks or a combination thereof to pass the 12 1288479 layer to minimize the conduction band peak. Additionally, - or a plurality of lattice matching layers may be present between the base and the emitter or between the base and the collector to reduce the lattice strain of the material at the heterojunction. The invention also provides a method of making bribes and bribes. The method includes growing a base layer composed of gallium, indium, and argon on the n-type doped shirt. The base layer can be grown using internal and/or external carbon sources to provide a carbon doped base layer. An n-type doped emitter layer is then grown on the base layer. The use of internal and external carbon sources to provide carbon dopants for the base layer can help to form materials with relatively high carbon dopant concentrations. Typically, a degree of dopant of from about i5 xi 〇 iw to about 7. 〇 1 ◦ cm is achieved using the method of the present invention. In a preferred embodiment, the degree of alteration of about 3.QxlG1Wi|jM 7 Qxi〇i9cm_3 can be achieved by the method of the present invention. The material concentration of the material is reduced by the concentration of the dopant in the material, which reduces the sheet resistance and band gap of the material. Therefore, the higher the concentration of the tamper in the base layer of HBT and bribe, the lower the opening voltage of the component. The present invention also provides a material represented by the chemical formulas $ Γ γ . χτ, 里田化予式 GahInxAs yNy, wherein "the mouth y is independently from about h 〇χΐ〇 _4 to about 2. 〇Χΐ (Γΐ °Χ is preferably about equal to x and 3y, more preferably about 0.01. In a specific aspect, the material is doped with carbon of about 15 〇 〇 i9 cm _ 3 to about 7. 〇 x 1 〇 1 W Han. In a particular embodiment, the concentration of carbon dopant is about 3. 〇 x1 () 1 W to about 7 Gxi Qlw. Lowering the turn-on voltage allows for better management of the voltage budget of GaAs-based wired and wireless rf circuits, such The circuit is subject to a standard fixed voltage supply or is subject to battery output. Lowering the turn-on voltage can also change the relative magnitude of the various base current components in a GaAs-based HBT. It has been shown to be both junction temperature and applied stress. The DC current gain stability of the function is heavily dependent on the relative magnitude of the base current component. The reduction of the reverse hole injection caused by the low open voltage is beneficial to the temperature stability and long-term reliability of the component. Therefore, the relatively unstrained Ga^Jr^Asi-yNy base material with high dopant concentration can significantly improve the RF performance of GaAs-based HBT and DHBT. [Embodiment] The preferred embodiment of the present invention from the bottom The above and other objects, features and advantages of the present invention will become more apparent from the aspects of the appended claims. The same parts in the drawings. The drawings are not necessarily to scale, but rather to demonstrate the principles of the invention. The steroidal material is a lattice comprising at least one element selected from the group (4)(1)(1) and at least one essay; Week s table V (A) block element of semiconductor

. In a specific aspect, the Ιπ-V material H is selected from a crystal lattice including gallium, indium, antimony and nitrogen. 111-V family in Guzu County

Armored materials can best be represented by the chemical formula G yNy, where Yihe y individual 猸 ☆ from 4 nlnxASl_ , y individually independently about 1. 〇 >< 1 (^ to about 2. 〇 xl 〇 _hX more The better is about the big, the spoon ^ ^ 0. In a best specific bear sample, X and is about 〇.. ~ "Transitional layer" used in the "transitional layer" Refers to the layer between the base/emitter heterojunction and has the 14 1288479 function of minimizing the conduction band peaks of the different meta-bonds. The smallest method is to use a series of transition layers in which the band gap of the transition layer is gradually reduced from the transition layer closest to the collector to the transition layer closest to the base in the heterojunction of the base/collector. Ground, in the heterojunction of the emitter/base, the energy band gap of the transition layer is gradually reduced from the transition layer closest to the emitter to the transition layer closest to the base. Another way to minimize the conduction band peak Is to use a transition layer with a graded energy band gap. The energy gap of the transition layer can be By stratifying the layer dopant concentration, for example, the dopant concentration of the transition layer can be higher near the base and gradually decrease near the collector or emitter. It is optional to use lattice strain to provide a graded energy gap with a transition layer. For example, the transition layer can be graded to have a minimum lattice strain on the surface of the contact base. Increasing the lattice strain of the surface contacting the collector or emitter. Another way to minimize the conduction band outburst is to use a transition layer with a peak of dopant concentration to minimize the conduction band peak. One or more methods can be used in the present invention. The transition layer of the HBT suitable for the present invention includes a shirt, InGaAs, and InGaAs N. The lattice matching layer is a layer that grows on a material having a different lattice constant. Typically, the thickness is about 500 A or less, and is consistent with the lattice constant of the underlying layer. If the lattice matching material has no shoulder change, this results in an energy band gap between the underlying layer and the energy of the lattice matching material. The band gap between the gaps. The method of forming the lattice matching layer is familiar to this: It is known to the artist, and can be seen in the third of the "Gailium Arsenide Techn〇iogy" by 9 Ferry et al. 〇 3 to 328 (in 1985 15 1288479, published by Howard W. Sams, Inc., Indianapolis, Indiana), which is hereby incorporated by reference. A material example of a wafer matching layer suitable for the present invention is InGaP. HBT and DHBT of the base layer of the depressing composition The HBT and DHBT of the present invention can be prepared using an appropriate epitaxial growth system of metal organic chemical vapor deposition (MOCVD). Suitable examples of M〇CVD epitaxial growth systems are the AIXTR0N 2400 and AIXTR0N 2600 platforms. In the HBT and DHBT prepared by the method of the present invention, an undoped GaAs buffer layer can be grown typically after removing the adsorbed oxide on the spot. For example, a sub-collector layer comprising a high concentration of n-type dopant (e.g., a dopant concentration of about lxl 〇 18 cm 3 to about 9 < 1018 ciir 3 ) can be grown at a temperature of about 7 ° C. A collector layer having a low concentration of n-type dopant (e.g., a dopant concentration of about 5 x 1 〇 15 cnr3 to about 5 x 16 〇 16 cm -3 ) can be grown on the sub-collector layer at a temperature of about 7 〇〇 ° C. The secondary collector and collector are preferably GaAs. The secondary collector layer typically has a thickness of from about 4 A to about 6000 A, while the collector layer typically has a thickness of from about 3000 A to about 5000 A. In a particular aspect, the dopant in the secondary collector and/or collector is germanium. The lattice matched I nGaP tunneling layer can be selectively grown on the collector under typical growth conditions as needed. The lattice matching layer typically has a thickness of about 500 A or less, preferably about 200 A or less, and a dopant concentration of about 1 X1 〇 16 cn T3 to about 1 X 1 〇 18 ciir 3 . One or more transition layers may optionally be grown on the lattice matching layer or on the collector under typical growth conditions as desired (if no lattice 1288479 layer is used). The transition layer may be prepared from n-doped GaAs, „type doped InGaAs or n-type doped InGaAsN. The transition layer may be selectively graded on the composition or dopant as needed, or may comprise ^ The peak of the dopant. The transition layer typically has a thickness of about 75a to about 25A. If a lattice matching layer or a transition layer is not used, the InGaAsN base layer of the carbon-doped carbon is grown on the collector. The base layer is low. It grows at a temperature of about 75 (TC) and is typically about 400 A to about 1500 A thick. In a preferred embodiment, the base layer is grown at a temperature of from about 500 ° C to about 600 ° C. The carbon-based InGaAsN base layer can optionally be grown on the transition layer or on the lattice matching layer (if no transition layer is used). The base layer can be made using a suitable gallium source (eg trimethylgallium or tris) Ethyl gallium), arsenic source (such as bismuth, tributyl hydrazine or trimethyl hydrazine), indium source (such as trimethyl indium) and nitrogen source (such as ammonia or dimethyl hydrazine) to grow. Preference is given to arsenic. Low molar ratio of source to gallium source. Typical The molar ratio of arsenic source to gallium source is less than about 3.5. The ratio is preferably about 2·〇 to about 3·〇. Adjusting the degree of nitrogen and steel source to obtain about 〇〇1% to about 2% by weight of indium and about 0.01% to about 20% of nitrogen. In a preferred embodiment, the indium content of the base layer is about three times the nitrogen content. In a better specific aspect The indium content is about 1%, and the nitrogen content is about 〇3%. In the present invention, an InGaAsN layer having a high carbon dopant of about 1.5×10 〇19 cm_3 to about Å can be used externally. A source of carbon or an organic metal source (especially a source of gallium) is available. A suitable example of an external carbon source is carbon tetrabromide. Carbon tetrachloride is also an effective source of external carbon. 17 1288479 Between the base and the emitter Need to be selectively doped by n-type

GaAs, n-type doped InGaAs or n-type doped InGaAsN grow one or more transition layers. The transition layer between the base and the emitter is doped lightly (e.g., about 5·〇χ1015 (μιγ3 to about 5.〇xl〇i6cnr3), and may optionally include a peak of the dopant. The transition layer is preferably from about 25 A to about 75 A. The emitter layer is grown on the base at a temperature of about 700 ° C or can optionally grow on the transition layer as desired, and is typically about

400A to about 1500A thick. The emitter layer includes, for example, inGaP, AiinGaP, or AlGaAs. In a preferred embodiment, the emitter layer comprises inGap. The emitter layer may be doped n-type to a concentration of about 1. 〇xl 〇 17 cm -3 to about 9. 〇 xl 〇 17 ciir 3 . An emitter contact layer of GaAs comprising a high concentration of n-type dopant (e.g., about l. 〇xl018ciir3 to about 9><1018αιΓ3) can be selectively grown on the emitter at a temperature of about 700 ° C as needed. . Typically, the emitter contact layer is from about 1 000 A to about 2 A thick. An InGaAs layer having a progressive indium composition and a high concentration of n-type dopant (e.g., about 5xl018cin3 to about 5<1019cnr3) is grown on the emitter contact layer. This layer is typically about 400A to about ιοοο thick. Example 1 To demonstrate the effect of reducing the band gap of the base layer and/or minimizing the conduction band peaks at the emitter/base junction, three different GaAs-based bipolar transistor structures were compared: BJT of GaAs emitter/GaAs base, HBT of InGaP/GaAs, and DHBT of inGap / GalnAsN of the present invention. The general representative structure of inGaP/GaInAsN DHB butyl 18 1288479 for the bottom experiment is illustrated in Figure 1. Since both the base and the collector are formed of GaAs, there is only one heterojunction at the emitter/base interface. The band gap of the GaAs base layer of InGaP/GaAs HBT is better than that of In (Jap/ GalnAsN DHBT base layer. Since the emitter, collector and base of bjt are made of GaAs, there is no Heterojunction. So use the GaAs BIT structure as a reference to determine the impact of the conduction band peak at the base/emitter interface on the collector current characteristics of InGaP/GaAs Ηβτ, if any. In the middle, the InGaP is chosen as the emitter, and the base is extremely Gai_xlMsi_A, because the band gap of Μ# is very wide, and its conduction band is aligned with Gai xlMsi—the conduction band with the base. The comparison of InGaP / GaInAsN and InGap / (10) HBT is used to determine the effect of the base layer with a lower band gap on the collector current density. The GaAs elements used in the discussion below all have a doping inverse grown by M0CVD. The base layer, wherein the dopant concentration varies from about 1 · $X1 〇i to about 6.5xl 〇i9cnr3, and the thickness varies from about 5 〇〇A to about 15 ,, so that the base sheet resistance 〇 ^) Between 100Ω/□ and 4〇〇Ω/□. Large area components (L = 75 #m >< 75 ν m) were fabricated using a simple wet etch and tested in a common base architecture. A relatively small amount of indium (X~1%) and nitrogen (y~〇·3%) were added in portions to form two different sets of InGaP / GaInAsN DHBT. The growth of each group has been optimized to maintain a high and uniform carbon dopant level (>2.5xl〇i9cnr), good mobility (~85 cm2/v-s), and high dc current gain. (Rsb~300 Ω /□ is >6〇).

A typical Gummel plot of GaAs / GaAs BJT, InGaP 1288479 / GaAs HBT, and InGaP / GalnAsN DHBT with comparable base sheet resistance is plotted and overlapped in Figure 2. The collector currents of InGaP / GaAs HBT and GaAs / GaAs BJT are indistinguishable by more than five orders of magnitude (five 〇) in excess of current until the difference in effective series resistance affects the current-voltage characteristic. On the other hand, the collector current of InGaP / GalnAsN DHBT is twice that of GaAs / GaAs BJT and InGaP / GaAs HBT over a wide bias range, which corresponds to a collector current density of 1 · 78 A/cm 2 (Jc The opening voltage under ) is reduced by 25· OmV. The observed increase in the low bias base current (n = 2 component) in BJT is consistent with the increase in space charge recombination driven by the band gap. The neutral base recombination component of the collector current in InGaP / GalnAsN DHBT is driven higher than the InGaP / GaAs HBT due to an increase in collector current and a decrease in secondary carrier lifetime or carrier velocity. (Inbr=Icwb/^r) has increased. In the inGaP / GalnAsN DHBT device prepared so far, the element with a base sheet resistance of 234 Ω /□ has reached a peak dc current gain of 68, which corresponds to a 11.5 mV reduction in the turn-on voltage and a base sheet resistance of 303 Ω. The /□ component has reached a peak dc current gain of 66, which corresponds to a 25 〇mV reduction in the turn-on voltage. For these structures, this represents the ratio of the highest known gain to the base sheet resistance (/3/Rsb~0.2 to 0.3). The reduction of the energy band gap of the Gai_xInxAs yNy base is the cause of the observed decrease in the turn-on voltage, such as low temperature (77. 1 〇 luminescence is demonstrated. 0 [Sense 1 ^ measurement shows that the crystal layer mismatch of the base layer is the smallest (<250arcsec). In the popularization limit, the ideal collector current density of a bipolar transistor with a base-emitter voltage (Vbj as a function) can be approximated as: 20 1288479

Jc=(qDnn2ib/pbWb)eXp(qvbe/kT) where

Base push and width; diffusion coefficient ib The inherent carrier concentration in the base represents nib as a function of the base layer energy band gap (Egb), and the base plate resistance (Rsb) is used to rewrite the base push and The width of the multiplication, the open voltage can be expressed as a logarithmic function of the base sheet resistance.

Vbe-A ln(Rsb)+V〇(3) and A=(kT/q) (4) and V〇=Egb/q-(kT/qHMqZem/jc) (5) where 1 and Nv are conduction bands and The effective density of the state of the valence band is 'and # is the main carrier mobility in the base layer. Figure 3 plots multiple in (jap/ GaAs ΗΒΤ, GaAs/GaAs BJT and InGaP/GalnAsN DHBT opening voltages as a function of base sheet resistance for Κ·78 A/cm2. InGaP / GaAs HBT and GaAs / GaAs BJT Without any conduction band peaks, the turn-on voltage is qualitatively present with the same logarithmic dependence as the equation (2) for the base sheet resistance. Quantitatively, the base-emitter voltage (ybe) The change in the base sheet resistance is not as dramatic as represented by equation (3) (A = 〇 · 〇 174 mV, not 〇 · 0252 mV). However, the observed decrease in A is compared to the thin base GaAs bipolar element. The quasi-ballistic (quasiballistic) transmission is consistent. The conclusion drawn from the comparison of the characteristics of GaAs / GaAs BJT is that the effective height of the conduction band peak of InGaP / GaAs HBT can be zero, 21 1288479 and the collector current is ideal. The behavior of (Π=1). Therefore, InGaP / GaAs HBT can be designed to have substantially no conduction band peaks. Previous studies on AlGaAs/GaAs HBT have found similar results. To further reduce these components in the fixed Base The turn-on voltage under the resistor requires the use of a base material with a lower band gap while still maintaining the continuity of the conduction band. Gab xInxAs yNy can be used to reduce Egb while maintaining near lattice matching. As can be seen, the turn-on voltage of the two inGaP / GalnAsN DHBTs follows the logarithmic dependence of the resistance of the base sheet, which shows that the conduction band peak is approximately zero. Furthermore, compared to the observed InGap / GaAs HBT and GaAs / GaAs In the case of BJT, the turn-on voltage of one of the groups is shifted downward by 11.5 mV and the other group is shifted downward by 25. 〇mV (two dashed lines). The above experiment shows that the opening voltage of the GaAs-based HBT can use the InGaP/GalnAsN DHBT structure. And falling below the turn-on voltage of the GaAs BJT. The low turn-on voltage is achieved through two key steps. By selecting the base and emitter semiconductor materials (the conduction band is about the same energy P white), First, the base-emitter interface is optimized to suppress the large peak of the conduction band. This is successfully done using InGaP or AlGaAs as the emitter material and Gaj\s as the base material. The band gap of the base layer further reduces the turn-on voltage. This is achieved by adding both indium and nitrogen to the base layer while still maintaining the lattice matching of the entire Ηβτ structure. It can be done with appropriate growth parameters. To increase the collector current density by a factor of two without significantly sacrificing the lifetime of the base doping or secondary carrier (Rsb = 234 Ω / port / 5 = 68). These results show that the use of GaixIiMSbNy material provides a way to reduce the turn-on power based on GaAs #HBT and DHBT. Since 22 1288479 incorporates indium and nitrogen in GaAs to reduce the band gap of the material, a larger percentage of indium and nitrogen are added to the base. If high p-type doping concentration is maintained, GaAs-based HBT and DHBT can be expected. The opening voltage is greatly reduced.

The decrease in the energy band gap of the GalnAsN base is assumed to be the cause of the observed decrease in the turn-on voltage, which has been confirmed by low temperature (77. 趵 luminescence. Figure 4 compares the luminescence spectra of InGaP/GalnAsN DHBT and conventional InGaP/GaAs 。. The base layer signal of the InGaP/GaAs HBT is lower than the collector (1.455eV vs. 1.507eV) due to the band gap narrowing effect caused by the high doping level. From InGaP / The base layer signal of GaInAsN DHBT has been reduced by 丨·4〇8eV, which is caused by the band gap narrowing effect and the reduction of the base layer band gap caused by the addition of indium and nitrogen in the base layer. In this comparison, the degree of doping is comparable, and compared to the band gap of the GaAs base, the proposed base layer signal position has a 47 meV reduction which can be equivalent to the base layer band gap of the GaInAsN base. Decrease. The displacement of this illuminating signal is well correlated with the measured opening voltage drop of 45mv. In the absence of a conduction band peak, the reduction of the opening voltage can be directly related to the reduction of the band gap of the base layer. DCXRD The spectrum demonstrates the effect of adding carbon dopants and indium to GaAs semiconductors. Figure 5 shows DCXRD spectra from both InGaP / GaInAsN DHBT and standard InGaP/GaAs HBTs of comparable base thickness. In InGaP / GaAs HBT, base The layer can be seen as the shoulder on the right hand side of the GaAs substrate spike, approximately corresponding to the position of +90 arcsec, due to the tensile strain produced by the high concentration carbon dopant of 4x1019cnr3. In particular, the base layer peak of the InGaP / GalnAsN DHBT junction 23 1288479 is at -425 arcsec. In general, the peak position associated with the base of the GalnAsN is a function of the concentration of indium, nitrogen and carbon. Adding indium to GaAs increases The compact strain 'and both carbon and nitrogen are compensated by tensile strain. Maintaining a high p-type doping level when indium (and nitrogen) is added to the carbon doped GaAs requires careful growth optimization. A rough estimate of the degree of doping of the action can be obtained from a combination of measured base sheet resistance and base thickness values. Base doping can also be obtained by first selectively etching to the top of the base layer'. Polaron The CV profile is confirmed. Figure 6 compares the p〇iaron c-v doping profile of the GaAs base layer and the GalnAsN base layer. In both cases, the doping level exceeds 3xl〇i9cm_3. Another alternative DHBT structure is shown having a fixed composition of Gal nAsN base layers that employ a transition layer between the emitter/base and collector/base junctions. In addition, a lattice-matched I nGaP tunneling layer is employed between the transition layer and the collector.

The DHBT of the base layer of the UligL component has all the layers of the DHBT constituting the graded base layer, which can be grown in a manner similar to the DHBT of the base layer having a fixed composition, with the exception of bonding from one of the transistors to the base. The pole layer is joined to the other as a base layer with a graded energy gap. For example, if a germanium matching layer or transition layer is not used, the GaInAsN base layer doped with carbon and capable of band gap classification may grow on the collector. The carbon-doped and graded Gal nAsN base layer can optionally be grown on the transition layer or on the lattice matching layer if desired (if no transition layer is used). The base layer can be grown at temperatures below about 750 〇c and is typically 24 1288479 and typically about 400A to about 1500A thick. In one embodiment, the base layer is grown at a temperature of from about 500 ° C to about 600 ° C. The base layer may be of a suitable gallium source (eg, trimethylgallium or triethylgallium), a Shishen source (eg, lanthanum, tris(tertiary butyl) ruthenium or tridecyl ruthenium), an indium source (eg, triterpenoid) Base indium) and nitrogen sources (such as ammonia, dimethyl hydrazine or tertiary butylamine) to grow. Preference is given to using a low molar ratio of arsenic source to gallium source. Typically, the ratio of the source of the Shishen source to the gallium source is less than about 3.5. The ratio is preferably from about 2 · 0 to about 3 · 0. The extent of the nitrogen and indium sources can be adjusted to obtain a material in which the Group 111 element is from about 1% to about 2% indium and the v-factor element is from about 0.01 to about 20% of nitrogen. In a particular embodiment, the content of 'Group III element indium varies from about 1% to 20% at the base/collector junction to about 〇% to 5% at the base/emitter junction, and The nitrogen content of the v group element is substantially fixed at about 〇·3%. In another embodiment, the indium content of the base layer is about three times the nitrogen content. As discussed previously with a fixed composition of InGaAsN base layer, it is believed that an InGaAsN layer having a high carbon dopant concentration of about 1.5×1 〇i9cnr3 to about 7.5×10i9cnr3 can reuse an external carbon source in addition to the gallium source (eg, Tetrahalide carbon) is obtained. The external carbon source used may for example be carbon tetrabromide. Carbon tetrachloride is also an effective source of external carbon. The amount of carbon dopant contributed to the InGaAsN base layer by the organic indium compound used as the indium source gas is different from the organogallium compound used as the gallium source gas, so during the growth of the base layer The flow rate of the carbon dopant source gas is adjusted so as to maintain a constant carbon doping concentration in the graded InGaAsN base layer. 25 1288479 In a specific evil sample, the carbon on the graded base layer is formed. The change in flow rate of the source gas is determined using the method described below. / or the order of the magneto-trimethyl hydrazine source of the graded conductor layer. At least two sets of calibration HBTs are prepared, each of which contains at least two members (a bribe can be used instead of HBT). The thickness of the base layer for all calibrations is ideally the same, but this is not a requirement, and each HBT has a fixed composition, such as a fixed composition #(10) pair or an InGaAs base layer and in both layers. A constant carbon dopant concentration. Each group is formed at a source gas flow rate different from that of another group (for example, a group of indium or a group of nitrogen for group V), such that members of each group have gallium different from members of other groups. Indium, arsenic and nitrogen. For example, indium is used as an additive that affects the band gap classification. Each member of a particular group grows at a different external carbon source (e.g., four evolutionary carbon or carbon tetrachloride) flow rate, so each member of a particular group has a different degree of carbon inclusions. The product of the doping X mobility of each member is determined and the flow rate of the carbon source is plotted. The product of the doping X mobility of the members of each group varies in proportion to the carbon source gas flow rate. The flow rate of the product of the doping X mobility of the five groups of bismuth to the carbonized carbon is shown in Fig. 8. Alternatively, each set of calibration biliary or may be formed by holding a stone source gas (eg, four desertified carbon) that determines the maneuver rate, and individual samples in each group may be relative to the other The flow rate of the source gas is formed by the flow rate of the (four) m or ν group additive. 26 1288479 Obtaining a fixed doping X mobility ♦ The flow rate of the source gas is derived from the gas source in the accumulation The stroke-strip is obtained by traversing Figure 8 (e.g., the line of the doping x mobility product of 4 = ', such as the bar + the line on the x-axis). The place where the line is crossed with each group (4) The body flow rate is obtained when the nutrient, / the steel source gas of the group "the external carbon required for the product value of the I heterogeneous mobility is Qiu,". For the product value of the fixed doping X mobility, the external anaesthetic source flow rate _ source gas flow rate is shown in Figure 9. Different Lift: The product of moving J·sheng can draw similar lines in the same way. The collector current of each ΗΒΤ is plotted as the base-emitter number' and the resulting curve is the same as having the (10) base layer and the others (the same as the group of = = ΗΒΤ (for example with the same dopant) The graphs of the concentration, the same = base, emitter and collector layer thickness, etc. are compared. The voltage difference between the curves at the characteristic collector current is the change of the base-emitter voltage be (△ Vbe), which is attributed to the lower band gap of the base layer caused by the addition of germanium and nitrogen during the formation of the base layer. Figure 1 shows the JJBT with the base layer of GalnAsN and the base of GaAs. The collector of the layer HBT "L 乂Vbe is a graph of the function. The horizontal arrow drawn between the two curves is Δ Vbe. The Δ vbe of each member of all groups is determined, and the carbon source gas flow rate is determined. Plot. The Δvbe versus carbon tetrabromide flow rate for each member of the five groups of HBTs used in Figure 8 is plotted in Figure π. Note that the ΔVbe of a group of members spans a range of ΔVbe for this set, this range You can find the most suitable straight line. These lines are used to decide (interpolate) Allows the use of a specific group of indium source gas flow rates but the carbon source gas flow rate is different from that of the other members of the group. Δ Vbe. 27 1288479, for the product of the solid doping x mobility, Δ vbe is indium: the original gas flow rate is linearly varied, as can be seen when the interpolated ΔVbe of the fixed doping mobility product is plotted as a function of the indium source gas flow rate. Figure 12 shows that the pattern used for the five groups of Figure 11 is used to determine the source of indium required at the base/emitter and base/set (4): to the desired AVbe. Gas flow rate: Once the flow rate of the indium source gas is determined, use Figure g to determine the carbon source gas flow rate required at this = source gas flow rate to obtain the desired dopant X mobility. According to the same procedure, the indium source gas flow rate and the carbon source milk flow rate required at the base/collector junction are determined to maintain the desired composition in the layer (10). Fixed dopant X shift Productivity. When the base layer grows from the base/collector junction to the base/emitter junction, the indium source gas flow rate and the carbon source gas flow rate vary linearly with respect to the extent of gallium and arsenic to these junctions. The values determined by these source gases are used to obtain a linear graded base layer having the desired band gap level. Example 2 The GaAs elements used in the discussion below all have a carbon-doped base grown by M〇CVD. a layer in which the dopant concentration varies from about 3〇xl〇19cnr3 to about 5.〇xl〇i9cm_3, and the thickness varies from about 5〇〇A to about 15〇〇, so that the base sheet resistance (Rsb) is at 100Q /□ to 65〇ω/□. Large area components (L = 75 // mx 75 // m) were fabricated using a simple wet etch and tested in a common base architecture. A small amount of indium 28 1288479 (x~1% to 6%) and nitrogen (y~〇·3%) were added in portions to form two different sets of InGap / GalnAsN DHBT. The growth of each group has been optimized to maintain a high and uniform carbon dopant level (>2.5><1019cnr3), good mobility (~cmVV-s), and high dc current Gain (Rsb~300 Q/□ is >6〇). The DHBT structure having the GalnAsN base layer of the compositional composition for the bottom experiment is shown in Fig. 13. An alternative DHBT structure having a base layer of compositional composition is shown in Figures 7B and 7C. The DHBT structure of the GalnAsN base layer with a fixed composition for the bottom experiment is shown in Figure u for comparison. Figure 15 shows the DHBT of the fixed base with a comparable open voltage and base sheet resistance and the DHBT of the graded base. Gummel map. The neutral base component of the base current in the graded base structure is significantly lower, exhibiting a peak dc current gain that can be more than twice that of the fixed base structure. Figure 16 compares the dc current gain as a function of the base plate resistance for a fixed and graded DHBT structure with similar thickness variations. The increase in the ratio of the gain to the base sheet resistance is significant. Although the ratio of the gain of the DHBT to the resistance of the base sheet depends on the growth conditions used and the specific details of the overall structure, it has been observed that the DHBT with a graded base layer has a dc current gain that is better than a DHBT with a fixed base layer. - Increase by 50% to 1%. 9 Figures 17 and 18 compare the Gummel plot and gain curve for a graded base structure and two fixed base structures. The base composition of the first fixed base structure corresponds to the base layer of the graded base at the base/emitter junction. The base composition of the second fixed base structure corresponds to the base layer of the graded base at the base/collector junction. The turn-on voltage of the graded base structure is between the two 29 1288479 end structures, but is weighted towards the base/emitter end. The dc current gain of the graded base structure is 50% to 95% higher than the end structure, and most of this increase in dc current gain is due to an increase in electron velocity. On-wafer FF testing was performed on 70 pieces of 2-finger, 4/zmx4//m emitter area using the HP 8510C parametric analyzer. The open and shorted structures are used to remove the embedded mistletoe and the cutoff frequency (ft) of the current gain is extrapolated using a slope of -20 dB/10 of the small signal current gain (H21). Figure 19 combines the dependence of ft and collector current density (Jc) on the two structures. Figure 20 illustrates the relationship of small signal gain versus frequency at a particular bias point. As Jc increases and the base transition time (tj begins to play a limiting role throughout the transition time, although the base thickness of the graded base structure is large (the fixed base layer is 60 nm thick, and the graded base) The layer is 8〇nm thick), the ft of the graded base structure still becomes significantly larger than the structure of the fixed composition. The fixed peak of the 6〇nm fixed composition of the GalnAsN base is 53 GHz, and the peak of the 80nm composition is graded GalnAsN base. Ft is 6 〇 GHz. Therefore, the cutoff frequency of the current gain is increased by 13%. In order to compare the RF results of the DHBT with the fixed and graded GaInAsN base layer and the conventional GaAs HBT, the 匕 value of Figure 19 can be applied. This is a function of the zero-input current breakdown voltage of the transistor. This figure is compared with the peak or near-peak f* values of the traditional GaAs HBT quoted in the literature. It is expected that the ft value distribution of conventional GaAs HBTs is quite extensive because this data is compiled from use. Many groups of different stupid crystal structures, component sizes and test conditions, and only to give an overview of current industry standards. Βν^. Often must be estimated from the quoted collector thickness, assuming 301288479 = thickness shown in FIG. 2 1 a), BVeb. And the relationship between Βν "." also shows three simple calculations of the expected dependence of M(10) as shown in Fig. 2i, which assumes that the transition time of the space charge layer of Γ: = is earlier by the electron saturation τ velocity (vs) Purely associated with Xc. In the baseline calculation, as expected from the calculation of 1 000 A GaAs base > μ 丄, 9 M〇nte-Car! ,, τ b is false · 115 ps and the sum of the remaining emitter and collector transition times (le+lc) is considered to be 0·95 ps.

- Review view 21 shows that although the fixed composition of (10) (10) is not completely outside the expected range of the traditional GaAS-based, it is clearly at the lower end of the distribution. There is a significant improvement in the graded base structure. The first juice difference (:b is reduced to a 2/3 baseline) suggests that the base transition time is reduced by approximately (10) relative to the structure of the fixed composition. Compared to the base layer of the fixed composition, t, this shows that the carrier velocity doubles in the graded base layer, which is due to the increase in the carrier's thickness by two times (2x). % is expected to reduce the export rb to 1/2 χ 4/3 = 2/3.

The third calculation (rb reduced by 11/3 and (re+rc) reduced to 1/2 of the baseline) approximates the use of thin and/or graded base structures and has improved component layout and size (to enable rb, Case under re and rc minimum Example 3 In order to improve amplifier efficiency and thus reduce operating voltage and extend battery life, it is desirable to reduce the offset voltage (VCE sat) and the skew voltage (Vk). One way to reduce the offset voltage is to minimize the asymmetry of the base/emitter and base/collector diodes for the turn-on voltage. Although the collector band gap 31 1288479 is wide, the DHBT has been shown to produce a potential barrier that results in a higher Vk and lowers the efficiency of the heterojunction. Low VCE, sat value, but in fact, this is because it is difficult to control the base/set insertion of a thin layer (penetrating collector) with high energy band gap, allowing simultaneous reduction of vCE, sat and vk, and improved components s efficiency. Figure 22 shows an illustration of a DHBT having a graded GalnAsN base layer and a tunneling collector. The base layer is graded such that there is an energy difference of approximately 40 meV across the band gap between the emitter and collector junctions. A 1 〇〇 thick tunneling collector is formed between the base and the collector, which is composed of a high energy band gap material In〇 5Ga〇 5p. Figure 23 shows an illustration of the band gap of the DHBT of Figure 22. DHBT is fabricated using a simple wet etch process for large area components (L = 75 vm x 75 vm) and tested in a common base and common emitter architecture. Figure 24 shows its Gummel diagram, while Figure 25 shows the common emitter feature of the DHBT of Figure 22. As can be seen in Figure 24 and the carrier, the component has a low offset voltage of approximately 〇12ν. The present invention has been particularly shown and described with reference to the preferred embodiments of the present invention, and it will be understood by those skilled in the art Make a variety of changes in style and detail. BRIEF DESCRIPTION OF THE DRAWINGS (I) Schematic Part FIG. 1 illustrates a preferred embodiment of the InGaP / GalnAsN DHBT structure in which X is approximately equal to 3 y. 32 1288479 FIG. 2 is a Gu匪el diagram illustrating base and collector currents as a function of turn-on voltage for the InGaP/ GalnAsN DHBT of the present invention and prior art InGaP/GaAs HBT and GaAs/GaAs B JT . Figure 3 illustrates the opening of the InGaP/GalnAsN DHBT of the present invention and the prior art InGaP / GaAs HBT and GaAs / GaAs BJT as a function of the base sheet resistance (when Jc = 1.78 A/cm2) ). Figure 4 illustrates the luminescence spectra measured for both the InGaP/ GalnAsN DHBT of the present invention and the prior art InGaP/GaAs HBT at nominal base thicknesses of 1 000 A, 77 QK. Luminescence measurements were taken after etching away the InGaAs and GaAs cap layers and selectively terminating at the InGaP emitter tip. The energy band gap of the n-type GaAs collector of the InGaP/GaAs HBT and the InGaP/ GalnAsN DHBT is 1.507 eV. The energy band gap of the p-type GalnAsN base layer of the InGaP / GaAs HBT is 1. 455 eV, and the band gap of the p-type GalnAsN base layer of the InGaP / Galn AsN DHBT is 1. 408 eV. Figure 5 illustrates a double crystal X-ray diffraction (DCXRD) spectrum of both the InGaP/ GalnAsN DHBT of the present invention and the prior art InGaP / GaAs HBT at a nominal base thickness of 1500A. The position of the base layer peak is indicated. Figure 6 is a Polaron C-V profile illustrating the carrier concentration of the base layer thickness in the InGaP/GalnAsN DHBT of the present invention and the prior art InGaP/GaAs HBT. The nominal base thickness of InGaP / GalnAsN DHBT and InGaP / GaAs HBT is ΙΟΟΟΑ. The P〇 1 aron profile of both is obtained by selectively engraving the top end of the base layer. Figure 7A illustrates a preferred InGaP / GalnAsN DHBT structure having 33 1288479 with a transition layer, a layer and a lattice matching layer between the emitter and the base. There is a transition between the collector and the base

Graphical description of additional InGaP/GalnAsN

Figures 7B and 7C DHBT structures having a base layer of compositional composition. Figure 8 is a blend of growth at a fixed indium source gas flow rate.

11. The graph of the flow rate of Tmif to tetrabromocarbon required for the GalnAsN base layer of the composition of the doped slaves. Fig. 10 is a graph showing that the opening voltage of the InGaP / GalnAsN HBT is lower than that of the InGaP/GaAs HBT. Figure 11 is a graph of ΔVbe versus carbon tetrabromide flow rate in a carbon-doped GalnAsN base layer grown at a fixed TMIF. Figure 12 is a graph of Δ 乂 "for TMIF. Figure 13 is a DHBT structure having a compositionally graded base layer for the experiment of Example 2. Figure 14 is a base layer having a fixed composition for the experiment of Example 2. Figure 15 is a Gummel diagram comparing DHBT with a fixed composition of GalnAsN base layer and DHBT with a graded GalnAsN base layer. Figure 16 is a comparison of DHBT and composition with a fixed composition of GalnAsN base layer The DHBT of the graded GalnAsN base layer has a DC current gain as a function of the base sheet resistance. 1288479 Figure 17 is a Gummel plot comparing DHBT with a graded GalnAsN base layer and a GalnAsN base with a fixed composition Two DHBTs of the pole layer. Figure 18 is a graph comparing the DC current gain as a function of collector current density for a DHBT with a GalnAsN base layer composed of a graded structure and two DHBTs with a fixed composition of a GalnAsN base layer. 19 is a graph comparing a DHBT having a fixed composition of a GalnAsN base layer and a DHBT having a graded GalnAsN base layer, the extrapolation current gain cutoff frequency as a function of the collector current density. Comparing DHBT with a fixed composition of GalnAsN base layer and DHBT with a graded GalnAsN base layer, the small signal current gain is a function of frequency. Figure 21 is a comparison of DHBT with a fixed composition of GalnAsN base layer and DHBT with a graded GalnAsN base layer for a conventional HBT with a GaAs base layer, the peak ft of which is a function of BVce. Figure 22 shows a GalnAsN base layer with a gradation and a tunneling collector. Figure 23 is a diagram showing the band gap of the DHBT of Figure 22. Figure 24 is a Gummel diagram of the DHBT of Figure 22. Figure 25 shows the common emitter characteristics of the DHBT of Figure 22. ) Component symbol (none) 35

Claims (1)

Imm pick, patent scope: u A heterojunction bipolar transistor comprising: (a) an n-type doped collector; (b) a base formed on the collector and comprising a ΠΙ-ν family material, wherein ΙίΙ V private material includes indium and nitrogen, wherein the base is doped with carbon at a concentration of about Uxl 〇 19clr3 to about 7. 〇 xl 〇 19cir3, and wherein the composition of the base is graded to make indium and/or nitrogen The concentration at the base-collector interface is still at the base-emitter interface, whereby the base band gap is lower at the base-collector interface than at the base-emitter interface. a range of approximately 120 meV; and (c) an n-type doped emitter formed on the base. 2. A transistor as claimed in claim 1, wherein the base comprises gallium, indium, sand and nitrogen. 3. A transistor as claimed in claim 2, wherein the collector is GaAs' emitter is inGap, A1 InGaP or AlGaAs, and the transistor is a double heterojunction bipolar transistor. 4. The transistor of claim 1, wherein the energy band gap of the base layer is linearly graded from a surface where the base layer contacts the collector to a surface where the base layer contacts the emitter. 5. The transistor of claim 4, wherein the average band gap reduction of the graded base layer is less than about 20 meV to about 300 meV less than the band gap of the GaAs. ___ 6. The transistor of claim 5, wherein the average band gap reduction of the graded base layer is about 80 meV 36 1288479 to about 30 〇 meV less than the energy band gap of GaAs. 7. The transistor of claim 5, wherein the average band gap reduction of the graded base layer is less than about 20 meV to about 200 meV less than the band gap of the GaAs. 8. The transistor of claim 3, wherein the base layer comprises a layer of the formula GabxInxAsb yNy, wherein X and y are each independently from about 1·〇χ1〇-4 to about 2. 〇χ1 (Γΐ. 9. The transistor of claim 8 of the patent application, wherein x is approximately equal to 3y 〇10. The transistor of claim 8 of the patent scope, wherein the X value is approximately 〇·2 at the collector A range of approximately 〇·02, and is graded to the range of approximately 0.1 to approximately zero at the emitter, provided that χ is greater at the collector than at the emitter. 11·Calculator as in claim 10 Wherein 1 is approximately 〇·〇6 at the collector and approximately 〇〇1 at the emitter. 12· The transistor of claim 9 wherein the base layer is approximately 400 Α to approximately 1500 厚The sheet resistance is about 1 〇〇Ω/square to about 400 Ω/square. 13. The transistor of claim 12, wherein the concentration of the n-type dopant present in the emitter ranges from about 3 5 x 1 〇 17cm-3 to about 4·5χ1〇ιγ„Γ3, and the concentration range of n-type dopants present in the collector is large 9xl〇15CIir3 to about 2xl〇16cnr3. 14. The transistor of claim 13, wherein the emitter and the collector are doped with Shi Xi. 37 1288479 15 · If the patent application range is about 500A to about 750A thick Approximately 4500A thick. The 14-item transistor has a t-emitter and a collector of about 3500A to a maximum of 16. As in the patent of the 15th patent, the basin is filled with a + spoon and is disposed at the base and collector. (4) a first-transition layer, (four)-transition 2 having a first surface adjacent to the first surface of the base, wherein the first transition layer comprises a group selected from the group consisting of GaAs, InGaA〇InGaAsN: doped material. The transistor of claim 16, further comprising a second transition layer having a first surface adjacent to the first surface of the emitter and a second surface having a second surface adjacent to the base, The transition layer includes an n-type dopant material selected from the group consisting of GaAs, InGaAs, and InGaAsN. 18. The transistor of claim 17, further comprising a lattice matching layer having a layer adjacent to the collector a surface a surface and a second surface having a second surface adjacent to the first transition layer, wherein the lattice matching layer is a material having a wide band gap. ΘΒ 19. The transistor of claim 18, wherein the lattice matching layer A group selected from the group consisting of InGaP, AlInGaP, and A1 GaAs. 20. The transistor of claim 17, wherein the first and second transition layers are from about 40 A to about 60 A thick. The transistor of the item, wherein the first and second transition layers are about 40A to about 60A thick, and the lattice matching layer is about 150A to about 250A thick. 38 1288479 22· A method of fabricating a heterojunction bipolar transistor comprising the steps of: erbium (a) growing gallium, indium, arsenic and nitrogen sources on a n-doped GaAs collector layer, including gallium, a base layer of arsenic and nitrogen, wherein the base layer is made of an external carbon source and p-type doped with carbon, and the carbon doping concentration is about i 5xi〇i9cm_ 3 to about 7·〇χ1〇ΐ9(3)-3, and a base thereof The composition of the poles is graded such that the concentration of indium and/or nitrogen is higher at the base-collector interface than at the base-emitter interface, whereby the energy band gap of the base is at the base-collector The interface is at a range of about 2 〇 meV to about 12 〇 meV lower than at the base-emitter interface, and (b) an n-type doped emitter layer is grown on the base layer. 23. For example, the method of applying for patent paradigm 22, wherein the external carbon source is carbon tetrabromide or carbon tetrahydrate. 24. The method of claim 23, wherein the source of gallium is selected from the group consisting of trimethyl hydrazine and triethyl hydrazine. 25. The method of claim 24, wherein the source of nitrogen is ammonia, dimethyl hydrazine or tertiary butylamine. The ratio of the source of the source of the gallium is from about 2.0 to about 3.5. 27. The method of claim 26, wherein the base is grown at a temperature below about 750 °C. 28. The method of claim 27, wherein the base is grown at a temperature of from about 500 ° C to about 600 ° C. 29. The method of claim 27, wherein the base layer package 39 1288479 is a layer of GaixiMsi-yNy, wherein χ and y are independently from about i.Oxio-4 to about 2.0x10-, respectively. 30. The method of claim 29, wherein 1 is greater than 3y 〇 31. The method of claim 29, wherein the collector comprises: ^ the emitter comprises a material selected from the group consisting of 1_, AlInGaP, and A1GaAs. And wherein the transistor is a double heterojunction bipolar transistor. The method of claim 29, wherein the step of stepping in the first layer of the n-doped first transition layer on the collector layer before the base layer is grown, wherein the base layer is long On the n-type doped first transition layer, and the first-transition layer has a graded energy band gap or band gap smaller than the collector band gap. 33. The method of claim 32, wherein the first transition layer is selected from the group consisting of GaAs, InGaAs, and InGaAsN. 34. The method of claim 33, further comprising the step of growing a second transition layer on the base prior to growing the 11-doped emitter layer, wherein the second transition layer has a surface adjacent to the base The first surface and the second surface adjacent to the surface of the emitter, and the doping inversion of the second transition layer is at least one order of magnitude lower than the doping concentration of the emitter. 35. The method of claim 34, wherein the second transition layer is selected from the group consisting of GaAs, InGaAs, and InGaAsN. 36. The method of claim 35, wherein the first transition layer, the second transition layer, or both the first transition layer and the second transition layer 40 1288479 have doped peaks. 37. The method of claim 35, further comprising the step of growing a lattice matching layer on the collector before growing the n-type transition layer, wherein the lattice matching layer has a contiguous collector a first surface of the first surface and a second surface having a second surface adjacent to the first transition layer. 38. The method of claim 37, wherein the lattice matching layer comprises InGaP. 39. A method of forming a graded semiconductor layer, the graded semiconductor layer having a substantially linearly graded energy band gap from the first surface through the layer to the second surface and a substantially constant product of doping x mobility The method comprises the following steps: (a) Comparing the product of the doping X mobility of a plurality of correction layers, wherein each layer is an organometallic compound of a group or group V atom or a tetradentate of carbon deposited in a deposition period table. Formed at a clearly differentiated flow rate of any of the carbon compounds, thereby determining the relative flow rates of the organometallic compounds and tetra-self-carbons required to form a substantially constant doping x-movement product. And (b) flowing the organometallic compound and the tetra-n-carbon compound on a surface at the relative flow rate to form a product of substantially constant doping X mobility, which is changed during deposition The flow rate, thereby forming a substantially linear band gap in the entire graded semiconductor layer. 40. The method of claim 39, further comprising the step of depositing the graded layer on the second semiconductor layer during fabrication of the bond. 1288479 41 • As claimed in the patent area, the body layer is the collector layer. 42. If the scope of the patent application is the emitter layer. The method of item 40, wherein the second half of the method of 40, wherein the second half is 43. The method of claim 帛 39帛, wherein the graded semiconductor layer comprises gallium, indium, and kun' and determines (four) The organometallic compound having a deposition rate to form a substantially constant doping x mobility product includes an organic indium compound. σ 44. The method of claim 41, wherein the tetradentate carbon 45. The method of claim 44 (4), wherein the compound further comprises a nitrogen source gas. The method of claim 46, wherein the second semiconductor layer on which the graded semiconductor layer is deposited comprises GaAs. 47. The method of claim 46, wherein the method further comprises the step of depositing a third semiconductor layer on the graded semiconductor layer. The method of item 47, wherein the third half is 48. The body layer of the patent application is InGaP. 49. The method of claim 46, wherein the doping X mobility product of each of the correction layers is associated with an energy band gap, whereby the band gaps at the first and second surfaces are combined with the band gap The dopant movement center will correct the relative flow rate of the organometallic 3 and tetrahalide carbon required to deposit the graded semiconductor layer. 5. The method of claim 49 (4) is such that the gap between the energy bands 42 1288479 is corrected relative to GaAs to the base-emitter voltage of the bonding element using the correction layer as the base layer. The method of claim 50, wherein the formed and the semiconductor layer are heterogeneously bonded to the base layer in the bipolar transistor. ," the method of Patent No. 51, the flow rate of the organometallics and the θ-toothed carbon in the crucible causes the resulting fractional ▼ gap from the base soil of the heterojunction bipolar transistor, and the monthly b/collar junction Reduced. /The emitter is connected to the base and the 囷: as the next page.