JP3494841B2 - Group III nitride semiconductor light emitting device - Google Patents

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.
Those using N-based compound semiconductors are known. Since the compound semiconductor is a direct transition type, it has been noted that it has high emission efficiency, and that blue, which is one of the three primary colors of light, is used as the emission color.

Recently, it has been revealed that also in an AlGaInN-based semiconductor, Mg can be doped to irradiate it with an electron beam or can be made into a p-type 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]

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention
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]

[0006]

According to the invention of claim 1, a group III nitride semiconductor (Al _X1 Ga _Y1 In _1-X1-Y1 N; 0 ≤
X1 ≦ 1,0 ≦ Y1 ≦ 1, 0 ≦ X1 + Y1 ≦ 1 and n layer formed of a), group III nitride semiconductor exhibiting p-conduction type _{(Al X2 Ga Y2 In 1-} X2-Y2 N; 0 ≦
X2 ≤ 1, 0 ≤ Y2 ≤ 1, 0 ≤ X2 + Y2 ≤ 1) and a p-layer composed of a group III nitride semiconductor (Al _X3 Ga _Y3 In _1-X3-Y3 N; 0).
≦ X3 ≦ 1, 0 ≦ Y3 ≦ 1, 0 ≦ X3 + Y3 ≦ 1) In a light emitting device having a three-layer structure in which a light emitting layer composed of a heterojunction is formed, an electrode made of nickel (Ni) for the p layer is provided. The light-emitting layer has a donor impurity and an acceptor impurity added thereto.

[0007] The invention of claim 2 is a group 3 exhibiting n-conductivity type
Nitride semiconductor (Al _X1 Ga _Y1 In _1-X1-Y1 N; 0 ≤ X1 ≤ 1, 0 ≤ Y1 ≤
N layer consisting of 1, 0 ≤ X1 + Y1 ≤ 1) and a group 3 showing p conductivity type
Nitride semiconductor (Al _X2 Ga _Y2 In _1-X2-Y2 N; 0 ≤ X2 ≤ 1, 0 ≤ Y2 ≤
P layer consisting of 1, 0 ≤ X2 + Y2 ≤ 1) and 3 interposed therebetween
Group Nitride Semiconductor (Al _X3 Ga _Y3 In _1-X3-Y3 N; 0 ≤ X3 ≤ 1, 0 ≤ Y3
≦ 1, 0 ≦ X3 + Y3 ≦ 1) a light emitting layer in the light-emitting device having a three-layer structure formed by heterojunction light emitting layer group III nitride semiconductor containing gallium nitride (GaN) or aluminum (Al _x3 Ga _Y3 In _1-X3-Y3 N; 0 <X3 ≦ 1, 0 ≦ Y3 ≦ 1, 0 ≦ X3 +
Y3 ≤ 1), to which donor impurities and acceptor impurities are added, and an electrode made of nickel (Ni) for the p layer is provided.

According to a third aspect of the present invention, in the first and second aspects, a 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]

EXAMPLES First Example In FIG. 1, a light emitting diode 10 has a sapphire substrate 1, and 500 Å Al on the sapphire substrate 1.
An N 2 buffer layer 2 is formed. Its buffer layer 2
On the top, in order, a film thickness of about 2.0 μm, electron concentration 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 is
It was manufactured by vapor phase epitaxy by an organometallic compound vapor phase epitaxy method (hereinafter referred to as "M0VPE"). The gas used is NH
₃ and carrier gas H ₂ or N ₂ and trimethylgallium (Ga
(CH _{3) 3)} and (hereinafter referred to as "TMG") and trimethylaluminum (Al (CH _{3) 3)} (hereinafter referred to as "TMA") and trimethyl indium (an In (CH _{3) 3)} (hereinafter "TMI" Dimethyl cadmium (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. Then, at a pressure of 1100 while flowing H ₂ into the reaction chamber at a flow rate of 2 liter / min under normal pressure.
The sapphire substrate 1 was vapor-phase etched at 0 ° C.

Next, the temperature is lowered to 400 ° C. and H ₂ is added.
20 liter / min, NH ₃ 10 liter / min, TMA 1.8 × 10 ^-5
The buffer layer 2 of AlN was formed at a thickness of about 500Å by supplying at a mol / min. Next, the temperature of the sapphire substrate 1 is 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 forming the above-mentioned high carrier concentration n ⁺ layer 3, the sapphire substrate 1 is subsequently formed.
Temperature of 850 ℃, N ₂ or H ₂ 10 liter / min, NH
₃ for 10 liter / min, TMG for 1.12 x 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 of m ³ silicon-doped (Al _0.47 Ga _0.53 ) _0.9 In _0.1 N 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
/ cm ³ .

Subsequently, the temperature was maintained at 1100 ° C. and N ₂ or H _{2 was} added.
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, CP to ₂ Mg 2 × 10 ^-4 mol / min was introduced, a film thickness of about 1.0 [mu] m of 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, and vacuum degree 5.0 × 10 ⁻⁵ Torr. Due to this electron beam irradiation, the p-layer 6 has a hole concentration of 2
× 10 ¹⁷ / cm ^3, was a p conductivity type semiconductor resistivity 2Omucm.
In this way, 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, on the p layer 6, the electrode forming portion A corresponding to the hole 15 formed to reach the high carrier concentration n ⁺ layer 4 and the electrode forming portion are insulated and separated from the electrode of the p layer 6. The photoresist in the portion B where the groove 9 is 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.
Part of the upper surface of the p layer 6 and the light emitting layer 5 thereunder, which is not covered with the photoresist 12 and the SiO ₂ layer 11, and the high carrier concentration n ⁺ layer 4, a vacuum degree of 0.04 Torr and a high frequency power of 0.
44 W / cm ² and BCl ₃ gas were supplied at a rate of 10 ml / min to perform dry etching, and then dry etching was performed using Ar. In this step, a hole 15 for taking out an electrode and a groove 9 for insulating separation were formed for the high carrier concentration n ⁺ layer 4.

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. As a result, 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 in the groove 9 for insulation separation is completely removed.
Next, the photoresist 14 was removed with acetone, and the electrode 8 of the high carrier concentration n ⁺ layer 4 and the electrode 7 of the p layer 6 were left. Then, the wafer treated as described above was cut into each element to obtain a pn structure gallium nitride-based light emitting element 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 from the viewpoint of improving 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, these three layers of Al and G
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, 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 CP ₂ Mg Introduced at 2 × 10 ^-4 mol / min, magnesium (Mg) -doped (Al _0.3 Ga _0.7 ) with a film thickness of about 1.0 μm
_A p-layer 6 made of _0.94 In _0.06 N was formed. The concentration of magnesium 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 electron beam irradiation conditions 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
A light emitting layer 5 made 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
It has a sapphire substrate 1, and the sapphire substrate 1
A 500 Å AlN buffer layer 2 is formed on top. 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. Similar to the first embodiment, the buffer layer 2 of AlN is formed. Next, the temperature of the sapphire substrate 1 is maintained at 1150 ° C., the film thickness is about 4.0 μm, and the electron concentration is 2 ×.
A high carrier concentration n ⁺ layer 4 of 10 ¹⁸ / cm ³ of silicon-doped GaN 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, TMA 0.47 × 10 ^-4 mol / min, and CP ₂ Mg
^Was introduced at 2 × 10 ⁻⁷ mol / min for 7 minutes, and p was made of Al _0.1 Ga _0.9 N doped with magnesium (Mg) and having a thickness of about 0.5 μm.
Layer 61 was formed. The p-layer 61 still has a resistivity of 10 in this state.
It is an insulator of ⁸ Ωcm or more. The concentration of magnesium (Mg) in the 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 CP ₂ Mg introduced at 2 × 10 ^-4 mol / min,
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 electron beam irradiation conditions 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 Unlike 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
It has a sapphire substrate 1, and the sapphire substrate 1
A 500 Å AlN buffer layer 2 is formed on top. 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. Similar to the first embodiment, the buffer layer 2 of AlN is formed. Next, the temperature of the sapphire substrate 1 is maintained at 1150 ° C., the film thickness is about 4.0 μm, and the electron concentration is 2 ×.
A high carrier concentration n ⁺ layer 4 of 10 ¹⁸ / cm ³ of silicon-doped GaN 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, TMA 0.47 × 10 ^-4 mol / min, and CP ₂ Mg
^Was introduced at 2 × 10 ⁻⁷ mol / min for 7 minutes, and p was made of Al _0.1 Ga _0.9 N doped with magnesium (Mg) and having a thickness of about 0.5 μm.
Layer 61 was formed. The p-layer 61 still has a resistivity of 10 in this state.
It is an insulator of ⁸ Ωcm or more. The concentration of magnesium (Mg) in the 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 CP ₂ Mg introduced at 2 × 10 ^-4 mol / min,
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 electron beam irradiation conditions 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 deteriorates.
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 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 embodiment.

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

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

FIG. 6 is a cross-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 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 layers 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. Toyoda Gosei Co., Ltd. (72) Inventor Sasa Dosei Aichi Nagashiro, Kasuga-cho, Aichi Prefecture Ochiai, Nagahata No. 1 Toyoda Gosei Co., Ltd. Incorporated (72) Inventor Shiro Yamazaki, Kasuga-cho, Nishi-Kasugai, Aichi 1 Ochiai, Nagahata, Toyoda Gosei Co., Ltd. (56) Reference JP 5-291621 (JP, A) JP 4-242985 ( JP, A) JP-A-4-10665 (JP, A) JP-A-2-264483 (JP, A) JP-A-6-260680 (JP, A) Appl. Phys. Lett. Vol. 64 No. 13 (1994) p1687-1689 Jpn. J. Appl. Phys. Part 2 Vol. 32 No. 1A / B (1993) p. L8-L11 (58) Fields investigated (Int.Cl. ⁷ , DB name) H01L 33/00 H01S 5/00-5/50

Claims (3)

(57) [Claims] 1. An n-conductivity type is shown.Group 3 nitride semiconductor (Al _X1 G
a _Y1 In _1-X1-Y1 N; 0 ≤ X1 ≤ Ten ≤ Y1 ≤ Ten ≤ X1 + Y1 ≤ 1) Or
Consists ofShows n-layer and p-conduction typeGroup 3 nitride semiconductor (Al _X2 G
a _Y2 In _1-X2-Y2 N; 0 ≤ X2 ≤ Ten ≤ Y2 ≤ Ten ≤ X2 + Y2 ≤ 1) Or
Consists ofp layer and intervening betweenGroup 3 nitride semiconductor (Al
_X3 Ga _Y3 In _1-X3-Y3 N; 0 ≤ X3 ≤ Ten ≤ Y3 ≤ Ten ≤ X3 + Y3 ≤
1) Consisting ofA three-layer structure in which the light emitting layer is formed by a heterojunction
In the light emitting element having An electrode made of nickel (Ni) for the p-layer, The light emitting layer contains donor impurities and acceptor impurities.
Group III nitride semiconductor light emission characterized by being added
element. 2. An n-conductivity type is shown.Group 3 nitride semiconductor (Al _X1 G
a _Y1 In _1-X1-Y1 N; 0 ≤ X1 ≤ Ten ≤ Y1 ≤ Ten ≤ X1 + Y1 ≤ 1) Or
Consists ofShows n-layer and p-conduction typeGroup 3 nitride semiconductor (Al _X2 G
a _Y2 In _1-X2-Y2 N; 0 ≤ X2 ≤ Ten ≤ Y2 ≤ Ten ≤ X2 + Y2 ≤ 1) Or
Consists ofp layer and intervening betweenGroup 3 nitride semiconductor (Al
_X3 Ga _Y3 In _1-X3-Y3 N; 0 ≤ X3 ≤ Ten ≤ Y3 ≤ Ten ≤ X3 + Y3 ≤
1) Consisting ofA three-layer structure in which the light emitting layer is formed by a heterojunction
In the light emitting element having The light emitting layer contains gallium nitride (GaN) or aluminum.
Group 3 nitride semiconductors (Al_x3Ga_Y3In_1-X3-Y3N; 0 <X3 ≦ 1, 0
≤Y3 ≤ 1, 0 ≤ X3 + Y3 ≤ 1)
Septa impurities and added, Having an electrode made of nickel (Ni) for the p-layer
A group III nitride semiconductor light emitting device, comprising: 3. A group III nitride semiconductor light-emitting device according to claim 1 or claim 2, characterized in that the contact layer made of p-GaN is formed between the electrode and the p layer.