Disclosure of Invention
Therefore, the invention provides a new structure of the silicon germanium photoelectric detector, and the silicon germanium photoelectric detector is integrated with an adjustable bandwidth gain component, so that the gain peak value can be adjusted through the component, and the silicon germanium photoelectric detector has the optimal bandwidth gain.
Specifically, the technical scheme of the invention is as follows:
the invention provides a germanium-silicon photoelectric detector with an adjustable gain peak, which comprises the following components from bottom to top: the silicon-germanium photoelectric detector comprises a silicon substrate layer, a buried oxide layer, a silicon waveguide layer, a germanium active layer and an insulating covering layer, and is characterized by further comprising an adjustable bandwidth gain component arranged on the germanium active layer.
Further, the tunable bandwidth gain component includes a graphene signal conductor and a control electrode spaced apart by a predetermined distance, and the control electrode is configured to apply a voltage to the graphene signal conductor to achieve a tunable matching inductance.
According to one embodiment, the graphene signal conductor is in direct contact with the germanium active layer.
According to one embodiment, the graphene signal wire has a folded-back U-shape or a clip-shape.
According to one embodiment, the graphene signal conductor may be integrated with a silicon germanium photodetector using a transfer method.
According to one embodiment, the control electrode is located directly above the graphene signal conductor and has the same orientation as the graphene signal conductor.
According to one embodiment, the silicon waveguide layer has a spot conversion structure.
According to one embodiment, the silicon germanium photodetector further comprises a protective layer located on the outermost layer.
According to the germanium-silicon photoelectric detector with the adjustable bandwidth gain component, the problem of difference of bandwidth gain parameters caused by difference of different individuals of the germanium-silicon photoelectric detector can be solved through the adjustable bandwidth gain component, and the optimal bandwidth gain of each germanium-silicon photoelectric detector is realized.
Detailed Description
In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the drawings of the embodiments of the present invention. It is to be understood that the embodiments described are only a few embodiments of the present invention, and not all embodiments. All other embodiments, which can be derived by a person skilled in the art from the described embodiments of the invention without any inventive step, are within the scope of protection of the invention.
Unless defined otherwise, technical or scientific terms used herein shall have the ordinary meaning as understood by those skilled in the art to which the invention pertains. The word "comprising" or "comprises", and the like, in this disclosure is intended to mean that the element or item listed before the word covers the element or item listed after the word and its equivalents, but does not exclude other elements or items. The terms "connected" or "coupled" and the like are not restricted to physical or mechanical connections, but may include electrical connections, whether direct or indirect. "upper", "lower", "left", "right", and the like are used merely to indicate relative positional relationships, and when the absolute position of the object being described is changed, the relative positional relationships may also be changed accordingly.
It should be noted that the thicknesses, sizes and shapes of the various layer structures in the drawings do not reflect the true scale of the photodetector, and are merely illustrative of the present disclosure.
An embodiment of the present invention provides a silicon germanium photodetector, and referring to fig. 1 to fig. 2, fig. 1 is an isometric view of a bandwidth-enhanced silicon germanium photodetector with an adjustable gain peak in an embodiment of the present invention, and fig. 2 is a side view of a bandwidth-enhanced silicon germanium photodetector with an adjustable gain peak in an embodiment of the present invention.
In one embodiment, the silicon germanium photodetector is stacked with a silicon substrate layer 100, a silicon buried oxide layer 110, a silicon waveguide layer 120, a germanium active layer 130, an insulating cap layer 140a, and a tunable bandwidth gain component 150 from bottom to top in sequence.
In a specific embodiment, the tunable bandwidth gain module 150 includes a signal conductor 1501, and a control electrode 1502.
The structure and the manufacturing method of the germanium-silicon photoelectric detector with adjustable gain peak according to the present invention will be described in detail below with reference to the accompanying drawings.
The Silicon germanium photodetector in this embodiment is manufactured based On a mature Silicon On Insulator (SOI) process. SOI comprises a back substrate 100, a buried oxide layer 110, and a silicon waveguide layer 120.
Using an SOI process, a desired silicon waveguide is fabricated on the silicon waveguide layer 120 for receiving an optical signal and guiding the propagation direction of the optical signal. The geometry of the silicon waveguide layer 120 is arbitrary and may be selected according to the actual application of the photodetector, such as a slab, strip or ridge waveguide structure. In one embodiment, a tapered waveguide structure such as that shown in FIG. 1 is selected for mode spot conversion.
Generally, in order to couple an optical signal into a waveguide layer and improve the coupling efficiency of a silicon optical device with the inside and the outside, a Spot Size Converter (SSC) or a Spot Size Converter is generally designed in a silicon waveguide. At present, the spot size converters generally used include, but are not limited to, forward tapered spot size converters, reverse tapered spot size converters, multi-stage tapered spot size converters, multi-waveguide spot size converters, three-dimensional tapered spot size converters, and the like.
Next, a germanium active layer 130 is grown on the silicon waveguide layer 120, which receives the optical signal from the silicon waveguide layer 120, converts the optical signal into an electrical signal, and is output from the upper surface of the germanium active layer 130.
Further, the silicon waveguide layer 120 and the germanium active layer 130 are first completely covered with the insulating capping layer 140a, and then the thickness of the insulating capping layer 140a is appropriately thinned until the top portion of the germanium active layer 130 is exposed. The insulating cap layer 140a is typically SiO, which is commonly used in the art2Materials, but not limited thereto.
In the prior art, a metal wire inductor connected with a germanium active layer is further manufactured on the basis of a stacked structure formed by a silicon substrate layer, a silicon buried oxide layer, a silicon waveguide layer, a germanium active layer and an insulating cover layer to form a germanium-silicon photoelectric detector.
However, the present inventors have found that there is a problem in that performance of the silicon germanium photodetector varies between different individuals. Although reducing or eliminating the variation among different elements of the sige photodetector can be partially solved by optimizing the manufacturing process or improving the manufacturing accuracy, it is very demanding for the related equipment and process. Even so, this approach still cannot completely eliminate the problem of bandwidth performance difference existing between sige photodetector products.
Therefore, the invention provides the germanium-silicon photoelectric detector with the adjustable bandwidth gain component, which can optimize the bandwidth characteristics of each germanium-silicon photoelectric detector by optimally configuring each germanium-silicon photoelectric detector under the existing equipment and conventional manufacturing requirements. Specifically, the adjustable bandwidth gain component provided by the invention comprises a graphene signal wire and a control circuit, wherein an electric signal output by the germanium-silicon photoelectric detector is transmitted in the graphene signal wire, different voltages are applied to the graphene signal wire through the control circuit, and the inductance value of the graphene signal wire is changed, so that the bandwidth gain of the germanium-silicon photoelectric detector provided by the invention can be adjusted, and the bandwidth performance of the germanium-silicon photoelectric detector provided by the invention is optimized. And because the bandwidth gain of the germanium-silicon photoelectric detector can be adjusted within a certain range through the bandwidth gain component, even if certain inconsistency exists among different germanium-silicon photoelectric detector individuals, the required optimized bandwidth gain can be achieved by applying proper voltage to the graphene signal wire. Therefore, the performance of the germanium-silicon photoelectric detector has a remarkable improvement effect.
The structure and fabrication method of the sige photodetector with tunable bandwidth gain module according to the present invention will be described below.
Specifically, the tunable bandwidth gain element 150 is fabricated on the above-mentioned stacked structure of the silicon substrate layer 100, the buried oxide layer 110, the silicon waveguide layer 120, the germanium active layer 130, and the insulating cap layer 140 a.
The method and principles of making the tunable bandwidth gain module 150 of the present invention will be described in detail below.
In order to make the signal wire have enhanced inductance characteristics, the invention particularly uses a graphene signal wire, and particularly the graphene signal wire adopts a U-shaped turn-back-shaped routing, as shown in FIG. 1, and the graphene signal wire arranged in such a way has a wider inductance adjusting space.
The signal wire 1501 prepared in advance is transferred to the stacked structure of the silicon substrate layer 100, the buried oxide layer 110, the silicon waveguide layer 120, the germanium active layer 130, and the insulating cap layer 140a through a conventional transfer process, and is connected to the exposed portion of the germanium active layer 130, whereby an electrical signal output from the germanium active layer 130 is introduced into the signal wire 1501.
Subsequently, the germanium active layer 130 and the signal wire 1501 are again covered with the insulating cover layer 140b is covered. Preferably, the insulating cover layer 140b covering the signal wire 1501 uses the same material as the insulating cover layer 140a used above for covering the silicon waveguide layer 120, i.e., SiO2A material. In terms of form, the two-time formed cladding layers (i.e. 140a, 140b) of the silicon germanium photodetector of the present invention are formed in an integrated manner, completely encapsulating the silicon buried oxide layer 110, the silicon waveguide layer 120, the germanium active layer 130 and the signal wire 1501.
Finally, a control electrode 1502 is fabricated on the above structure. It will be appreciated that the control electrode 1502 is formed on the insulating cap layer 140 b.
Control electrodes 1502 are sized and routed in accordance with signal conductors 1501. Note that the control electrode 1502 should be disposed directly above the graphene signal wire 1501.
Control electrode 1502 is made of a highly conductive material, such as a material selected from copper, gold, or aluminum.
It will be appreciated that the control electrodes 1502 and signal conductors 1501 are separated by an insulating cover layer 140 b. A person skilled in the art can set the predetermined distance of the interval, i.e., adjust the height of the portion of the insulating cover layer 140b above the signal wire 1501, according to the inductance of the graphene signal wire, the voltage range of the control electrode, the inductance target range of the signal wire, and the like.
Since the dynamic inductance of the graphene signal wire is related to the graphene electron transport state, which can be adjusted by the gate voltage, different voltages v (as shown in fig. 2) can be applied to the graphene signal wire 1501 located right below through the control electrode 1502 to change the gate voltage of the graphene, so as to change the inductance value of the graphene signal wire 1501, and thus obtain a desired or predetermined bandwidth gain.
A protective layer (not shown in the figure) may also be formed on the outermost layer of the stacked structure of the above-described sige photodetector. In specific application, SiO can be selected2As a material for the protective layer.
The germanium-silicon photoelectric detection integrated with the adjustable bandwidth gain component provided by the invention can flexibly change the gain peak effect aiming at different transmission links in the application of a transmission system, thereby optimizing the working parameters and the system performance of a photoelectric device.
Finally, it should be noted that the above-mentioned embodiments are only for illustrating the technical solutions of the present invention and not for limiting, and it should be understood by those skilled in the art that modifications or equivalent substitutions can be made on the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, which should be covered by the claims of the present invention.