JPH07297494A - Gallium nitride compound semiconductor laser diode - Google Patents

Abstract

(57) [Abstract] [Purpose] To reduce the oscillation threshold current of a laser. A double heterojunction structure gallium nitride compound semiconductor ((Al _x Ga _1-x ) _y In _{1-y in} which an active layer 5 is sandwiched between layers 4 and 6 having a forbidden band width larger than the forbidden band width N: 0 ≦ x ≦ 1,
In the laser diode composed of 0 ≦ y ≦ 1), the active layer 5 is formed by adding Si to a gallium nitride-based compound semiconductor ((Al _x Ga _1-x ) _y In _1-y N: 0 ≤x≤1,0 ≤y ≤1)
Formed by. As a result, the light emission efficiency was improved and the oscillation threshold current was decreased.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor laser diode capable of emitting light in the single visible wavelength range, particularly in the blue range to the violet range, and in the ultraviolet range, and more particularly to a laser with a reduced oscillation threshold current. Regarding

[0002]

2. Description of the Related Art Conventionally, a laser diode described in Japanese Patent Laid-Open No. 4-242985 has been proposed. The laser diode is a gallium nitride compound semiconductor ((Al _x Ga _1-x ) _y In _1-y N: 0
≦ x ≦ 1,0 ≦ y ≦ 1), and a layer without impurities is used as the active layer.

[0003]

Therefore, there is a problem that the emission efficiency between bands is poor and the threshold current for laser oscillation is high.

The present invention was made to solve the above problems, and an object of the present invention is to reduce the threshold current of laser oscillation.

[0005]

The structure of the invention for solving the above-mentioned problems is a gallium nitride compound semiconductor having a double heterojunction structure in which an active layer is sandwiched by layers having a forbidden band width larger than the forbidden band width. ((Al _x Ga _1-x ) _y In _1-y N: 0 ≦ x ≦ 1,
0 ≦ y ≦ 1), the active layer of the gallium nitride compound semiconductor ((Al _x Ga _1-x ) _y In _1-y N: 0 ≦ It is characterized in that x ≦ 1,0 ≦ y ≦ 1).

[0006]

[Operation and effect] The active layer is a gallium nitride-based compound semiconductor ((Al _x Ga _1-x ) _y In containing Si-doped n-type conductivity.
_1-y N: 0 ≤ x ≤ 1, 0 ≤ y ≤ 1), so that the luminous efficiency of the active layer can be improved and the threshold current of oscillation can be reduced.

[0007]

EXAMPLES The present invention will be described below based on specific examples.

FIG. 1 is a sectional view showing the structure of a semiconductor laser diode using a sapphire substrate. In FIG. 1, a sapphire substrate 1 having a (0001) plane as a crystal growth plane is washed with an organic material and then placed in a crystal growth unit of a crystal growth apparatus.
After evacuation of the growth furnace, hydrogen is supplied and the temperature is raised to about 1200 ° C. As a result, the hydrocarbon gas attached to the surface of the sapphire substrate 1 is removed to some extent.

Next, the temperature of the sapphire substrate 1 is lowered to about 400 ° C., trimethylaluminum (TMA) and ammonia (NH ₃ ) are supplied, and the AlN layer 2 having a film thickness of about 50 nm is formed on the sapphire substrate 1. To form.

Next, the supply of TMA is stopped and the substrate temperature is set to 11
Raise it to 50 ℃, and add trimethylgallium (TMG)
iH ₄ ) is supplied to grow a Si-doped n-type GaN layer 3 (n ⁺ layer).

Once the wafer is taken out of the growth furnace, GaN
After masking a part of the surface of the layer 3 with SiO ₂ , the layer 3 is returned to the growth furnace and evacuated to supply hydrogen and NH ₃ to raise the temperature to 1150 ° C.

Next, TMA and TMG are supplied to add 0.5 μm-thick undoped Al to the portion not masked with SiO _{2.
A 0.1} Ga _0.9 N layer 4 (n layer) is formed.

Next, TMG and silane (SiH ₄ ) are supplied to grow a GaN layer 5 (active layer) having a thickness of 0.4 μm and added with silicon (Si).

Next, by supplying TMA, TMG and Cp ₂ Mg,
Al _0.1 Ga _0.9 N layer 6 with a thickness of 0.5 μm and containing magnesium
(P layer) is formed. Next, SiO ₂ used as a mask
Are removed with a hydrofluoric acid-based etchant.

Next, SiO _{2 is formed} on the Al _0.1 Ga _0.9 N layer 6 (p layer).
After depositing the layer 7, the window 7A is formed into a strip with a length of 1 mm and a width of 50 μm.
Open and transfer to a vacuum chamber, and the Al _0.1 Ga _0.9 N layer 6 (p layer) to which magnesium is added is subjected to electron beam irradiation treatment under the following conditions. By this electron beam irradiation, Al _0.1 Ga _0.9
The N layer 6 (p layer) showed p-type conduction.

[0016]

[Table 1]

Next, the window 7A of the Al _0.1 Ga _0.9 N layer 6 (p layer) is formed.
And the GaN layer 3 (n ⁺ layer) are formed with metal electrodes 8A and 8B, respectively.

In this way, a laser diode was produced. This laser diode has an oscillation threshold current of 90% as compared with the laser diode in which the GaN layer 5 (active layer) is not added.
Fell to%.

Although the sapphire substrate 1 is used in the above embodiment, a silicon substrate, a 6H-SiC substrate or a GaN substrate may be used.

[Brief description of drawings]

FIG. 1 relates to a specific example of the present invention formed on a sapphire substrate ((Al _x Ga _1-x ) _y In _1-y N: 0 ≦ x ≦ 1,0 ≦ y ≦ 1)
FIG. 3 is a cross-sectional view showing the configuration of a semiconductor laser diode.

[Explanation of symbols]

1 ... Sapphire (0001) plane substrate 2 ... AlN buffer layer 3 ... GaN layer (n ⁺ layer) 4 ... Al _0.1 Ga _0.9 N layer (n layer) 5 ... GaN layer (active layer) 6 ... Al _0.1 Ga _0.9 N Layer (p layer) 7 ... SiO ₂ layer 8A, 8B ... Electrode

 ─────────────────────────────────────────────────── ─── Continuation of the front page (71) Applicant 591014950 Hiroshi Amano 2-chome Yamanote, Meito-ku, Nagoya, Aichi 104 Takara Mansion Yamanote 508 (72) Inventor Shiro Yamazaki 1 Nagahata, Ochiai, Kasuga-cho, Nishikasugai-gun, Aichi Prefecture Toyota Synthetic Co., Ltd. (72) Inventor Norikatsu Koide 1 Ochiai, Nagahata, Kasuga-cho, Nishikasugai-gun, Aichi Prefecture Toyota Synthetic Co., Ltd. (72) Inventor Hiroshi Amano Room No. 103, Bldg. 19, Nijigaoka Higashi Danchi, 21-21 Kamioka-cho, Meito-ku, Nagoya, Aichi

Claims (1)

[Claims] 1. A gallium nitride-based compound semiconductor ((Al _x Ga _1-x ) _y In _1-y N: having a double heterojunction structure in which an active layer is sandwiched between layers having a forbidden band width larger than the forbidden band width. 0 ≤ x ≤ 1,0
≦ y ≦ 1), wherein the active layer is a gallium nitride-based compound semiconductor ((Al _x Ga _1-x ) _y In _1-y N: 0 ≦ with Si-doped n-type conductivity. x ≦ 1,0 ≦
A gallium nitride-based compound semiconductor laser diode formed by y ≤ 1).