JPH08213655A - Gallium nitride compound semiconductor light emitting device - Google Patents

Abstract

(57) [Abstract] [Purpose] Improving the luminous efficiency of N-type GaN-based compound semiconductor light-emitting devices with controlled resistivity [Constitution] A 500 Å AlN buffer layer 2 is formed on a sapphire substrate 1 and its In the order above, a film thickness of about 2.2 μm, a high carrier concentration N ⁺ layer 3 of GaN with an electron concentration of 1.5 × 10 ¹⁸ / cm ³ doped with silicon, a film thickness of about 1.5 μm, an electron concentration of 1 × 10
GaN low carrier concentration N layer 4 of ¹⁵ / cm ³ or less, film thickness about 0.2
An I layer 5 of μm GaN is formed. Electrodes 7 and 8 made of aluminum are formed on the I layer 5 and the high carrier concentration N ⁺ layer 3, respectively.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a blue light emitting gallium nitride compound semiconductor light emitting device having improved light emitting efficiency.

[0002]

2. Description of the Related Art Conventionally, GaN-based compound semiconductors have been used for blue light emitting diodes. The GaN-based compound semiconductor is attracting attention because it has a high emission efficiency because it is a direct transition and because blue, which is one of the three primary colors of light, is the emission color.

A light-emitting diode using such a GaN-based compound semiconductor has an N-type Ga directly on a sapphire substrate or with a buffer layer made of aluminum nitride interposed.
It has a structure in which an N layer made of an N 2 -based compound semiconductor is grown, and an I layer made of an I-type GaN-based compound semiconductor is grown by adding a P-type impurity on the N layer (Japanese Patent Application Laid-Open No. 2000-242242). Akira
62-119196, JP-A-63-188977).

[0004]

In manufacturing the light emitting diode having the above structure, the junction between the I layer and the N layer is used. When a GaN-based compound semiconductor is manufactured, the GaN-based compound semiconductor usually has an N conductivity type even if it is not intentionally doped with impurities, and conversely, unlike a semiconductor such as silicon, To obtain an (Insulator) type semiconductor, zinc was doped. Further, when obtaining N-type GaN, it was difficult to control the conductivity thereof.

However, in the process of manufacturing the above-mentioned GaN light emitting diode, the present inventor has established a vapor phase growth technique for a GaN semiconductor by a metalorganic vapor phase epitaxy method, and has developed a high purity GaN vapor phase growth film. I was able to get it. As a result, conventionally, when impurity doping is not performed,
Although N-type GaN with low resistivity was obtained, GaN with high resistivity was obtained without doping impurities by establishing vapor phase growth technology by the present inventors.

On the other hand, in the future, in order to improve the characteristics of the above-mentioned GaN light emitting diode, it is necessary to obtain a vapor phase growth film of a GaN-based compound semiconductor whose conductivity can be controlled intentionally. Therefore, it is an object of the present invention to improve the luminous efficiency of a light emitting device having a GaN compound semiconductor layer by controlling the resistivity by silicon doping.

[0007]

According to a first aspect of the present invention, in a light emitting device having a gallium nitride-based compound semiconductor (including Al _X Ga _1-X N; X = 0), silicon-doped nitriding is used. It is characterized by having a gallium compound semiconductor (including Al _X Ga _1-X N; X = 0).

According to a second aspect of the present invention, there is provided a gallium nitride-based compound semiconductor (Al _X Ga) formed on a sapphire substrate.
_1-X N; including X = 0), a silicon-added gallium nitride-based compound semiconductor (Al _X Ga _1-X N; X
(Including = 0).

According to a third aspect of the present invention, a light emitting device having a gallium nitride-based compound semiconductor (including Al _X Ga _{1 -X} N; X = 0) formed on a buffer layer formed on a sapphire substrate. In gallium nitride-based compound semiconductor (including Al _X Ga _{1 -X} N; X = 0) to which silicon is added.

The invention according to claim 4 is characterized in that an extraction electrode is formed on a gallium nitride-based compound semiconductor (Al _X Ga _{1 -X} N; including X = 0) to which silicon is added. To do.

According to a fifth aspect of the invention, the resistivity of the gallium nitride compound semiconductor (Al _X Ga _1-X N; including X = 0) to which silicon is added has a resistivity of 3 × 10 ^-1 Ωcm-8 ×. It is characterized by being 10 ⁻³ Ωcm.

[0012]

INDUSTRIAL APPLICABILITY The present invention makes it possible to dope silicon in a light emitting device having a gallium nitride-based compound semiconductor layer (including Al _X Ga _1-X N; X = 0), and to improve the resistivity of the layer. As a result of making controllable, a gallium nitride-based compound semiconductor layer (including Al _X Ga _1-X N; X = 0) with controlled resistivity could be obtained with high accuracy. As a result, the luminous efficiency of the light emitting element could be improved.

[0013]

EXAMPLES The present invention will be described below based on specific examples. The light emitting diode 10 having the structure shown in FIG. 1 was manufactured using the manufacturing method of the present invention.

In FIG. 1, the light emitting diode 10 has a sapphire substrate 1, and the sapphire substrate 1 has a sapphire substrate 1.
A buffer layer 2 of 0Å AlN is formed. On the buffer layer 2, a high carrier concentration N ⁺ layer 3 of GaN having a film thickness of about 2.2 μm and a low carrier concentration N layer 4 of GaN having a film thickness of about 1.5 μm are sequentially formed. Further, an I layer 5 made of GaN having a film thickness of about 0.2 μm is formed on the low carrier concentration N layer 4. Then, the electrode 7 formed of aluminum and connected to the I layer 5 and the high carrier concentration N ⁺
An electrode 8 made of aluminum is formed which is connected to the layer 3.

Next, a method of manufacturing the light emitting diode 10 having this structure will be described. The light emitting diode 10 is
It was manufactured by vapor phase growth by an organometallic compound vapor phase growth method (hereinafter referred to as “M0VPE”). The gas used was NH
₃ and the carrier gas H ₂ and trimethylgallium (Ga (CH _{3) 3)}
(Hereinafter referred to as "TMG") and trimethylaluminum (Al
(CH _{3) 3)} (a hereinafter referred to as "TMA") and silane (SiH ₄₎ and diethyl zinc (hereinafter referred to as "DEZ").

First, the single crystal sapphire substrate 1 whose main surface is the a-plane cleaned by organic cleaning and heat treatment is mounted on the susceptor placed in the reaction chamber of the M0VPE apparatus. Then H ₂
Was flown into the reaction chamber at a flow rate of 2 l / min, and the sapphire substrate 1 was vapor-phase etched at a temperature of 1200 ° C. for 10 minutes. Next, the temperature was lowered to 400 ° C., H ₂ was flown at 20 l / min, NH ₃ was flown at 10 l / min, and TMA kept at 15 ° C. was bubbled into H ₂
Was supplied at 50 cc / min to form an AlN buffer layer 2 having a thickness of about 500Å.

Next, the supply of TMA is stopped, the temperature of the sapphire substrate 1 is maintained at 1150 ° C., H ₂ is 20 l / min, NH ₃ as another source gas is 10 l / min, and − of H ₂ which was bubbled TMG kept at 15 ℃ flowed at 100 cc / min, silane diluted with H ₂ to 0.86ppm as a gas containing silicon (SiH ₄₎ and 30 shunted 200ml / min, thickness About 2.2 μm,
To form a high carrier concentration N ⁺ layer 3 made of GaN having a carrier concentration 1.5 × 10 ¹⁸ / cm ^3.

Then, the temperature of the sapphire substrate 1 is set to 1150 ° C.
, H ₂ 20 l / min, NH ₃ 10 l / min, -15 ℃
Of H ₂ which was bubbled TMG held at 100 cc / min to 20
Flowing for 1 minute, film thickness about 1.5μm, carrier concentration 1 × 10 ¹⁵ / c
A low carrier concentration N layer 4 made of GaN of m ³ or less was formed.

Next, the sapphire substrate 1 is set to 900 ° C.,
H ₂ at 20 l / min, NH ₃ at 10 l / min, TMG at 1.7 × 10 ⁻⁴ mol / min and DEZ at 1.5 × 10 ⁻⁴ mol / min,
An I layer 5 made of GaN having a film thickness of 0.2 μm was formed. In this way, a multilayer structure as shown in FIG. 2 was obtained. Next, as shown in FIG. 3, a SiO ₂ layer 11 having a thickness of 2000 Å was formed on the I layer 5 by sputtering. Next, a photoresist 12 was applied on the SiO ₂ layer 11, and the photoresist 12 was formed by photolithography into a pattern in which the photoresist at the electrode formation site for the high carrier concentration N ⁺ layer 3 was removed.

Next, as shown in FIG. 4, the SiO ₂ layer 11 not covered with the photoresist 12 was removed with a hydrofluoric acid-based etching solution. Next, as shown in FIG. 5, a part of the upper surface of the I layer 5 in a portion not covered by the photoresist 12 and the SiO ₂ layer 11, the low carrier concentration N layer 4 and the high carrier concentration N ⁺ layer 3 thereunder. Was vacuum-dried at a rate of 0.04 Torr, high-frequency power of 0.44 W / cm ² , and CCl ₂ F ₂ gas was supplied at 10 ml / min for dry etching, followed by dry etching with Ar. next,
As shown in FIG. 6, the SiO ₂ layer 11 remaining on the I layer 5 was removed with hydrofluoric acid.

Next, as shown in FIG.
The Al layer 13 was formed by vapor deposition. And the Al layer 13
Photoresist 14 is applied on top of it, and the photoresist 14 has a high carrier concentration N by photolithography.
^A pattern was formed in a predetermined shape so that the electrode portions for the ⁺ layer 3 and the I layer 5 remained. Next, as shown in FIG. 7, using the photoresist 14 as a mask, the exposed portion of the lower Al layer 13 is etched with a nitric acid-based etching solution, the photoresist 14 is removed with acetone, and the high carrier concentration N ⁺ layer 3 is removed. An electrode 8 and an electrode 7 of the I layer 5 were formed.

In this way, the MIS (Me with the structure shown in FIG.
It is possible to manufacture a gallium nitride-based luminescent element having a ta-l-Insulator-Semiconductor) structure. In the above manufacturing process, when the high carrier concentration N ⁺ layer 3 is vapor-phase grown, H ₂
20 l / min, NH ₃ as another source gas 10 l / min, and H ₂ bubbling TMG held at -15 ℃
Flowing at c / min and controlling the silane (SiH ₄ ) diluted with H ₂ to 0.86 ppm as a gas containing silicon in the range of 10 cc / min to 300 cc / min, the high carrier concentration N ⁺ layer 3 As shown in Fig. 8, the resistivity is from 3 × 10 ^-1 Ωcm to 8 × 10 ^-3.
It can be changed up to Ωcm.

In the above method, silane (SiH ₄ ) was controlled, but the flow rates of other source gases may be controlled, and the mixture ratio of both may be controlled to change the resistivity. Although silane was used as the Si dopant material in this example, an organic compound containing Si such as tetraethylsilane is used.
A gas obtained by bubbling (Si (C ₂ H ₅ ) ₄ ) or the like with H ₂ may be used. In this way, the high carrier concentration N ⁺ layer 3 and the low carrier concentration N layer 4 could be formed in a state where the resistivity could be controlled.

As a result, the light emitting intensity of the light emitting diode 10 manufactured by the above method is 0.2 mcd, which is four times as high as the light emitting intensity of the conventional light emitting diode including the I layer and the N layer. When the light emitting surface was observed, it was also observed that the number of light emitting points increased.

[Brief description of drawings]

FIG. 1 is a configuration diagram showing a configuration of a light emitting diode according to a specific embodiment of the present invention.

FIG. 2 is a cross-sectional view showing a manufacturing process of the light emitting diode of the same embodiment.

FIG. 3 is a cross-sectional view showing a manufacturing process of the light emitting diode of the same embodiment.

FIG. 4 is a sectional view showing a manufacturing process of the light emitting diode of the same embodiment.

FIG. 5 is a cross-sectional view showing a manufacturing process of the light emitting diode of the same embodiment.

FIG. 6 is a sectional view showing a manufacturing process of the light emitting diode of the embodiment.

FIG. 7 is a sectional view showing a manufacturing process of the light emitting diode of the same embodiment.

FIG. 8 is a measurement diagram showing the relationship between the flow rate of silane gas and the electrical characteristics of a vapor-grown N layer.

[Explanation of symbols]

10 ... Light emitting diode 1 ... Sapphire substrate 2 ... Buffer layer 3 ... High carrier concentration N ⁺ layer 4 ... Low carrier concentration N layer 5 ... I layer 7, 8 ... Electrode

 ─────────────────────────────────────────────────── ─── Continuation of the front page (71) Applicant 390014535 New Technology Corporation 4-8-8 Honmachi, Kawaguchi City, Saitama Prefecture (72) Inventor Sasa Dosei, Nagasaki, Kasuga Town, Nishikasugai District, Aichi Prefecture In-house (72) Inventor Masahide Masabe 1 Ochiai, Nagachi, Kasuga-cho, Nishikasugai-gun, Aichi Toyoda Gosei Co., Ltd. (72) Inventor Kuki, Kasuga-cho, Nishi-Kasugai-gun, Aichi 1 Ochiai, Nagahata 1 Toyoda Gosei Co., Ltd. Inventor Yu Akasaki Furo-cho, Chikusa-ku, Nagoya, Aichi Prefecture (no street number) Inside Nagoya University

Claims (5)

[Claims] 1. A gallium nitride-based compound semiconductor (Al _X Ga
_1-X N; including X = 0), a silicon-doped gallium nitride-based compound semiconductor (Al _X
Ga _1-X N; including X = 0). 2. A light emitting device having a gallium nitride-based compound semiconductor (including Al _X Ga _1-X N; X = 0) formed on a sapphire substrate, wherein a gallium nitride-based compound semiconductor (Al _X
Ga _1-X N; including X = 0). 3. A gallium nitride based compound semiconductor (Al _X Ga) formed on a buffer layer formed on a sapphire substrate.
_1-X N; including X = 0), a silicon-doped gallium nitride-based compound semiconductor (Al _X
Ga _1-X N; including X = 0). 4. The extraction electrode is formed on the gallium nitride-based compound semiconductor (Al _X Ga _1-X N; including X = 0) to which the silicon is added. Light emitting element. 5. The resistivity of the gallium nitride-based compound semiconductor to which silicon is added (including Al _X Ga _1-X N; X = 0) has a resistivity of 3 ×.
The light emitting device according to claim 1, wherein the light emitting device has a density of 10 ^-1 Ωcm-8 × 10 ^-3 Ωcm.