JP3792003B2 - Semiconductor light emitting device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a semiconductor light emitting device made of a III-V group compound containing nitrogen (N) in an active layer and a cladding layer.
[0002]
[Prior art]
In recent years, as a key device for next-generation high-density information processing technology, a III-V group compound semiconductor containing nitrogen that enables a shorter wavelength of a laser has attracted attention. In the semiconductor light emitting device using the group III-V compound semiconductor containing nitrogen, there is an extremely strong demand for a reduction in operating voltage.
[0003]
A conventional semiconductor light emitting device made of a group III-V compound semiconductor containing nitrogen will be described below with reference to the drawings.
[0004]
FIG. 10 is a sectional view showing a laser element or light emitting diode element made of a III-V group compound semiconductor containing nitrogen as a first conventional example. As shown in FIG. 10, on a substrate 101 made of sapphire having a plane orientation of (0001), a buffer layer 102 made of GaN, and an n-type GaN layer 103 having a stepped portion on the upper side of the buffer layer 102. Are sequentially formed.
[0005]
On the upper side of the stepped portion on the n-type GaN layer 103, n-type Ga_0.95In_0.05N layer 104 and n-type Al_0.05Ga_0.95N-type cladding layer 105 made of N, n-type guide layer 106 made of n-type GaN, and undoped Ga_0.95In_0.05Barrier layer 107a made of N and undoped Ga_0.8 In_0.2A multi-quantum well layer 107 in which active layers 107b made of N layers are alternately stacked in quadruple, and p-type Al_0.2 Ga_0.8 N layer 108, p type guide layer 109 made of p type GaN, p type Al_0.1 Ga_0.9 A p-type cladding layer 110 made of N, a contact layer 111 made of p-type GaN, and a positive electrode 112 in which Ni and Au are stacked are sequentially formed.
[0006]
On the lower side of the stepped portion on the n-type GaN layer 103, a negative electrode 113 formed by stacking Ti and Al is formed.
[0007]
The semiconductor light emitting device shown in FIG. 10 is characterized in that the cavity length is 700 μm, the stripe width is 2 μm, and the active layer 107b has a double heterostructure having a multiple quantum well structure. With this double heterostructure, the oscillation wavelength is 408 nm, the threshold voltage is 8 V, the threshold current is 130 mA, and the threshold current density is 9 kA / cm.² And continuous oscillation at room temperature with a lifetime of 1 second (Shuji Nakamura et al .; Applied Physics Letters Vol. 69 (1996) pp.4056-4058).
[0008]
Furthermore, as a second conventional example, Japanese Patent Laid-Open No. 8-97468 discloses Ga-doped p-type in the contact layer 111 in a III-V group compound semiconductor containing nitrogen._1-x In_x It is shown that the Schottky barrier generated between the positive electrode 112 and the contact layer 111 can be reduced by using N (where x is a real number of 0 <x <1 and the same shall apply hereinafter). .
[0009]
[Problems to be solved by the invention]
However, the first conventional example has a problem that the reduction of the operating voltage is not realized. Also. The second conventional example has a problem that although the operating voltage is reduced, a p-type contact layer having a sufficient film thickness cannot be formed.
[0010]
The first object of the present invention is to solve the above-mentioned conventional problems and to obtain a great satisfaction in reducing the operating voltage of the semiconductor light emitting device, and to reduce the operating voltage and form a p-type contact layer. A second object is to achieve both.
[0011]
[Means for Solving the Problems]
As a result of various studies for reducing the operating voltage, the present inventors have found that there is a gap between the p-type contact layer made of GaN doped with a p-type impurity and the positive electrode Ni in contact with the contact layer 111. It has been found that since the Schottky barrier is large, the contact resistance between the p-type contact layer and the metallic Ni increases, and the operating voltage as a light emitting element increases. This is not a study on semiconductor light-emitting devices, but Hidenori Ishikawa et al. “The 56th Annual Meeting of the Japan Society of Applied Physics 27p-ZE-17 (1995, Preliminary Proceedings Vol.1 p.247) And W. W. et al. A. Supported by Harrison, Tadanobu Kojima, Kazuko Kojima, Eizaburo Yamada, “Electronic Structure and Properties of Solids—Physics of Chemical Bonds”, published by Contemporary Engineering Co., p.269.
[0012]
Further, the P-type impurity, particularly Mg, diffuses to the active layer side, penetrates into a place other than the acceptor site of the crystal lattice, and compensates for the carriers in the p-type semiconductor layer immediately below the contact layer, thereby It has been found that the resistance of the p-type semiconductor layer is increased.
[0013]
The present invention has been made on the basis of the above findings, and a p-type contact layer in a light-emitting element using a group III-V compound semiconductor containing nitrogen has a group III-V containing phosphorus and nitrogen or arsenic and nitrogen. A compound is used.
[0014]
  A semiconductor light emitting device according to the present invention includes a substrate,Formed on the substrate III- A double heterostructure composed of a group V nitride semiconductor layer and a plurality of p-type conductive layers stacked on the double heterostructure III- A contact structure including a contact structure made of a group V nitride semiconductor layer and an electrode formed on the contact structure is configured. III- The group V nitride semiconductor layer is III Each containing aluminum as a group element and arsenic or phosphorus as a group V element and constituting a contact structure III- The ratio of nitrogen to arsenic or phosphorus in the group V nitride semiconductor layer increases stepwise from the electrode toward the double heterostructure.
[0015]
According to the semiconductor light emitting device, the second conductive layer is formed of the second conductive type second clad layer made of the III-V group compound containing nitrogen and the second group made of the III-V group compound containing phosphorus and nitrogen or arsenic and nitrogen. Since the conductive type contact layer is provided, the height of the Schottky barrier of the valence band between the electrode metal and the metal can be reduced as compared with the case where the second conductive type GaN is used for the contact layer.
[0021]
In the semiconductor light emitting device, the contact layer preferably contains aluminum. In this way, since AlN has a relatively small lattice constant, it can be lattice-matched with GaN by adding an appropriate amount of aluminum, so that a contact layer with few defects and good crystallinity can be obtained. .
[0022]
The semiconductor light emitting device preferably further includes a semiconductor layer made of AlN formed between the contact layer and the second cladding layer. In this case, since the atomic radius of Al is smaller than the atomic radius of Ga, which is a commonly used group III element, the gap in the AlN crystal is smaller than the gap in the GaN crystal. Type impurities cannot diffuse in the AlN crystal.
[0023]
DETAILED DESCRIPTION OF THE INVENTION
(First embodiment)
A first embodiment of the present invention will be described with reference to the drawings.
[0024]
FIG. 1 is a structural cross-sectional view of a semiconductor light emitting device according to a first embodiment of the present invention. As shown in FIG. 1, on a substrate 11 made of sapphire having a plane orientation of (0001), a buffer layer 12 made of undoped GaN and having a thickness of 30 nm for enhancing crystal lattice matching, and the buffer layer An n-type GaN layer 13 having a thickness of 3.0 μm and having a stepped portion on the upper portion is sequentially formed on the substrate 12.
[0025]
On the upper side of the stepped portion on the n-type GaN layer 13 is n-type Al._0.1 Ga_0.9 An n-type clad layer 14 as a first clad layer for containing carriers having a thickness of 500 nm and N, and a first guide layer 15 made of undoped GaN for enhancing the effect of carrier containment having a thickness of 100 nm. And undoped Ga_0.95In_0.05A barrier layer 16a made of N and having a thickness of 5 nm and undoped Ga_0.8 In_0.2An active layer 16b made of N layer and having a thickness of 2.5 nm is alternately stacked in a five-fold manner, and a multi-quantum well layer 16 in which another barrier layer 16a is further stacked thereon and undoped GaN. A second guide layer 17 having a thickness of 100 nm for enhancing the effect of carrier containment, and p-type Al_0.1 Ga_0.9 A p-type cladding layer 18 as a second cladding layer for containing carriers having a thickness of 500 nm, a p-type GaN layer 19 having a thickness of 300 nm, and p-type GaN._0.95P_0.05And a first metal film 22a made of Ni surrounded by a current narrowing layer 21 made of silicon oxide and having a T-shaped cross section and a leg portion having a T-shaped cross section, and the first metal film A positive electrode 22 formed by laminating a second metal film 22b made of Au is sequentially formed on 22a.
[0026]
Since sapphire, which is an insulator, is used for the substrate 11 and no negative electrode is provided on the back surface of the substrate, the Ti layer 24a and the Al layer 24b are provided on the lower side of the step portion on the n-type GaN layer 13. A negative electrode 24 is formed by laminating.
[0027]
Hereinafter, a method for manufacturing the semiconductor light emitting device configured as described above will be described.
[0028]
First, the main surface of the substrate 11 made of sapphire having a plane orientation of (0001) is subjected to a pretreatment such as cleaning using an organic solvent, and then the pressure is set to 70 × 133. The substrate 11 is heated in a hydrogen atmosphere of 3 Pa until the temperature reaches 1090 ° C., and the adsorbed gas, oxide, water molecules, etc. adhering to the surface of the substrate 11 are removed. Incidentally, the pressure unit Pa has a relationship of Torr and 133.3 Pa≈1 Torr.
[0029]
Thereafter, the temperature of the substrate 11 is lowered to 550 ° C., trimethylgallium is introduced onto the substrate 11 at a flow rate of 5.5 sccm, ammonia is introduced at a flow rate of 2.5 l / min, and silane is introduced onto the substrate 11. A buffer layer 12 made of undoped GaN is grown to a thickness of 30 nm. Thereafter, the temperature of the substrate 11 is increased to 1060 ° C., and trimethylgallium is introduced at a flow rate of 0.27 sccm, ammonia is introduced at a flow rate of 5.0 l / min, and silane is introduced at a flow rate of 12.5 sccm. An n-type GaN layer 13 having a thickness of 3.0 μm is grown on the buffer layer 12.
[0030]
Next, trimethylgallium is introduced onto the substrate 11 at a flow rate of 2.7 sccm, trimethylaluminum at a flow rate of 5.4 sccm, ammonia at a flow rate of 2.5 l / min, and silane at a flow rate of 12.5 sccm. N-type Al on the n-type GaN layer 13_0.1 Ga_0.9 An n-type cladding layer 14 made of N and having a thickness of 500 nm is grown.
[0031]
Next, trimethylgallium is introduced onto the substrate 11 at a flow rate of 2.7 sccm, and ammonia is introduced at a flow rate of 2.5 l / min. The n-type cladding layer 14 on the substrate 11 is made of undoped GaN and has a thickness of A 100 nm first guide layer 15 is grown.
[0032]
Next, the temperature of the substrate 11 is lowered to 730 ° C., and on the substrate 11, trimethylgallium is flowed at 2.7 sccm, trimethylindium is flowed at 27 sccm, ammonia is flowed at 10 l / min, and nitrogen is flowed at 10 l / min. The undoped Ga on the first guide layer 15 on the substrate 11_0.95In_0.05A barrier layer 16a made of N and having a thickness of 5.0 nm is grown. Subsequently, the temperature of the substrate 11 was left as it was, and trimethylgallium was introduced onto the substrate 11 at a flow rate of 10.8 sccm, trimethylindium at a flow rate of 27 sccm, ammonia at a flow rate of 10 l / min, and nitrogen at a flow rate of 10 l / min. , Undoped Ga on the barrier layer 16a_0.8 In_0.2 An active layer 16b made of N and having a thickness of 2.5 nm is grown. After repeating the film formation of a total of five pairs of these barrier layers 16a and active layers 16b as a pair, another barrier layer 16a is stacked thereon to form multiple quantum layers stacked alternately in five layers. The well layer 16 is formed.
[0033]
Next, the temperature of the substrate 11 is increased to 1060 ° C., trimethyl gallium is introduced onto the substrate 11 at a flow rate of 2.7 sccm, and ammonia is introduced at a flow rate of 2.5 l / min. A second guide layer 17 made of undoped GaN and having a thickness of 100 nm is grown on 16.
[0034]
Thereafter, trimethylgallium was introduced onto the substrate 11 at a flow rate of 2.7 sccm, trimethylaluminum at a flow rate of 5.4 sccm, ammonia at a flow rate of 2.5 l / min, and cyclopentadienyl magnesium at a flow rate of 5.0 sccm. P-type Al on the second guide layer 17 on the substrate 11._0.1 Ga_0.9 A p-type cladding layer 18 made of N and having a thickness of 500 nm is grown. Next, p-type cladding on the substrate 11 is introduced onto the substrate 11 by introducing trimethylgallium at a flow rate of 2.7 sccm, ammonia at a flow rate of 5.0 l / min, and cyclopentadienyl magnesium at a flow rate of 5.0 sccm. A p-type GaN layer 19 having a thickness of 300 nm is grown on the layer 18.
[0035]
Next, the temperature of the substrate 11 is lowered to 680 ° C., trimethylgallium is supplied at a flow rate of 2.7 sccm, phosphine is supplied at a flow rate of 27 sccm, ammonia is supplied at a flow rate of 10 l / min, and cyclopentadienylmagnesium is supplied over the substrate 11. By introducing at 5.0 sccm, p-type GaN is formed on the p-type GaN layer 19 on the substrate 11._0.95P_0.05The contact layer 20 having a thickness of 100 nm is grown.
[0036]
Next, the formed substrate 11 is annealed in a nitrogen atmosphere at a temperature of 700 ° C. for 1 hour, and impurity ions in the p-type cladding layer 18, the p-type GaN layer 19, and the contact layer 20 are used. A certain Mg is activated.
[0037]
Next, a method for forming the positive electrode 22 and the negative electrode 24 on the annealed substrate 11 will be described.
[0038]
First, after forming a mask pattern having an opening in the positive electrode 22 formation region on the contact layer 20 in the substrate 11, Ni for mask having a thickness of 1 μm is deposited on the entire surface of the substrate. Next, after removing the mask pattern, the pressure is 133.3 mPa, the RF power is 400 W, the RF frequency is 13.56 MHz, and the substrate 11 in the ECR plasma composed of chlorine and hydrogen with a mixing ratio of 1: 1. The voltage between the substrate holder to be held and the grid is set to 400 V, and the substrate 11 is dry-etched for 20 minutes using the masking Ni as a mask to expose the n-type GaN layer 13. Thereafter, the masking Ni is removed using nitric acid in a nitrogen atmosphere at atmospheric pressure. In place of Ni for mask, metal such as aluminum or SiO₂ A dielectric such as the above may be used.
[0039]
Next, a SiO film having a film thickness of 100 nm is formed on the entire surface of the substrate 11 by CVD.₂ A dielectric film is deposited. The CVD method may be a photo CVD method or a plasma CVD method.
[0040]
Subsequently, after applying a resist film over the entire surface of the dielectric film on the substrate 11, a positive electrode formation region on the upper surface of the contact layer 20 on the substrate 11 and n on the substrate 11 are used by photolithography. A resist pattern having an opening having a width of 10 μm is selectively formed in the negative electrode formation region on the exposed surface of the n-type GaN layer 13, and using the resist pattern as a mask, the mixture ratio is 1:10. Wet etching is performed on the substrate 11 using an aqueous solution of ammonium fluoride, and openings are formed in the positive electrode formation region on the upper surface of the contact layer 20 and in the negative electrode formation region on the exposed surface of the n-type GaN layer 13, respectively. And SiO₂ A current narrowing layer 21 is formed. In this case, unlike the semiconductor light emitting device shown in FIG. 1, a current narrowing layer 21 similar to the positive electrode 22 is formed on the negative electrode 24.
[0041]
Next, acetone and O₂ After removing the resist pattern on the substrate 11 using plasma, the current narrowing layer 21 on the upper surface of the contact layer 20, the first metal film 22 a made of Ni in the opening of the current narrowing layer 21, and the first A positive electrode 22 is formed by sequentially depositing a second metal film 22b made of Au on the metal film 22a.
[0042]
Next, a negative electrode 24 is formed by sequentially depositing a current narrowing layer on the upper surface of the n-type GaN layer 13 and a Ti layer 24a and an Al layer 24b in the opening of the current narrowing layer.
[0043]
Next, the substrate 11 is cleaved so that the cavity length is 0.5 mm to complete the semiconductor light emitting device.
[0044]
Hereinafter, the characteristics of the semiconductor light emitting device according to this embodiment will be described.
[0045]
First, the optical characteristics are that the oscillation wavelength of laser light is 410 nm, and the reflectance of the end face is 22% for both the front and rear. The internal loss of laser light is 5cm^-1The loss in the resonator is 20cm^-1It is.
[0046]
Next, electrical characteristics will be described.
[0047]
The carrier density of each of the p-type cladding layer 18 and the n-type cladding layer 14 is 1 × 10.¹⁸/ Cm^Three The carrier densities of the p-type GaN layer 19 and the n-type GaN layer 13 are 3 × 10 3 respectively.¹⁸/ Cm^Three The carrier density of the contact layer 20 is 3 × 10¹⁸/ Cm^Three It is.
[0048]
The mobility is 10 cm for each of the p-type cladding layer 18, the p-type GaN layer 19 and the contact layer 20.² / V · s, and the n-type cladding layer 14 and the n-type GaN layer 13 are each 250 cm.² Since / V · s, the p-type cladding layer 18, the n-type cladding layer 14, the p-type GaN layer 19, and the n-type GaN layer 13 having sufficiently low resistivity are realized.
[0049]
On the positive electrode 22 side, the contact resistance is 1 × 10 between the p-type contact layer 20 and Ni which is the first metal film 22a in contact with the contact layer 20.^-3Ω · cm² Similarly, ohmic contact is also realized between the n-type GaN layer 13 and the Ti layer 24a on the negative electrode 24 side.
[0050]
Realized between the p-type contact layer 20 and Ni, the contact resistance is 1 × 10^-3Ω · cm² The ohmic contact is reduced to 1/10 of the contact resistance between the conventional p-type GaN contact layer and Ni described above. This is because the potential barrier of the valence band between the p-type contact layer 20 and Ni is 0.35 eV, and the valence band between the conventional p-type GaN contact layer and Ni shown in FIG. This is because the potential barrier is 0.44 eV smaller than 0.79 eV.
[0051]
As can be seen from FIG. 11, when the heterojunction between GaN and GaP or GaN and GaAs shown in this embodiment is performed, a so-called type II heterojunction shown in FIG. 12B is realized. it can.
[0052]
FIG. 2 is a graph showing current-voltage characteristics of the semiconductor light emitting device according to this embodiment. In FIG. 2, 1A is a curve representing the output power of the semiconductor light emitting device according to this embodiment, and 1B is a curve representing the forward voltage applied to the semiconductor light emitting device according to this embodiment. On the other hand, 10A is a curve representing the output power of the conventional semiconductor light emitting device, and 10B is a curve representing the forward voltage applied to the conventional semiconductor light emitting device. In FIG. 2, it can be seen that the threshold voltage of the semiconductor light emitting device according to the present embodiment is 4.8 V as shown by curve 1A, and the threshold current is 110 mA as shown by curve 1B. On the other hand, the threshold voltage of the conventional semiconductor light emitting device is 8V as shown by a curve 10A, and the threshold current is 130 mA as shown by a curve 10B. The threshold current density is 2 kA / cm for the semiconductor light emitting device according to this embodiment.² The conventional semiconductor light emitting device is 9 kA / cm.² It is. Thus, it can be seen that the current-voltage characteristics of the semiconductor light emitting device according to the present embodiment are reduced by 40% in the forward voltage and 78% in the threshold current density as compared with the conventional semiconductor light emitting device. This is because the ohmic contact between the p-type contact layer 20 and Ni constituting the positive electrode 22 is one tenth of the contact resistance between the conventional p-type GaN contact layer and Ni. is there.
[0053]
Thus, according to the present embodiment, the contact layer 20 for making ohmic contact with the positive electrode 22 is made of GaN having Mg as an impurity._0.95P_0.05Since the contact resistance is reduced, the operating voltage of the semiconductor light emitting element can be reduced.
[0054]
P-type GaN_0.95P_0.05P-type GaN instead of the contact layer 20 made of_0.95As_0.05Similar results can be obtained using a contact layer made of the same.
[0055]
In addition, p-type GaN_0.95P_0.05Instead of the contact layer 20, it is doped p-type and has a laminated structure with each other (GaN)_m (GaP)_n (However, m and n are natural numbers. The same shall apply hereinafter.) A similar result can be obtained using a contact layer.
[0056]
Furthermore, GaAs or GaAs instead of GaP_1-x P_x A similar result can be obtained using.
[0057]
The first metal layer 22a of the negative electrode 22 that contacts the p-type contact layer 20 is not limited to Ni, but may be platinum (Pt), gold (Au), or palladium (Pd).
[0058]
Further, instead of the substrate 11 made of sapphire, a substrate made of SiC, ZnO, MgAl₂ O_Four Or LiAlO₂ A substrate made of an oxide such as SiC or a SiC inclined substrate may be used.
[0059]
(Modification of the first embodiment)
Hereinafter, a modification of the first embodiment of the present invention will be described with reference to the drawings.
[0060]
FIG. 3 is a structural cross-sectional view of a semiconductor light emitting device according to a modification of the first embodiment of the present invention. The difference from the first embodiment is that, as shown in FIG. 3, the contact layer 20 formed between the p-type GaN layer 19 and the first metal film 22a is the negative electrode 22, that is, the first This is that the first, second, and third contact layers 20a, 20b, and 20c made of p-type GaNP are formed so that the composition ratio of nitrogen gradually decreases toward the metal film 22a. . Specifically, the p-type GaN layer sequentially from the p-type GaN layer 19 side._0.99P_0.01First contact layer 20a comprising p-type GaN_0.97P_0.03Second contact layer comprising layer 20b and p-type GaN_0.95P_0.05A third contact layer 20c is formed.
[0061]
In FIG. 3, the same members as those of the semiconductor light emitting element shown in FIG.
[0062]
A method for manufacturing the contact layer 20 including the first contact layer 20a, the second contact layer 20b, and the third contact layer 20c according to this modification will be described.
[0063]
After growing up to the p-type GaN layer 19 on the substrate 11 made of sapphire having a plane orientation of (0001), the temperature of the substrate 11 is set to 680 ° C. On the substrate 11, trimethylgallium was introduced at a flow rate of 2.7 sccm, phosphine at a flow rate of 13 sccm, ammonia at a flow rate of 10 l / min, and cyclopentadienylmagnesium at a flow rate of 5.0 sccm. p-type GaN on the p-type GaN layer 19_0.99P_0.01The first contact layer 20a having a thickness of 30 nm is grown. Next, trimethylgallium is introduced onto the substrate 11 at a flow rate of 2.7 sccm, phosphine at a flow rate of 40 sccm, ammonia at a flow rate of 10 l / min, and cyclopentadienyl magnesium at a flow rate of 5.0 sccm. On the first contact layer 20a on the upper side, p-type GaN_0.97P_0.03The second contact layer 20b having a thickness of 30 nm is grown. Next, trimethylgallium was introduced at a flow rate of 2.7 sccm, phosphine at a flow rate of 65 sccm, ammonia at a flow rate of 10 l / min, and cyclopentadienylmagnesium at a flow rate of 5.0 sccm. P-type GaN having a thickness of 30 nm on the contact layer 20b_0.95P_0.05Layer 20c is grown.
[0064]
After that, the substrate 11 is annealed using the same method as in the first embodiment, and then the positive electrode 22 and the negative electrode 24 are formed, and further cleaved to complete the light emitting element.
[0065]
Hereinafter, characteristics of the semiconductor light emitting device according to this modification will be described.
[0066]
First, the optical characteristics are the same as in the first embodiment, the oscillation wavelength of the laser light is 410 nm, and the reflectance of the end face is 22% for both the front and rear. The internal loss of the laser is 5cm^-1The loss in the resonator is 20cm^-1It is.
[0067]
Next, electrical characteristics will be described.
[0068]
The carrier density of the p-type cladding layer 19 and the n-type cladding layer 13 is 1 × 10 3 respectively.¹⁸/ Cm^Three The carrier densities of the p-type GaN layer 19 and the n-type GaN layer 13 are 3 × 10 3 respectively.¹⁸/ Cm^Three The carrier density of the contact layer 20 is 3 × 10¹⁸/ Cm^Three It is.
[0069]
The mobility is 10 cm for each of the p-type cladding layer 18, the p-type GaN layer 19 and the contact layer 20.² / V · s, and the n-type cladding layer 14 and the n-type GaN layer 13 are each 250 cm.² Since / V · s, the p-type cladding layer 18, the n-type cladding layer 14, the p-type GaN layer 19, and the n-type GaN layer 13 having sufficiently low resistivity are realized.
[0070]
On the positive electrode 22 side, the contact resistance between the p-type contact layer 20 and the Ni of the first metal film 22a in contact with the contact layer 20 is 3 × 10^-FourΩ · cm² Similarly, ohmic contact is also realized between the n-type GaN layer 13 and the Ti layer 24a on the negative electrode 24 side.
[0071]
It is realized between the contact layer 20 composed of three p-type layers and Ni, and the contact resistance is 3 × 10^-FourΩ · cm² The ohmic contact is reduced to 1/30 of the contact resistance between the conventional p-type GaN contact layer and Ni. This is because the potential barrier of the valence band between the p-type contact layer 20 and Ni becomes 0.17 eV, and the potential barrier of the valence band between the conventional p-type GaN contact layer and Ni is 0. This is because it is 0.62 eV smaller than 79 eV.
[0072]
In addition, the p-type contact layer 20 including the first contact layer 20a, the second contact layer 20b, and the third contact layer 20c according to the present modification includes nitrogen (N) with respect to phosphorus (P). Is configured to increase stepwise from the contact layer 20 side toward the p-type cladding layer 18, so that each layer of the contact layer 20 moves away from Ni of the negative electrode 22, that is, p As the GaN band 19 is approached, the band edge energy of the valence band of the contact layer 20 becomes farther from the vacuum level and approaches the band edge energy of the valence band of the p-type GaN layer 19. This is because the potential barrier against holes in the p-type GaN layer 19 immediately below the contact layer 20 becomes small.
[0073]
FIG. 4 is a graph showing current-voltage characteristics of the semiconductor light emitting device according to this modification. In FIG. 4, 2A is a curve representing the output power of the semiconductor light emitting device according to this modification, and 2B is a curve representing the forward voltage applied to the semiconductor light emitting device according to this modification. On the other hand, 10A is a curve representing the output power of the conventional semiconductor light emitting device, and 10B is a curve representing the forward voltage applied to the conventional semiconductor light emitting device. In FIG. 4, it can be seen that the threshold voltage of the semiconductor light emitting device according to this modification is 4.5 V as shown by curve 2A, and the threshold current is 100 mA as shown by curve 2B. On the other hand, the threshold voltage of the conventional semiconductor light emitting device is 8V as shown by a curve 10A, and the threshold current is 130 mA as shown by a curve 10B. The threshold current density is 1.8 kA / cm for the semiconductor light emitting device according to this variation.² The conventional semiconductor light emitting device is 9 kA / cm.² It is. Thus, it can be seen that the current-voltage characteristics of the semiconductor light emitting device according to this modification are clearly improved as compared with the conventional semiconductor light emitting device. This is because the ohmic contact between the p-type contact layer 20 composed of three layers and Ni constituting the positive electrode 22 is one-third of the contact resistance between the conventional p-type GaN contact layer and Ni. Because.
[0074]
As described above, according to this modification, the contact layer 20 for making ohmic contact with the positive electrode 22 has a stepwise increase in the ratio of nitrogen to phosphorus from the contact layer 20 side toward the p-type GaN layer 19. Since the band edge energy of the valence band of the contact layer 20 is far from the vacuum level and approaches the band edge energy of the valence band of the p-type GaN layer 19, the contact resistance is further reduced. As a result, the forward voltage of the semiconductor light emitting device can be reduced by 43%.
[0075]
Note that p-type GaN is used as the p-type contact layer 20._1-x P_x (Where x is a real number of 0.07 <x <1), the potential barrier of the valence band between the contact layer 20 and Ni can be reduced to 0, which is ideal. Ohmic contact can be obtained.
[0076]
Further, p-type GaN is used as the p-type contact layer 20._1-x P_x (Where x is a real number such that 0 <x <1; the same applies hereinafter) p-type GaN_1-x As_x The same effect can be obtained even if is used.
[0077]
Further, each layer of the contact layer 20 is made of (GaN)_m (GaP)_n Or (GaN)_m (GaAs)_n (GaN)_m (GaAs_1-x P_x )_n May be used.
[0078]
Further, the first metal layer 22a of the negative electrode 22 that contacts the p-type contact layer 20 is not limited to Ni, but may be Pt, Au, or Pd.
[0079]
Also, instead of the substrate 11 made of sapphire, a substrate made of SiC, Al₂ O_Three , ZnO, MgAl₂ O_Four Or LiAlO₂ A substrate made of an oxide such as may be used, and the same effect can be obtained by using a SiC inclined substrate.
[0080]
(Second Embodiment)
Hereinafter, a second embodiment of the present invention will be described with reference to the drawings.
[0081]
FIG. 5 is a structural cross-sectional view of a semiconductor light emitting device according to the second embodiment of the present invention. As shown in FIG. 5, the semiconductor light emitting device according to this embodiment includes a p-type Al layer between the p-type GaN layer 19 and the first metal film 22 a constituting the negative electrode 22._0.1 Ga_0.9 N_0.989 P_0.011 A contact layer 30 is formed.
[0082]
In FIG. 5, the same members as those of the semiconductor light emitting element shown in FIG.
[0083]
A method for manufacturing the contact layer 30 according to this embodiment will be described.
[0084]
First, as in the first embodiment, the substrate 11 made of sapphire having a plane orientation of (0001) is cleaned and pretreated using an organic solvent, and then the p-type GaN layer 19 is formed on the substrate 11. Growing up until.
[0085]
Next, the temperature of the substrate 11 is set to 680 ° C., trimethylaluminum at a flow rate of 10 sccm, trimethylgallium at a flow rate of 20 sccm, phosphine at a flow rate of 27 sccm, ammonia at a flow rate of 10 l / min, and cyclopenta on the substrate 11. Dienylmagnesium is introduced at a flow rate of 5.0 sccm, and p-type Al is formed on the p-type GaN layer 19 on the substrate 11._0.1 Ga_0.9 N_0.989 P_0.011 The contact layer 30 having a thickness of 100 nm is grown.
[0086]
After that, as in the first embodiment, the substrate 11 is annealed to activate the impurity Mg, and then the positive electrode 22 and the negative electrode 24 are formed, so that the desired cavity length is obtained. The substrate 11 is cleaved to complete the light emitting element.
[0087]
Hereinafter, the characteristics of the semiconductor light emitting device according to this embodiment will be described.
[0088]
First, the optical characteristics are the same as in the first embodiment, the laser oscillation wavelength is 410 nm, and the reflectance of the end face is 22% for both the front and rear. The internal loss of the laser is 5cm^-1The loss in the resonator is 20cm^-1It is.
[0089]
Next, electrical characteristics will be described.
[0090]
The carrier density of the p-type cladding layer 19 and the n-type cladding layer 13 is 1 × 10 3 respectively.¹⁸/ Cm^Three The carrier densities of the p-type GaN layer 19 and the n-type GaN layer 13 are 3 × 10 3 respectively.¹⁸/ Cm^Three The carrier density of the contact layer 30 is 3 × 10¹⁸/ Cm^Three It is.
[0091]
The mobility is 10 cm for each of the p-type cladding layer 18, the p-type GaN layer 19 and the contact layer 30.² / V · s, and the n-type cladding layer 14 and the n-type GaN layer 13 are each 250 cm.² Since / V · s, the p-type cladding layer 18, the n-type cladding layer 14, the p-type GaN layer 19, and the n-type GaN layer 13 having sufficiently low resistivity are realized.
[0092]
On the positive electrode 22 side, the contact resistance between the p-type contact layer 30 and the Ni of the first metal film 22a in contact with the contact layer 30 is 1 × 10^-3Ω · cm² Similarly, ohmic contact is also realized between the n-type GaN layer 13 and the Ti layer 24a on the negative electrode 24 side.
[0093]
p-type Al_0.1 Ga_0.9 N_0.989 P_0.011 It is realized between the contact layer 30 made of Ni and Ni, and the contact resistance is 1 × 10^-3Ω · cm² The ohmic contact is reduced to 1/10 of the contact resistance between the conventional p-type GaN contact layer and Ni. This is because the potential barrier of the valence band between the p-type contact layer 30 and Ni becomes 0.43 eV, and the potential barrier of the valence band between the conventional p-type GaN contact layer and Ni becomes 0. 3 eV. This is because it is 0.36 eV smaller than 79 eV.
[0094]
FIG. 6 is a graph showing current-voltage characteristics of the semiconductor light emitting device according to this embodiment. In FIG. 6, 3A is a curve representing the output power of the semiconductor light emitting device according to this embodiment, and 3B is a curve representing the forward voltage applied to the semiconductor light emitting device according to this embodiment. On the other hand, 10A is a curve representing the output power of the conventional semiconductor light emitting device, and 10B is a curve representing the forward voltage applied to the conventional semiconductor light emitting device. In FIG. 6, it can be seen that the threshold voltage of the semiconductor light emitting device according to the present embodiment is 4.8 V as shown by curve 3A, and the threshold current is 110 mA as shown by curve 3B. On the other hand, the threshold voltage of the conventional semiconductor light emitting device is 8V as shown by a curve 10A, and the threshold current is 130 mA as shown by a curve 10B. The threshold current density is 2 kA / cm for the semiconductor light emitting device according to this embodiment.² The conventional semiconductor light emitting device is 9 kA / cm.² It is. Thus, it can be seen that the current-voltage characteristics of the semiconductor light emitting device according to this embodiment are clearly improved as compared with the conventional semiconductor light emitting device. This is because the ohmic contact between the p-type contact layer 30 and the Ni constituting the positive electrode 22 is one tenth of the contact resistance between the conventional p-type GaN contact layer and Ni. is there.
[0095]
As a feature of this embodiment, as shown in FIG. 13, since AlN has a relatively small lattice constant, p-type Al_0.1 Ga_0.9 N_0.989 P_0.011 Since the contact layer 30 made of this can perfectly lattice match with GaN, its defect density is 1 × 10⁹ / Cm² It becomes. This value is the conventional p-type Ga_1-x In_x A contact layer having a thickness one order of magnitude smaller than that of the N contact layer and having a thickness of 50 nm or more can be reliably formed.
[0096]
The contact layer 30 has a p-type Al._0.1 Ga_0.9 N_0.989 P_0.011 P-type Al instead of_x Ga_1-x N_1-y As_y The same effect can be obtained by using.
[0097]
P-type Al_0.1 Ga_0.9 N_0.989 P_0.011 Instead of (AlN)_h (AlAs)_k (GaN)_m (GaAs)_n A contact layer made of (where k is an integer and h, m, and n are natural numbers) may be used.
[0098]
Further, the first metal layer 22a of the negative electrode 22 that contacts the p-type contact layer 30 is not limited to Ni, but may be Pt, Au, or Pd.
[0099]
Also, instead of the substrate 11 made of sapphire, a substrate made of SiC, Al₂ O_Three , ZnO, MgAl₂ O_Four Or LiAlO₂ A substrate made of an oxide such as SiC may be used, and a SiC inclined substrate may be used.
[0100]
(Third embodiment)
Hereinafter, a third embodiment of the present invention will be described with reference to the drawings.
[0101]
FIG. 7 is a sectional view showing the structure of a semiconductor light emitting device according to the third embodiment of the present invention. As shown in FIG. 7, the semiconductor light emitting device according to this embodiment is formed on the p-type GaN layer 19 between the p-type GaN layer 19 and the first metal film 22 a constituting the negative electrode 22. A first contact layer 40a made of p-type AlN and p-type GaN formed on the first contact layer 40a_0.98P_0.02It has a contact layer 40 composed of a second contact layer 40b made of layers.
[0102]
In FIG. 7, the same members as those of the semiconductor light emitting element shown in FIG.
[0103]
A method for manufacturing the two-layer contact layer 40 according to this embodiment will be described.
[0104]
First, as in the first embodiment, the substrate 11 made of sapphire having a plane orientation of (0001) is cleaned and pretreated using an organic solvent, and then the p-type GaN layer 19 is formed on the substrate 11. Growing up until.
[0105]
Next, the temperature of the substrate 11 is set to 680 ° C., trimethylaluminum is introduced at a flow rate of 4.1 sccm, ammonia is introduced at a flow rate of 10 l / min, and cyclopentadienylmagnesium is introduced onto the substrate 11 at a flow rate of 5.0 sccm. Then, a first contact layer 40 a made of p-type AlN and having a thickness of 2 nm is grown on the p-type GaN layer 19 on the substrate 11.
[0106]
Subsequently, trimethylgallium was introduced onto the substrate 11 at a flow rate of 2.7 sccm, phosphine at a flow rate of 27 sccm, ammonia at a flow rate of 10 l / min, and cyclopentadienyl magnesium at a flow rate of 5.0 sccm. P-type GaN is formed on the first contact layer 40a._0.98P_0.02The second contact layer 40b having a thickness of 11.5 nm is grown.
[0107]
Thereafter, as in the first embodiment, the substrate 11 is annealed to activate the impurity Mg, and then the positive electrode 22 and the negative electrode 24 are formed, and the substrate 11 is further cleaved to emit light. Complete the device.
[0108]
Hereinafter, the characteristics of the semiconductor light emitting device according to this embodiment will be described.
[0109]
First, the optical characteristics are the same as in the first embodiment, the laser oscillation wavelength is 410 nm, and the reflectance of the end face is 22% for both the front and rear. The internal loss of the laser is 5cm^-1The loss in the resonator is 20cm^-1It is.
[0110]
Next, electrical characteristics will be described.
[0111]
The carrier density of the p-type cladding layer 19 and the n-type cladding layer 13 is 1 × 10 3 respectively.¹⁸/ Cm^Three The carrier densities of the p-type GaN layer 19 and the n-type GaN layer 13 are 3 × 10 3 respectively.¹⁸/ Cm^Three , And the carrier density of the contact layer 40 is 3 × 10.¹⁸/ Cm^Three It is.
[0112]
The mobility is 10 cm for each of the p-type cladding layer 18, the p-type GaN layer 19 and the contact layer 40.² / V · s, and the n-type cladding layer 14 and the n-type GaN layer 13 are each 250 cm.² Since / V · s, the p-type cladding layer 18, the n-type cladding layer 14, the p-type GaN layer 19, and the n-type GaN layer 13 having sufficiently low resistivity are realized.
[0113]
On the positive electrode 22 side, the first contact layer 40a made of p-type AlN and p-type GaN_0.98P_0.02The contact resistance between the contact layer 40 made of the second contact layer 40b made of a layer and the Ni of the first metal film 22a in direct contact with the contact layer 40 is 1 × 10^-3Ω · cm² Similarly, ohmic contact is also realized between the n-type GaN layer 13 and the Ti layer 24a on the negative electrode 24 side.
[0114]
Realized between the p-type contact layer 40 and Ni, the contact resistance is 1 × 10^-3Ω · cm² The ohmic contact is reduced to 1/10 of the contact resistance between the conventional p-type GaN contact layer and Ni.
[0115]
This is because the potential barrier of the valence band between the p-type contact layer 40 and Ni becomes 0.53 eV, and the potential barrier of the valence band between the conventional p-type GaN contact layer and Ni is 0. This is because it is 0.26 eV smaller than 79 eV.
[0116]
FIG. 8 is a graph showing current-voltage characteristics of the semiconductor light emitting device according to this embodiment. In FIG. 8, 4A is a curve representing the output power of the semiconductor light emitting device according to this embodiment, and 4B is a curve representing the forward voltage applied to the semiconductor light emitting device according to this embodiment. On the other hand, 10A is a curve representing the output power of the conventional semiconductor light emitting device, and 10B is a curve representing the forward voltage applied to the conventional semiconductor light emitting device. In FIG. 8, it can be seen that the threshold voltage of the semiconductor light emitting device according to the present embodiment is 4.8 V as shown by the curve 4A, and the threshold current is 110 mA as shown by the curve 4B. On the other hand, the threshold voltage of the conventional semiconductor light emitting device is 8V as shown by a curve 10A, and the threshold current is 130 mA as shown by a curve 10B. The threshold current density is 2 kA / cm for the semiconductor light emitting device according to this embodiment.² The conventional semiconductor light emitting device is 9 kA / cm.² It is. Thus, it can be seen that the current-voltage characteristics of the semiconductor light emitting device according to this embodiment are clearly improved as compared with the conventional semiconductor light emitting device. This is because the ohmic contact between the contact layer 40 composed of two p-type layers and Ni constituting the positive electrode 22 is one tenth of the contact resistance between the conventional p-type GaN contact layer and Ni. Because.
[0117]
Further, the p-type two-layer contact layer 40 is lattice-matched to GaN, and its defect density is 1 × 10 6.⁹ / Cm² It is. This value is the conventional p-type Ga_1-x In_x The value is an order of magnitude smaller than that of the N contact layer.
[0118]
Further, as a feature of the present embodiment, the p-type contact layer 40 has a p-type Al as the first contact layer 40a._0.1 Ga_0.9 Since the AlN layer is provided on the p-type cladding layer 18 made of N, the atomic radius of Al is smaller than the atomic radius of Ga as shown in FIG. As a result, the p-type impurity Mg substituted for Al cannot diffuse in the AlN crystal. Accordingly, it is possible to suppress the diffusion of Mg, which is a p-type impurity, from the contact layer 40, which is usually doped with a large impurity concentration in order to enhance conductivity, to the active layer side.
[0119]
Hereinafter, a state in which the diffusion of Mg is suppressed will be described with reference to the drawings.
[0120]
FIG. 9 is a graph showing the concentration of Mg, which is a p-type impurity, in the semiconductor light emitting device according to this embodiment and the conventional semiconductor light emitting device analyzed using a secondary ion mass spectrometer (SIMS). In FIG. 9, a curve 5 represents the Mg concentration of the semiconductor light emitting device according to the present embodiment, and a curve 11 represents the Mg concentration of the conventional semiconductor light emitting device. The scale A representing the depth direction represents the semiconductor light emitting device according to the present embodiment, the scale B represents a conventional semiconductor light emitting device, and the reference numerals thereof correspond to the respective semiconductor layers or metal layers. As shown by curve 5 in FIG. 9, the Mg concentration of the semiconductor light emitting device according to the present embodiment sharply decreases at the interface between the second contact layer 40b and the first contact layer 40a. It can be seen that the second guide layer 17 is hardly reached. On the other hand, in the case of the conventional semiconductor light emitting device shown by the curve 11, it can be seen that Mg diffuses from the p-type contact layer 111 beyond the multiple quantum well layer 107.
[0121]
Thus, according to the present embodiment, since the first contact layer 40a of the p-type contact layer 40 composed of two layers is made of AlN, the semiconductor layer made of AlN causes p-type impurities. The diffusion of Mg from the contact layer 40 to the p-type GaN layer 19 joined to the contact layer 40 is suppressed. Thereby, there is no possibility that the impurity Mg penetrates into a place other than the acceptor site of the crystal and compensates the p-type carrier, and the conductivity of the p-type GaN layer 19 in contact with the p-type contact layer 40 is not lowered. Since the voltage applied to the p-type GaN layer 19 becomes small, the operating voltage of the light emitting element can be reduced.
[0122]
The p-type GaN constituting the second contact layer 40b_0.98P_0.02P-type GaN instead of_1-x As_x May be used.
[0123]
The first metal layer 22a of the negative electrode 22 that contacts the p-type contact layer 40 is not limited to Ni, but may be Pt, Au, or Pd.
[0124]
Also, instead of the substrate 11 made of sapphire, a substrate made of SiC, Al₂ O_Three , ZnO, MgAl₂ O_Four Or LiAlO₂ A substrate made of an oxide such as may be used, and the same effect can be obtained by using a SiC inclined substrate.
[0125]
【The invention's effect】
According to the semiconductor light emitting device of the present invention, the III-V group compound containing phosphorus and nitrogen or arsenic and nitrogen formed on the second conductivity type second cladding layer made of the III-V group compound containing nitrogen. Since the second conductivity type contact layer is provided, the Schottky barrier height of the valence band between the electrode metal and the GaN is reduced as compared with the case where the second conductivity type GaN is used for the contact layer. Therefore, the threshold voltage is reduced, and low voltage driving can be realized.
[0126]
In the semiconductor light emitting device, the composition of the contact layer of the second conductivity type is a general formula GaN_1-xP_x (However, x in the formula is a real number of 0 <x <1.) Therefore, the valence band between the electrode metal and the GaN of the second conductivity type is larger than that in the case where the second conductivity type GaN is used for the contact layer. The height of the Schottky barrier can be surely reduced.
[0127]
Further, in the semiconductor light emitting device, the composition of the second conductivity type contact layer has the general formula GaN._1-xAs_x (However, x in the formula is a real number of 0 <x <1.) Therefore, the valence band between the electrode metal and the GaN of the second conductivity type is larger than that in the case where the second conductivity type GaN is used for the contact layer. The height of the Schottky barrier can be surely reduced.
[0128]
Further, in the semiconductor light emitting device, the second conductivity type contact layer is composed of a plurality of layers, and the ratio of nitrogen to phosphorus or arsenic in each of the plurality of layers is a second group composed of a III-V group compound containing nitrogen from the electrode side. Since it is configured to increase stepwise toward the cladding layer, the band edge energy of the valence band of the contact layer becomes farther from the vacuum level as it approaches the second cladding layer, and the second cladding Since it approaches the band edge energy of the valence band of the layer, the potential barrier against holes formed at the interface between the contact layer and the second cladding layer is reduced. For this reason, since the threshold voltage is further reduced, further low voltage driving can be realized.
[0129]
Further, in the semiconductor light emitting device, the second conductivity type is p-type, and the contact layer reduces the threshold voltage for reducing the potential barrier against holes generated by contact with the electrode. Voltage drive can be realized reliably.
[0130]
Further, in the semiconductor light emitting device, since the size of the potential barrier with respect to the holes is zero, the threshold voltage is further reduced, so that further low voltage driving can be realized with certainty.
[0131]
In the semiconductor light emitting device, since the second conductivity type contact layer contains aluminum, it can be lattice-matched with a III-V group compound containing nitrogen and has good crystallinity. Surely obtained
In addition, since the semiconductor light emitting device further includes a semiconductor layer made of AlN formed between the second conductivity type contact layer and the second conductivity type second cladding layer, there is no gap in the AlN crystal. Since the gap is smaller than the gap in the GaN crystal, the second conductivity type impurity substituted for Al cannot diffuse in the AlN crystal. As a result, the second conductivity type carriers are not compensated for by the second conductivity type impurities in the second cladding layer, so that the conductivity of the second cladding layer is not lowered. Therefore, the operating voltage can be reduced.
[Brief description of the drawings]
FIG. 1 is a configuration cross-sectional view of a semiconductor light emitting device according to a first embodiment of the present invention.
FIG. 2 is a graph showing current-voltage characteristics of the semiconductor light emitting element according to the first embodiment of the present invention.
FIG. 3 is a structural cross-sectional view of a semiconductor light emitting element according to a modification of the first embodiment of the present invention.
FIG. 4 is a graph showing current-voltage characteristics of a semiconductor light emitting device according to a modification of the first embodiment of the present invention.
FIG. 5 is a structural cross-sectional view of a semiconductor light emitting element according to a second embodiment of the present invention.
FIG. 6 is a graph showing current-voltage characteristics of a semiconductor light emitting device according to a second embodiment of the present invention.
FIG. 7 is a structural cross-sectional view of a semiconductor light emitting device according to a third embodiment of the present invention.
FIG. 8 is a graph showing current-voltage characteristics of a semiconductor light emitting device according to a third embodiment of the present invention.
FIG. 9 is a graph showing a Mg concentration as a p-type impurity in a semiconductor light emitting device according to a third embodiment of the present invention and a conventional semiconductor light emitting device.
FIG. 10 is a cross-sectional view of a conventional semiconductor light emitting device.
FIG. 11 is a graph showing band gap energy of a typical group III-V compound semiconductor.
FIG. 12 is a diagram showing type I and type II band gap energies in a heterojunction.
FIG. 13 is a graph showing the relationship between the lattice constant and the band gap energy of a typical III-V compound semiconductor.
[Explanation of symbols]
11 Substrate
12 Buffer layer
13 n-type GaN layer
14 n-type cladding layer (first cladding layer)
15 First guide layer
16a barrier layer
16b Active layer
16 Multiple quantum well layers
17 Second guide layer
18 p-type cladding layer (second cladding layer)
19 p-type GaN layer
20 Contact layer
20a First contact layer
20b Second contact layer
20c Third contact layer
21 Current narrowing layer
22a First metal film
22b Second metal film
22 Positive electrode
24a Ti layer
24b Al layer
24 Negative electrode
30 Contact layer
40 Contact layer
40a First contact layer (semiconductor layer made of AlN)
40b Second contact layer

Claims (4)

A substrate,
A double heterostructure made of a III- V nitride semiconductor layer formed on the substrate;
A contact structure comprising a plurality of group III- V nitride semiconductor layers stacked on the double heterostructure and having p-type conductivity ;
An electrode formed on the contact structure;
The group III- V nitride semiconductor layer constituting the contact structure includes aluminum as a group III element and arsenic or phosphorus as a group V element,
The ratio of nitrogen to arsenic or phosphorus in each group III- V nitride semiconductor layer constituting the contact structure is increased stepwise from the electrode toward the double heterostructure . The substrate is made of sapphire, ZnO, LiAlO ₂ The semiconductor light-emitting device according to claim 1, wherein the semiconductor light-emitting device is made of SiC . The semiconductor light emitting element according to claim 1, wherein the substrate is made of a SiC inclined substrate . A substrate,
A first cladding layer of a first conductivity type formed on the substrate and made of a III-V group compound containing nitrogen;
An active layer formed on the first cladding layer and made of a III-V group compound containing nitrogen;
A second cladding layer of a second conductivity type formed on the active layer and made of a group III-V compound containing nitrogen;
A contact layer of a second conductivity type formed on the second cladding layer and made of a group III-V compound containing phosphorus and nitrogen or arsenic and nitrogen;
An electrode formed on the contact layer ,
A semiconductor light emitting element , further comprising a semiconductor layer made of AlN formed between the contact layer and the second cladding layer .

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