JPH09219538A - 3-group nitride semiconductor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To accomplish improvement both in luminous intensity and in bluing emitted light. SOLUTION: An AIN buffer layer 2 of 500Å is formed on a sapphire substrate 1. A silicon-doped GaN high carrier density n<+> layer 3 of about 2.0μm in film thickness and electron density of 2×10<18> /cm<3> , a silicon-doped (Alx2 Ga1-x2 )y2 In1-y2 N high carrier density n<+> layer 4 of about 2.0μm in film thickness and electron density of 2×10<18> cm<3> , a zinc and silicon-deped (Alx1 Ga1-x1 )y1 In1-y1 N n-layer (light emitting later) 5 of about 0.5 μm in film thickness, and a magnesium-doped (Alx2 Ga1-x2 )y2 In1-y2 N P-layer 6 of about 1.0μm in film thickness and hole density of 2×10<17> /cm<3> are formed successively on the buffer layer 2. Nickel electrodes 7 and 8, to be connected to the above-mentioned P-layer 6 and high carrier density<+> layer 4, are formed. They are electrically insulation- isolated by a groove 9. The ratio of components of Al, Ga and In of the layers 4, 5 and 6 is selected in such a manner that the lattice constant of each layer is coincided with the lattice constant of the layer 3.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a light emitting device using a group III nitride semiconductor.

[0002]

2. Description of the Related Art Conventionally, AlGaIn has been used as a blue light emitting diode.
A device using an N-based compound semiconductor is known. The compound semiconductor has attracted attention because of its direct transition type, which has high luminous efficiency, and that one of the three primary colors of light, blue, is used as the luminescent color.

Recently, it has been revealed that an AlGaInN-based semiconductor can be made p-type by doping with Mg and irradiating an electron beam or by heat treatment. As a result, instead of the conventional MIS type in which an n-layer and a semi-insulating layer (i-layer) are joined, AlGaN
, A Zn-doped GaInN light emitting layer, and an AlGaN n layer have been proposed as a light emitting diode having a double hetero pn junction.

[0004]

The above-mentioned double hetero p
In the n-junction type light emitting diode, the light emitting layer is doped with Zn as an emission center. Although the light emitting diode of this type has a considerably improved light emission intensity, further improvement of the light emission intensity is desired. As described above, in the conventional light emitting device, only the acceptor impurities of magnesium (Mg) or zinc (Zn) are added to the light emitting layer. For this,
The emission mechanism of this device is due to the transition between the conduction band and the acceptor level. However, since the energy level difference is large, non-radiative recombination via other deep levels becomes dominant. , The emission intensity is not high. The emission peak wavelength is 380 to 440 nm, which is slightly shifted to the short wavelength side with respect to pure blue. The present invention has been made to solve the above problems, and an object thereof is to improve the light emission intensity of a light emitting device using an AlGaInN semiconductor and obtain a spectrum closer to pure blue.

[0005]

According to a first aspect of the present invention, there is provided an n layer made of gallium nitride (GaN) having an n-conduction type and indium gallium nitride (Ga _X1 In _1-X1 N; 0
A light emitting layer made of <X1 <1), a p layer made of aluminum gallium nitride (Al _X2 Ga _1-X2 N; O <X2 <1) directly bonded to the light emitting layer, and a p layer formed on the p layer. It is characterized by having a contact layer made of p-type GaN and an electrode made of nickel (Ni) formed on the contact layer.

[0006] The invention of claim 2 is a group III nitride semiconductor (Al _x
Ga _Y In _1-XY N; 0 ≤X ≤1,0 ≤Y ≤1,0 ≤X + Y ≤1), and an n-layer showing an n-conductivity type and a p-layer showing a p-conductivity type, In a light emitting device having a three-layer structure in which a light emitting layer interposed therebetween is formed by a heterojunction, nickel (N
It is characterized in that it has an electrode composed of i), and a donor impurity and an acceptor impurity are added to the light emitting layer.

According to the invention of claim 3, a group III nitride semiconductor (Al _x
Ga _Y In _1-XY N; 0 ≤X ≤1,0 ≤Y ≤1,0 ≤X + Y ≤1), and an n-layer showing an n-conductivity type and a p-layer showing a p-conductivity type, In a light emitting device having a three-layer structure in which a light emitting layer interposed therebetween is formed by a heterojunction, the light emitting layer is a gallium nitride (G
aN) or aluminum-containing Group III nitride semiconductor (Al _x3 Ga
_Y3 In _1-X3-Y3 N; 0 <X3 ≦ 1,0 ≦ Y3 ≦ 1,0 ≦ X3 + Y3 ≦ 1), and a donor impurity and an acceptor impurity are added. Further, the invention of claim 4 is characterized in that in claim 3, the p-layer has an electrode made of nickel (Ni).

According to a fifth aspect of the present invention, in the second or fourth aspect, the contact layer made of p-GaN is formed between the p layer and the electrode.

[0009]

As described above, since the donor impurity and the acceptor impurity are mixed in the light emitting layer, the light emitting mechanism is the recombination of the electron of the donor level and the hole of the acceptor level, and the light emission. Strength increased. Further, the recombination of the electron of the donor level and the hole of the acceptor level also occurs inside the light emitting layer, and as a result, the emission intensity is improved.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS First Embodiment In FIG. 1, a light emitting diode 10 has a sapphire substrate 1 on which 500.degree.
An N 2 buffer layer 2 is formed. The buffer layer 2
On the top, in order, a film thickness of about 2.0 μm and an electron concentration of 2 × 10 ¹⁸ / c
High carrier concentration n ⁺ layer 3 composed of m ³ silicon-doped GaN, film thickness of about 2.0 μm, electron concentration of 2 × 10 ¹⁸ / cm ³ of silicon-doped (Al _x2 Ga _1-x2 ) _y2 In _1-y2 N A high carrier concentration n ⁺ layer 4, a film thickness of about 0.5 μm, an i-layer (light emitting layer) 5 composed of cadmium (Cd) and silicon-doped (Al _x1 Ga _1-x1 ) _y1 In _1-y1 N, a film thickness of about A p-layer 6 composed of magnesium-doped (Al _x2 Ga _1-x2 ) _y2 In _1-y2 N with a thickness of 1.0 μm and a hole concentration of 2 × 10 ¹⁷ / cm ³ is formed. Then, an electrode 7 made of nickel connected to the p layer 6 and an electrode 8 made of nickel connected to the high carrier concentration n ⁺ layer 4 are formed. The electrode 7 and the electrode 8 are electrically insulated and separated by the groove 9.

Next, a method of manufacturing the light emitting diode 10 having this structure will be described. The light emitting diode 10 includes:
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 carrier gas H ₂ or N ₂ and trimethylgallium (Ga
(CH ₃ ) ₃ ) (hereinafter referred to as “TMG”), trimethylaluminum (Al (CH ₃ ) ₃ ) (hereinafter referred to as “TMA”), and trimethylindium (In (CH ₃ ) ₃ ) (hereinafter referred to as “TMI”). ), Dimethylcadmium (Cd (CH ₃ ) ₂ ) (hereinafter referred to as “DMCd”), silane (SiH ₄ ), and cyclopentadienyl magnesium (Mg
(C ₅ H ₅ ) ₂ ) (hereinafter referred to as “CP ₂ Mg”).

First, a single crystal sapphire substrate 1 having an a-plane as a main surface, which has been cleaned by organic cleaning and heat treatment, is mounted on a susceptor placed in a reaction chamber of a M0VPE apparatus. Next, while flowing H ₂ at normal pressure into the reaction chamber at a flow rate of 2 liter / min, the temperature was 1100
The sapphire substrate 1 was subjected to gas-phase etching at a temperature of ℃.

[0013] Next, by lowering the temperature to 400 ° C., and H ₂
20 liter / min, NH ₃ 10 liter / min, TMA 1.8 × 10 ^-5
Supplying at mol / min, an AlN buffer layer 2 was formed to a thickness of about 500 °. Next, the temperature of the sapphire substrate 1 was set to 1150
℃ to retain a thickness of about 2.2 [mu] m, the electron concentration of 2 × 10 ¹⁸ / cm high carrier concentration of GaN silicon doped ³ n ⁺ layer 3
Was formed.

Hereinafter, the composition ratios of the light emitting layer 5 (active layer) and the cladding layers 4 and 6 and the crystal growth conditions were set when the emission peak wavelength was set to 430 nm with cadmium (Cd) and silicon (Si) as the emission centers. Here is an example. After the formation of the high carrier concentration n ⁺ layer 3, the sapphire substrate 1
Is maintained at 850 ° C., N ₂ or H ₂ is 10 liter / min, NH
₃ for 10 liter / min, TMG for 1.12 × 10 ^-4 mol / min, TMA for
0.47 × 10 ^-4 mol / min, TMI 0.1 × 10 ^-4 mol / min and silane introduced, film thickness about 0.5 μm, concentration 1 × 10 ¹⁸ / c
A high carrier concentration n ⁺ layer 4 made of (Al _0.47 Ga _0.53 ) _0.9 In _0.1 N doped with m ³ silicon was formed.

Subsequently, the temperature was maintained at 850 ° C. and N ₂ or H _{2 was} added.
20 liter / min, NH ₃ 10 liter / min, TMG 1.53 × 10
^-4 mol / min, TMA 0.47 × 10 ^-4 mol / min, TMI 0.02 ×
Introducing 10 ⁻⁴ mol / min, DMCd of 2 × 10 ⁻⁷ mol / min and silane of 10 × 10 ⁻⁹ mol / min, and doping cadmium (Cd) and silicon (Si) with a film thickness of about 0.5 μm. (Al _0.3 Ga _0.7 ) _0.94 In _0.06
A light emitting layer 5 made of N 2 was formed. The light emitting layer 5 is a high resistance layer. The concentration of cadmium (Cd) in the light emitting layer 5 is
5 × 10 ¹⁸ / cm ³ and the concentration of silicon (Si) is 1 × 10 ¹⁸
a / cm ^3.

Subsequently, the temperature is maintained at 1100 ° C. and N ₂ or H ₂
20 liter / min, NH ₃ 10 liter / min, TMG 1.12 × 10
^-4 mol / min, TMA 0.47 × 10 ^-4 mol / min, TMI 0.1 ×
10 ^-4 mol / min, and 2 × 10 ^-4 mol / min of CP ₂ Mg were introduced, and a magnesium (Mg) -doped (Al
_A p-layer 6 made of _0.47 Ga _0.53 ) _0.9 In _0.1 N was formed. p
The magnesium concentration in layer 6 is 1 × 10 ²⁰ / cm ³ . In this state, the p layer 6 is still an insulator having a resistivity of 10 ⁸ Ωcm or more.

Next, the p-type layer 6 was uniformly irradiated with an electron beam by using a reflection electron beam diffractometer. The electron beam irradiation conditions are: accelerating voltage about 10KV, sample current 1μA, beam moving speed 0.2m
m / sec, beam diameter 60 μmφ, vacuum degree 5.0 × 10 ⁻⁵ Torr. Due to this electron beam irradiation, the p-layer 6 has a hole concentration of 2
It became a p-type semiconductor having × 10 ¹⁷ / cm ³ and resistivity of 2Ωcm.
Thus, a wafer having a multilayer structure as shown in FIG. 2 was obtained.

FIGS. 3 to 7 described below are cross-sectional views showing only one element on the wafer. In fact, a wafer in which this element is continuously repeated is processed, and then each of the elements is processed. It is cut for each element.

As shown in FIG. 3, a SiO ₂ layer 11 having a thickness of 2000 Å was formed on the p layer 6 by sputtering.
Next, a photoresist 12 was applied on the SiO ₂ layer 11. Then, by photolithography, an electrode formation site A corresponding to the hole 15 formed to reach the high carrier concentration n ⁺ layer 4 on the p layer 6 and its electrode formation portion are insulated and separated from the electrode of the p layer 6. The photoresist at the portion B where the groove 9 was formed 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 type etching solution. Next, as shown in FIG.
The p layer 6, which is not covered by the photoresist 12 and the SiO ₂ layer 11, and the lower light emitting layer 5 and a part of the upper surface of the high carrier concentration n ⁺ layer 4 are partially vacuumed at a pressure of 0.04 Torr and a high frequency power of 0.
After dry-etching by supplying 44 W / cm ² and BCl ₃ gas at a rate of 10 ml / min, dry-etching was performed with Ar. In this step, a hole 15 for extracting an electrode from the high carrier concentration n ⁺ layer 4 and a groove 9 for insulating and separating were formed.

Next, as shown in FIG. 6, the SiO ₂ layer 11 remaining on the p layer 6 was removed with hydrofluoric acid. Next, as shown in FIG. 7, a Ni layer 13 was formed on the entire surface of the sample by vapor deposition. Thereby, the Ni layer 13 electrically connected to the high carrier concentration n ⁺ layer 4 is formed in the hole 15.
Then, as shown in FIG. 7, a photoresist 14 is applied on the Ni layer 13, and the photoresist 14 is formed into a high carrier concentration n ⁺ layer 4 and p by photolithography.
A pattern was formed into a predetermined shape so that the electrode portion for the layer 6 remained.

Next, as shown in FIG. 7, the exposed portion of the lower Ni layer 13 was etched with a nitric acid-based etching solution using the photoresist 14 as a mask. At this time, the Ni layer 13 deposited on the groove 9 for insulation separation is completely removed.
Next, the photoresist 14 was removed with acetone, leaving the electrode 8 of the high carrier concentration n ⁺ layer 4 and the electrode 7 of the p layer 6. Thereafter, the wafer processed as described above was cut into individual devices to obtain a gallium nitride-based light emitting device having a pn structure shown in FIG.

The light emitting device thus obtained had a driving current of 20 mA, an emission peak wavelength of 430 nm and an emission intensity of 100 mcd.

Also, the above-mentioned cadmium (Cd) and silicon (Si)
It is preferable that the concentration of each of the above is in the range of 1 × 10 ¹⁷ to 1 × 10 ²⁰ in order to improve the emission intensity. Also, silicon (Si)
It is more desirable that the concentration of γ is smaller than that of cadmium (Cd) by about 1/2 to 1/10.

In the above embodiment, the p layer 6 and the high carrier concentration n ⁺ layer 4 in which the band gap of the light emitting layer 5 exists on both sides.
Is formed in a double heterojunction that is smaller than the band gap. Also, Al, G of these three layers
The component ratios of a and In are selected so as to match the lattice constant of the high carrier concentration n ⁺ layer of GaN. Further, although the double heterojunction structure is used in the above embodiment, a single heterojunction structure may be used.

Second Embodiment The light emitting layer 5 of the first embodiment is composed of cadmium (Cd) and silicon (S
i) is added, but the light emitting layer 5 of the second embodiment is added with zinc (Zn) and silicon (Si) as shown in FIG. After forming the above high carrier concentration n ⁺ layer 3,
Then, the temperature of the sapphire substrate 1 was maintained at 800 ° C., and N ₂
20 liter / min, NH ₃ 10 liter / min, TMG 1.12 × 10
^-4 mol / min, TMA 0.47 × 10 ^-4 mol / min, TMI 0.1 ×
Introducing 10 ^-4 mol / min and silane, film thickness of about 0.5 μ
m, concentration 2 × 10 ¹⁹ / cm ³ of silicon-doped (Al _0.3 Ga _0.7 ).
_A high carrier concentration n ⁺ layer 4 composed of _0.94 In _0.06 N was formed.

Then, the temperature was maintained at 1150 ° C. and 20 l of N ₂ was added.
iter / min, the NH ₃ 10liter / min, 1.53 × 10 ^-4 mol / min TMG, 0.47 × 10 ^-4 mol / min TMA, 0.02 × 10 ^-4 mol / min TMI, silane 10 × 10 ^{- 9} mol / min, DEZ was introduced at 2 × 10 ^-4 mol / min for 7 min, and silicon (Si) and zinc (Zn) -doped (Al _0.09 Ga _0.91 ) _0.99 In _0.01 N with a film thickness of about 0.5 μm were introduced. Was formed. Zinc in this light emitting layer 5
The concentration of (Zn) is 2 × 10 ¹⁸ / cm ³ , and the concentration of silicon (Si) is 1 × 10 ¹⁸ / cm ³ .

Subsequently, the temperature was maintained at 1100 ° C. and 20 L of N ₂ was added.
iter / min, the NH ₃ 10liter / min, 1.12 × 10 ^-4 mol / min TMG, 0.47 × 10 ^-4 mol / min TMA, 0.1 × 10 ^-4 mol / min TMI, and the CP ₂ Mg 2 × 10 ^-4 mol / min introduced, magnesium (Mg) doped (Al _0.3 Ga _0.7 ) with a film thickness of about 1.0 μm
_A p-layer 6 of _0.94 In _0.06 N was formed. The magnesium concentration in the p layer 6 is 1 × 10 ²⁰ / cm ³ . In this state,
The p-layer 6 is still an insulator having a resistivity of 10 ⁸ Ωcm or more.

Next, the p-type layer 6 was uniformly irradiated with an electron beam using a reflection electron diffraction apparatus. The irradiation conditions of the electron beam are the same as in the first embodiment. Hereinafter, the light emitting diode 10 was formed by the same manufacturing method as in the first embodiment. The emission peak wavelength of the light emitting diode 10 is 430 nm, and the emission intensity is 1000 mcd.

The light emitting diode of the third embodiment The third embodiment is as shown in FIG. 9,
Magnesium is used for the light emitting layer 5 of the light emitting diode of the second embodiment.
(Mg) is further added and irradiated with an electron beam to form a p-type. The formation of the layers other than the light emitting layer 5 is the same as in the second embodiment. Further, the light emitting layer 5 is different only in that CP ₂ Mg is further added at a rate of 2 × 10 ⁻⁷ mol / min in the manufacturing process of the light emitting diode of the second embodiment.

Magnesium (Mg) and zinc having a film thickness of about 0.5 μm
(Zn) and silicon (Si) doped (Al _0.09 Ga _0.91 ) _0.99
The light emitting layer 5 of In _0.01 N was formed. The light emitting layer 5 is still an insulator having a resistivity of 10 ⁸ Ωcm or more in this state. The concentration of magnesium (Mg) in the light emitting layer 5 is 1 × 10 ¹⁹ / cm ³
And the concentration of zinc (Zn) is 2 × 10 ¹⁸ / cm ³ and the concentration of silicon (Si) is 1 × 10 ¹⁸ / cm ³ .

Then, the reflection electron beam diffractometer is used to uniformly irradiate the light emitting layer 5 and the p layer 6 with an electron beam. The electron beam irradiation conditions are the same as in the first embodiment. This electron beam irradiation causes the light emitting layer 5 and the p layer 6 to have a hole concentration of 2 × 10 ¹⁷ / c.
It became a p-conducting semiconductor with m ³ and a resistivity of 2 Ωcm.

The light emitting diode of the fourth embodiment The fourth embodiment is obtained by the light-emitting layer 5 GaN, a single heterojunction. That is, one junction is the GaN high-concentration n ⁺ layer 4 to which silicon (Si) is added at a high concentration and the GaN light-emitting layer 5 to which zinc (Zn) and silicon (Si) are added. The junction is made of a GaN light emitting layer 5 and a p-type Al _0.1 Ga _0.9 N p-doped with magnesium (Mg).
It is a bond with the layer 61. In this embodiment, a contact layer 62 made of p-conductivity type GaN doped with magnesium (Mg) is formed on the p layer 61. Further, the trench 9 for insulation separation is formed so as to penetrate the contact layer 62, the p layer 61, and the light emitting layer 5.

In FIG. 10, the light emitting diode 10 is
A sapphire substrate 1 is provided.
An AlN buffer layer 2 of 500 Å is formed thereon. On the buffer layer 2, a high carrier concentration n ⁺ layer 4 made of silicon-doped GaN having an electron concentration of 2 × 10 ¹⁸ / cm ³ and a film thickness of approximately 0.5 μm, zinc and silicon-doped layer are sequentially formed on the buffer layer 2. Light emitting layer 5 made of GaN, film thickness of about 0.5 μm, and hole concentration of 2 × 10 ¹⁷ / cm ³ magnesium-doped Al _0.1 Ga _0.9 N
P-layer 61 consisting of, film thickness about 0.5 μm, hole concentration 2 × 10
^A contact layer 62 made of magnesium-doped GaN of ¹⁷ / cm ³ is formed. Then, an electrode 7 made of nickel connected to the contact layer 62 and an electrode 8 made of nickel connected to the high carrier concentration n ⁺ layer 4 are formed. The electrode 7 and the electrode 8 are electrically insulated and separated by the groove 9.

Next, a method of manufacturing the light emitting diode 10 having this structure will be described. As in the first embodiment, the process is performed up to the AlN buffer layer 2. Next, the temperature of the sapphire substrate 1 was maintained at 1150 ° C., the film thickness was about 4.0 μm, and the electron concentration was 2 ×
A high carrier concentration n ⁺ layer 4 made of GaN doped with silicon at 10 ¹⁸ / cm ³ was formed.

Hereinafter, the composition ratios of the light emitting layer 5, the cladding layer, that is, the p layer 61, and the contact layer 62 and the crystal growth conditions when the emission peak wavelength is set to 430 nm with zinc (Zn) and silicon (Si) as the emission centers. An example will be described. After forming the above-mentioned high carrier concentration n ⁺ layer 4, the sapphire substrate 1 is continuously formed.
Temperature of 1000 ℃, N ₂ or H ₂ 20 liter / min, NH
₃ for 10 liter / min, TMG for 1.53 × 10 ^-4 mol / min, DMZ for
2 × 10 ^-7 mol / min, silane was introduced at 10 × 10 ^-9 mol / min, and a film thickness of about 0.5 μm zinc (Zn) and silicon (Si) was doped.
A light emitting layer 5 of GaN was formed.

Subsequently, the temperature was maintained at 1000 ° C. and N ₂ or H _{2 was} added.
20 liter / min, NH ₃ 10 liter / min, TMG 1.12 × 10
^-4 mol / min, 0.47 × 10 ^-4 mol / min of TMA and CP ₂ Mg
^Is introduced at a ^rate of 2 × 10 ⁻⁷ mol / min for 7 minutes to form a p-layer of magnesium (Mg) doped Al _0.1 Ga _0.9 N having a thickness of about 0.5 μm.
Layer 61 was formed. The p layer 61 still has a resistivity of 10
It is an insulator of ⁸ Ωcm or more. The concentration of magnesium (Mg) in p layer 61 is 1 × 10 ¹⁹ / cm ³ .

Subsequently, the temperature was maintained at 1000 ° C. and N ₂ or H _{2 was} added.
20 liter / min, NH ₃ 10 liter / min, TMG 1.12 × 10
^-4 mol / min, and 2 × 10 ^-4 mol / min of CP ₂ Mg,
A contact layer 62 made of GaN doped with magnesium (Mg) and having a film thickness of about 0.5 μm was formed. The magnesium concentration of the contact layer 62 is 1 × 10 ²⁰ / cm ³ . In this state, the contact layer 62 is still an insulator having a resistivity of 10 ⁸ Ωcm or more.

Next, the p-layer 61 and the contact layer 62 were uniformly irradiated with an electron beam by using a reflection electron beam diffractometer.
The irradiation conditions of the electron beam are the same as in the first embodiment. By the irradiation of this electron beam, the p layer 61 and the contact layer 62 are
It became a p-conduction type semiconductor with a hole concentration of 2 × 10 ¹⁷ / cm ³ and a resistivity of 2 Ωcm.

As described above, the light emitting diode 10 in which the light emitting layer 5 is doped with the acceptor of zinc (Zn) and the donor of silicon (Si) in the single heterojunction was manufactured. In the fourth embodiment, the light emitting layer 5 may be doped with magnesium (Mg) and irradiated with an electron beam to make the light emitting layer 5 a p-conduction type.

Fifth Embodiment Different from the fourth embodiment, as shown in FIG. 11, the light emitting layer 5 is made of Al _x2 Ga in which zinc (Zn) and silicon (Si) are simultaneously doped.
_1-x2 N, p-layer 61 is magnesium (Mg) -doped Al
_{The x1} Ga _1-x1 N, high carrier concentration n ⁺ layer 4 is formed of Al _x3 Ga _1-x3 N doped with silicon (Si). And
The composition ratios x1, x2, x3 are set so that the band gap of the light emitting layer 5 becomes smaller than the band gaps of the high carrier concentration n ⁺ layer 4 and the p layer 61 so that a double hetero junction or a single hetero junction is formed. It Carriers are confined in the light emitting layer 5 by the double heterojunction and the single heterojunction, and the emission brightness is improved. The light emitting layer 5 may be semi-insulating, p-conductive type, or n-conductive type.

The light emitting diode of the sixth embodiment The sixth embodiment is different from the light emitting diode of the fifth embodiment, as shown in FIG. 12, the zinc in the light emitting layer 5 (Zn) and silicon (Si) is doped at the same time Ga _y In _1-y N
, P layer 61 is Al _x1 Ga doped with magnesium (Mg)
_{The 1-x1} N, high carrier concentration n ⁺ layer 4 may be formed of Al _x2 Ga _1-x2 N doped with silicon (Si). And the composition ratio
x1, y, x2 are set so that a double heterojunction is formed in which the bandgap of the light emitting layer 5 becomes smaller than the bandgap of the high carrier concentration n ⁺ layer 4 and the p layer 61.
Light emitting layer 5 by double heterojunction and single heterojunction
The carriers are confined in the light emission, and the emission brightness is improved. The light emitting layer 5 may be semi-insulating, p-conductive type, or n-conductive type.

In FIG. 13, the light emitting diode 10 is
A sapphire substrate 1 is provided.
An AlN buffer layer 2 of 500 Å is formed thereon. On the buffer layer 2, a high carrier concentration n ⁺ layer 4 made of silicon-doped GaN having an electron concentration of 2 × 10 ¹⁸ / cm ³ and a film thickness of approximately 0.5 μm, zinc and silicon-doped layer are sequentially formed on the buffer layer 2. Ga _0.94 In _0.06 N of light emitting layer 5, film thickness about 0.5 μ
m, hole concentration 2 × 10 ¹⁷ / cm ³ magnesium-doped Al
_A p-layer 61 made of _0.1 Ga _0.9 N and a contact layer 62 made of magnesium-doped GaN having a hole concentration of 2 × 10 ¹⁷ / cm ³ and having a film thickness of about 0.5 μm are formed. Then, an electrode 7 made of nickel connected to the contact layer 62 and an electrode 8 made of nickel connected to the high carrier concentration n ⁺ layer 4 are formed. The electrode 7 and the electrode 8 are electrically insulated and separated by the groove 9.

Next, a method of manufacturing the light emitting diode 10 having this structure will be described. As in the first embodiment, the process is performed up to the AlN buffer layer 2. Next, the temperature of the sapphire substrate 1 was maintained at 1150 ° C., the film thickness was about 4.0 μm, and the electron concentration was 2 ×
A high carrier concentration n ⁺ layer 4 made of GaN doped with silicon at 10 ¹⁸ / cm ³ was formed.

Hereinafter, the composition ratios of the light emitting layer 5, the cladding layer, that is, the p layer 61, and the contact layer 62 and the crystal growth conditions when the emission peak wavelength was set to 450 nm with zinc (Zn) and silicon (Si) as the emission centers. An example will be described. After forming the above-mentioned high carrier concentration n ⁺ layer 4, the sapphire substrate 1 is continuously formed.
Temperature of 850 ℃, N ₂ or H ₂ 20 liter / min, NH
₃ for 10 liter / min, TMG for 1.53 × 10 ^-4 mol / min, TMI for
0.02 × 10 ^-4 mol / min, DMZ at 2 × 10 ^-7 mol / min, and silane at 10 × 10 ^-9 mol / min were introduced.
n) and a silicon (Si) -doped Ga _0.94 In _0.06 N light emitting layer 5 were formed.

Subsequently, the temperature was maintained at 850 ° C. and N ₂ or H _{2 was} added.
20 liter / min, NH ₃ 10 liter / min, TMG 1.12 × 10
^-4 mol / min, 0.47 × 10 ^-4 mol / min of TMA and CP ₂ Mg
^Is introduced at a ^rate of 2 × 10 ⁻⁷ mol / min for 7 minutes to form a p-layer of magnesium (Mg) doped Al _0.1 Ga _0.9 N having a thickness of about 0.5 μm.
Layer 61 was formed. The p layer 61 still has a resistivity of 10
It is an insulator of ⁸ Ωcm or more. The concentration of magnesium (Mg) in p layer 61 is 1 × 10 ¹⁹ / cm ³ .

Subsequently, the temperature was maintained at 850 ° C. and N ₂ or H _{2 was} added.
20 liter / min, NH ₃ 10 liter / min, TMG 1.12 × 10
^-4 mol / min, and 2 × 10 ^-4 mol / min of CP ₂ Mg,
A contact layer 62 made of GaN doped with magnesium (Mg) and having a film thickness of about 0.5 μm was formed. The magnesium concentration of the contact layer 62 is 1 × 10 ²⁰ / cm ³ . In this state, the contact layer 62 is still an insulator having a resistivity of 10 ⁸ Ωcm or more.

Next, the p-layer 61 and the contact layer 62 were uniformly irradiated with an electron beam by using a reflection electron beam diffractometer.
The irradiation conditions of the electron beam are the same as in the first embodiment. By the irradiation of this electron beam, the p layer 61 and the contact layer 62 are
It became a p-conduction type semiconductor with a hole concentration of 2 × 10 ¹⁷ / cm ³ and a resistivity of 2 Ωcm.

In the above first to sixth embodiments, the light emitting layer 5 may be semi-insulating, p-conducting or n-conducting.
Further, it has been found that the above-mentioned concentrations of zinc (Zn) and silicon (Si) are preferably in the range of 1 × 10 ¹⁷ to 1 × 10 ²⁰ to improve the emission intensity. More preferably 1
A range of × 10 ¹⁸ to 1 × 10 ¹⁹ is preferable. If it is less than 1 × 10 ¹⁸ , the effect is small, and if it is more than 1 × 10 ¹⁹ , the crystallinity becomes poor.
The concentration of silicon (Si) is 10 times higher than that of zinc (Zn).
It is preferably 1/10, more preferably about 1 to 1/10 or less.

The light emitting layer 5 is i-type (semi-insulating) if the concentration of silicon (Si) is higher than the concentration of cadmium (Cd), and n if the concentration of silicon (Si) is lower than the concentration of cadmium (Cd).
Conductive type.

Further, in the above-mentioned embodiment, an example in which cadmium (Cd) is used as the acceptor impurity and silicon (Si) is used as the donor impurity is shown. However, the acceptor impurity is beryllium (Be),
Magnesium (Mg), Zinc (Zn), Cadmium (Cd), Mercury (H
g) may be used. In addition, donor impurities include carbon
(C), Silicon (Si), Germanium (Ge), Tin (Sn), Lead (P)
b) can be used.

Further, sulfur (S) is used as a donor impurity.
, Selenium (Se) and tellurium (Te) can also be used. p
Molding can be performed by electron beam irradiation, thermal annealing, heat treatment in N ₂ plasma gas, or laser irradiation.

[Brief description of drawings]

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

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

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

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

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

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

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

FIG. 8 is a configuration diagram showing a configuration of a light emitting diode according to a second embodiment.

FIG. 9 is a configuration diagram showing a configuration of a light emitting diode according to a third embodiment.

FIG. 10 is a configuration diagram showing a configuration of a light emitting diode according to a fourth embodiment.

FIG. 11 is a configuration diagram showing a configuration of a light emitting diode according to a fifth embodiment.

FIG. 12 is a configuration diagram showing a configuration of a light emitting diode according to a sixth embodiment.

FIG. 13 is a configuration diagram showing a configuration of a light emitting diode according to a sixth embodiment.

[Explanation of symbols]

10 ... Light-emitting diode 1 ... Sapphire substrate 2 ... Buffer layer 3 ... High carrier concentration n ⁺ layer 4 ... High carrier concentration n ⁺ layer 5 ... Light emitting layer 6 ... P layer 61 ... P layer 62 ... Cap layer 7, 8 ... Electrode 9 …groove

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Naoki Shibata No. 1 Nagahata Ochiai, Kasuga-cho, Nishikasugai-gun, Aichi Toyoda Gosei Co., Ltd. Within Toyoda Gosei Co., Ltd. (72) Inventor, Dosei Sasa, Ochiai, Nagachi, Kasuga-cho, Nishikasugai-gun, Aichi Prefecture Within Toyoda Gosei Co., Ltd. Incorporated (72) Inventor Shiro Yamazaki, Kasuga-cho, Nishi-Kasugai-gun, Aichi Ochiai, Nagachibata No. 1, Otaigai Toyoda Gosei Co., Ltd.

Claims (5)

[Claims] 1. A light emitting layer comprising an n-type layer of gallium nitride (GaN) exhibiting an n-conduction type and indium gallium nitride (Ga _X1 In _1-X1 N; 0 <X1 <1) directly bonded to the n _- layer. And aluminum gallium nitride (Al
_X2 Ga _1-X2 N; O <X2 <1) p-layer, p-type GaN contact layer formed on the p-layer, and nickel (Ni) formed on the contact layer A group III nitride semiconductor light-emitting device, comprising: an electrode. 2. A group III nitride semiconductor (Al _x Ga _Y In _1-XY N; 0 ≤
X ≦ 1,0 ≦ Y ≦ 1,0 ≦ X + Y ≦ 1), the n layer showing the n-conductivity type, the p layer showing the p-conductivity type, and the light-emitting layer interposed therebetween are heterojunctions. The formed light emitting device having a three-layer structure has an electrode made of nickel (Ni) for the p-layer, and a donor impurity and an acceptor impurity are added to the light-emitting layer. Group nitride semiconductor light emitting device. 3. Group III nitride semiconductor (Al _x Ga _Y In _1-XY N; 0 ≤
X ≦ 1,0 ≦ Y ≦ 1,0 ≦ X + Y ≦ 1), the n layer showing the n-conductivity type, the p layer showing the p-conductivity type, and the light-emitting layer interposed therebetween are heterojunctions. In the light emitting device having a formed three-layer structure, the light emitting layer is a Group 3 nitride semiconductor (Al _x3 Ga _Y3 In _1-X3-Y3 N; 0 <X3 ≦ 1,0) containing gallium nitride (GaN) or aluminum. ≤
A group III nitride semiconductor light emitting device, characterized in that Y3 ≦ 1,0 ≦ X3 + Y3 ≦ 1) and that a donor impurity and an acceptor impurity are added. 4. The electrode according to claim 3, further comprising an electrode made of nickel (Ni) for the p layer.
Group nitride semiconductor light emitting device. 5. The Group III nitride semiconductor light emitting device according to claim 2, wherein a contact layer made of p-GaN is formed between the p layer and the electrode.