JP2002100830A - Gallium nitride light-emitting element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a gallium nitride light-emitting element in high slope efficiency and high-reliability with its life prolonged by suppressing a braking of the end surface of the light-emitting element during the high-output operation of the light-emitting element. SOLUTION: A gallium nitride light-emitting element is formed in a structure that more than one layer of low reflective films having refractive indexes lower than that of a gallium nitride are laminated on a light emitting side mirror surface, in such a way that the refractive indexes become lower in order from the light emitting side mirror surface, and the first low reflective film directly over the mirror surface is formed of one kind of a material of either selected from among a ZrO2, an MgO, an Al2O3, an Si3N4, an AlN and an MgF2. Moreover, a protective film consisting of one kind of a material of either selected from among a ZrO2, an MgO, an Si3N4, an AlN and an MgF2 is formed on the mirror surface and a high reflective film formed by alternately laminating low-refractive index-layers and high-refractive index layers is formed on the protective film.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a high power and highly reliable gallium nitride based light emitting device used for a light emitting diode or a laser diode.

[0002]

2. Description of the Related Art FIG. 5 is a schematic perspective view showing the structure of a conventional nitride semiconductor light emitting device. This light emitting device 100
Are formed on a sapphire substrate 101 on a buffer layer 102, an n-type contact layer 103, a crack prevention layer 104, an n-type cladding layer 105, an n-type guide layer 106, an active layer 107,
A mold cap layer 108, a p-type guide layer 109, a p-type clad layer 110, and a p-type contact layer 111, which are sequentially laminated,
A stripe-shaped light emitting layer is formed by dry etching, and then a p-side electrode 112 and an n-side electrode 113 are formed. Further, after forming a cleaved surface with a predetermined cavity length, a laminated film 1 of SiO ₂ and TiO ₂ is formed on the mirror surface on the light reflection side.
A high reflection film 120 in which a plurality of layers 21 are laminated is formed so that oscillation light can be efficiently extracted from the mirror surface on the light emission side.

[0003]

However, when operated at a high output, for example, 30 mW or more, there is a problem that the end face is easily broken on the mirror surface on the light reflection side, and the life is shortened. Further, when operating at a high output, there is a problem that if the slope efficiency is low, the drive current increases.

Accordingly, an object of the present invention is to provide a highly reliable nitride semiconductor light emitting device which has a high slope efficiency and a high slope efficiency, while suppressing end surface breakdown during high power operation.

[0005]

To solve the above problems, the present invention provides a gallium nitride light emitting device having a resonator structure having a light emitting side mirror surface and a light reflecting side mirror surface at both end surfaces of a stripe-shaped light emitting layer. In the light-emitting side mirror surface, two or more low-reflection films having a lower refractive index than gallium nitride are stacked so that the refractive index decreases in order from the light-emitting side mirror surface, and immediately above the light-emitting side mirror surface The first low reflection film is made of ZrO
₂ , MgO, Al ₂ O ₃ , Si ₃ N ₄ , AlN, and M
characterized in that it consists of any one selected from gF _2.

In the gallium nitride-based light emitting device of the present invention, two or more low-reflection films having a refractive index lower than that of gallium nitride are formed on the light emitting side mirror surface such that the refractive index decreases in order from the light emitting side mirror surface. Since the layers are stacked, the reflection of the oscillating light is suppressed and the ratio of the oscillating light extracted from the light-emitting side mirror surface can be increased as compared with the case where the oscillating light is directly extracted into the air from the light-emitting side mirror surface. Also, ZrO ₂ , MgO, Al _{2 is formed on} the first low-reflection film immediately above the light-exit-side mirror surface.
By using one of O ₃ , Si ₃ N ₄ , AlN, and MgF ₂ , deterioration of the mirror surface on the light emitting side due to the reaction between gallium nitride and the low reflection film during operation is suppressed. Therefore, the life of the light emitting element is improved.

Further, in the gallium nitride based light emitting device of the present invention, the first low reflection film is made of ZrO ₂ , Si ₃ N ₄ and A
1N, and SiO ₂ , Al ₂ O ₃ , MgO, and MgF are formed on the first low-reflection film.
_A film formed with a second low-reflection film made of any one of the materials selected from No. 2 can be used.

Further, in the gallium nitride-based light emitting device of the present invention, a single low-reflection film having a lower refractive index than gallium nitride is formed on the light-emitting-side mirror surface, and the low-reflection film is made of MgO,
One composed of any one selected from Al ₂ O ₃ and MgF ₂ can be used.

Further, in the gallium nitride based light emitting device of the present invention, ZrO ₂ , MgO, Si ₃ N ₄ ,
A protective film made of any one selected from AlN and MgF ₂ is formed, and a high reflective film formed by alternately laminating a low refractive index layer and a high refractive index layer on the protective film. What is formed can be used.

Further, the gallium nitride based light emitting device of the present invention is a gallium nitride based light emitting device having a resonator structure having a light emitting side mirror surface and a light reflecting side mirror surface on both end surfaces of a stripe-shaped light emitting layer. On the side mirror surface, two or more low-reflection films having a refractive index lower than that of gallium nitride are stacked so that the refractive index decreases in order from the light emission side mirror surface, and a first reflection layer directly above the light emission side mirror surface. The low reflection film is made of ZrO ₂ , Mg
O, Al ₂ O ₃ , Si ₃ N ₄ , AlN, and MgF _2.
A protective film made of any one selected from rO ₂ , MgO, Si ₃ N ₄ , AlN and MgF ₂ is formed, and a low refractive index layer and a high refractive index layer are alternately formed on the protective film. A high-reflection film formed by laminating the layers.

Further, in the gallium nitride-based light emitting device of the present invention, the low refractive index layer and the high refractive index layer may be made of SiO ₂ and ZrO ₂ , respectively.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described with reference to the drawings. However, the gallium nitride-based light emitting device of the present invention is not limited to the device structure and electrode configuration shown in the embodiment.

Embodiment 1 FIG. Embodiment 1 relates to a gallium nitride-based light emitting device using a nitride semiconductor substrate as a substrate. 1 and 2 show Embodiment 1 of the present invention.
FIG. 1 is a perspective view, and FIG. 2 is a cross-sectional view showing a cross-sectional structure taken along line II-II ′ of FIG. As shown in FIG. 1, the light-emitting element 1 has a multilayer low-reflection film 80 including a first low-reflection film 81 and a second low-reflection film 82 on a light-exiting-side mirror surface, and a light-reflecting-side mirror surface on a light-reflecting side mirror surface. The protective film 90 includes a high reflective film 91 in which a plurality of laminated films 92 of a low refractive index layer and a high refractive index layer are laminated.

Further, as shown in FIG. 2, the light emitting device 1 has a nitride semiconductor substrate 11 made of GaN, and an n-type contact layer 1 made of n-type GaN is formed on the substrate 11.
2 are formed. A crack prevention layer 13 made of n-type InGaN is formed on the n-type contact layer 12, and an n-type AlGa
An n-type cladding layer 14 made of N / GaN and an n-type guide layer 15 made of n-type GaN are formed. On the n-type guide layer 15, an InGaN / I of a multiple quantum well structure
An active layer 16 made of nGaN is formed, and a p-type cap layer 17 made of p-type AlGaN is formed on the active layer 16. On the p-type cap layer 17, a p-type G
A p-type guide layer 18 made of aN is formed, and a p-type clad layer 19 made of p-type AlGaN / GaN is formed thereon.
Then, a p-type contact layer 20 made of p-type GaN is formed. The p-type contact layer 20 has p
The side electrode 23 has an n-side electrode 22 formed on the n-type contact layer 12.

In the first embodiment, by using a substrate made of a nitride semiconductor, dislocation of a nitride semiconductor grown thereon can be suppressed and crystallinity can be improved. Can be further improved.

Here, the substrate made of a nitride semiconductor can be formed, for example, by a method of growing a nitride semiconductor having good crystallinity described in Japanese Patent Application Laid-Open No. 11-191659 (hereinafter referred to as ELOG).
(Epitaxially laterally overgrown GaN) growth method. ). In other words, the C plane is the main surface, and the orientation flat (orientation flat)
A buffer layer made of GaN is grown on a sapphire substrate having a plane A. After the growth of the buffer layer, a first nitride semiconductor layer made of undoped GaN is grown.
Next, a striped photomask is formed, a patterned SiO ₂ film is formed by a sputtering device, and then the first nitride semiconductor in a portion where the SiO ₂ film is not formed is formed by a RIE device on a sapphire substrate. The first nitride semiconductor is exposed on the side surfaces of the concave portions by etching until the surface is exposed to form irregularities. Next, the SiO ₂ above the protrusion is removed. Next, Ga doped with Si
A second nitride semiconductor layer made of N is grown. next,
The wafer on which the second nitride semiconductor layer has been grown is taken out of the reaction vessel, and the sapphire substrate, the buffer layer, the first nitride semiconductor layer, and the SiO ₂ film are polished and removed to form a second nitride semiconductor layer. Obtain a substrate consisting of only

The low reflection film formed on the mirror surface on the light emitting surface side includes:
A material having a lower refractive index than GaN (refractive index 2.3), a high melting point and excellent thermal stability, and more preferably a material having no absorption in the oscillation wavelength region of the light emitting element can be used. . As a material satisfying these conditions, for example,
ZrO ₂ (refractive index 2.1), MgO (refractive index 1.7),
Al ₂ O ₃ (refractive index 1.54), Si ₃ N ₄ (refractive index 2.0), AlN (refractive index 2.0), and MgF ₂
(Refractive index: 1.4).

Here, it is preferable that the low reflection film formed on the mirror surface on the light emitting surface side be a multilayer of two or more layers. This low-reflection film can suppress the reflection of light on the light-emitting-surface-side mirror surface, and becomes an anti-reflection film.

It is desirable that the low reflection film is laminated such that the refractive index becomes lower in order from the mirror surface on the light exit surface side. Further, the first low-reflection film immediately above the light-emitting-surface-side mirror surface can be made of any one material of ZrO ₂ , Si ₃ N ₄ , and AlN, but Zr having excellent thermal stability.
O ₂ is preferred. The second low reflection layer is made of SiO ₂ ,
Any one of Al ₂ O ₃ , MgO, and MgF ₂ can be used. The low-reflection film may be formed as a single layer. In the case of a single layer, MgO, Al ₂ O ₃ ,
It is preferable to use any one of MgF ₂ and MgF ₂ .

The low reflection film is formed by vapor deposition, sputtering, CV
It can be formed using a vapor deposition technique such as D. The oscillation wavelength is λ, and the refractive index of the low reflection film is n.
Then, it is desirable to set it to λ / 4n. When two or more low-reflection films are used, the thickness of the first low-reflection film is λ
/ 2n.

Further, a material having a high melting point and excellent thermal stability can be used for the protective film formed on the mirror surface on the light reflection side. For example, ZrO ₂ , MgO, Si ₃ N ₄ , Al
N, and MgF ₂ can be mentioned, but it is desirable to use ZrO ₂ . By providing this film, it is possible to prevent the end face from deteriorating between GaN and SiO ₂ in the conventional structure.

The protective film is formed by vapor deposition, sputtering, CVD
And the like. Assuming that the oscillation wavelength is λ and the refractive index of the protective film is n, the thickness of the protective film is desirably λ / 4n or λ / 2n.

On the protective film, a high-reflection film in which low-refractive-index layers and high-refractive-index layers are alternately laminated is formed. For the high reflection film, a material used for a conventional laser diode or the like can be used. For example, as a combination of (low refractive index layer: high refractive index layer), (SiO ₂ : ZrO ₂ ) or ( It is most preferable to use SiO ₂ : TiO ₂ ) or the like, but it is only necessary to select a combination of a material having a relatively low refractive index and a material having a relatively high refractive index.

When a protective film is provided for the low refractive index layer and the high refractive index layer, it is preferable to form two to five pairs of high reflection films, which are alternately and repeatedly laminated. More preferably, it is 3 pairs or 4 pairs, and most preferably, 3 pairs. By doing so, the life of the light emitting element can be further improved with high output.

As a method of forming the low-reflection film and the high-reflection film on the light-exiting side and the light-reflecting side mirror surface, the wafer is cleaved or cut in a bar shape in a direction perpendicular to the stripes of each light emitting layer. It is preferable that the bar is formed in a state where the bar is tilted by 90 degrees. This takes into account the characteristics of the vapor phase growth apparatus used for film formation, such as vapor deposition and sputtering, and is formed by setting the film forming surface in the film growth direction to face the vapor deposition source and the sputtering target. By doing so, a low-reflection film and a high-reflection film having a uniform film thickness can be obtained. Further, the wraparound effect in the vapor phase growth allows the bar to be formed without tilting the bar by 90 degrees, but the uniformity of the film thickness is inferior to that of the film formed by tilting. When the cavity surface on the light emission side and the light reflection side is a surface formed by opening the cleft, the bar is tilted 90 degrees,
When the resonator surface is a surface formed by etching, it is preferable to form the film using the wraparound without falling down by 90 degrees.

Embodiment 2 FIG. Embodiment 2 relates to a gallium nitride-based light emitting device using a heterogeneous substrate having a nitride semiconductor layer formed by an ELOG growth method as a substrate. 3 and 4 are schematic diagrams showing the structure of the gallium nitride-based light emitting device according to the second embodiment. 3 is a perspective view, and FIG. 4 is a cross-sectional view showing a cross-sectional structure taken along line IV-IV ′ of FIG. As shown in FIG. 3, this light emitting element has a first low reflection film 81 and a second low reflection film 82 on the light emitting side mirror surface.
And a protective film 90 on the light-reflecting side mirror surface, and a high-reflection film 91 formed by laminating a plurality of laminated films 92 of a low-refractive-index layer and a high-refractive-index layer. .

Further, as shown in FIG. 4, the light emitting device 1 has a sapphire substrate 31 on which a G
A buffer layer 32 made of aN is formed. On this buffer layer 32, undoped GaN serving as an underlayer is provided.
Layers 33 and 34 are formed. Undoped GaN layer 3
4, an n-type contact layer 35 made of n-type GaN
Is formed thereon, and a crack prevention layer 36 made of n-type InGaN is formed thereon. On the crack preventing layer 36, an n-type cladding layer 37 made of n-type GaN, on which an n-type guide layer 38 made of undoped GaN,
On top of this, an n-type InGaN / InG having a multiple quantum well structure
An active layer 39 made of aN is formed. Active layer 39
A p-type cap layer 40 made of p-type AlGaN is
Is formed thereon, and a p-type guide layer 41 made of undoped GaN is formed thereon, and a p-type AlGa
A p-type cladding layer 42 made of N / GaN is formed,
On the mold cladding layer 42, a p-type contact layer 43 made of p-type GaN is formed. p-type contact layer 4
3 on the p-side electrode 50 through the opening of the first insulating film 60.
However, a pad electrode 70 is further formed through an opening of the second insulating film 61.

A heterogeneous substrate having a nitride semiconductor layer formed by the ELOG growth method is disclosed in, for example, JP-A-11-1916.
It can be produced using the method described in JP-A-59-59. That is, a buffer layer made of GaN is grown on a sapphire substrate having a C plane as a main plane and an orientation flat (orientation flat) plane as an A plane. After the growth of the buffer layer, a first nitride semiconductor layer made of undoped GaN is grown. Next, a striped photomask is formed, and S
An iO ₂ film is formed, and then SiO ₂ film is formed by an RIE apparatus.
The first nitride semiconductor in the portion where the film is not formed is etched until the sapphire substrate is exposed to form irregularities, thereby exposing the first nitride semiconductor on the side surface of the concave portion. Next, the SiO ₂ above the protrusion is removed. next,
It can be manufactured by growing a second nitride semiconductor layer made of GaN doped with Si.

As a substrate on which a nitride semiconductor is grown,
In addition to sapphire (main surface is C-plane, R-plane, A-plane), SiC,
ZnO, spinel (MgAl ₂ O ₄ ), GaAs, Si
A different substrate made of a material different from a nitride semiconductor, such as C (including 6H, 4H, and 3C), which is conventionally known for growing a nitride semiconductor can be used.

In the second embodiment, a low-reflection film can be formed on the light-exiting-side mirror surface and a protective film can be formed on the light-reflecting surface side in the same manner as in the first embodiment. Similar effects can be obtained.

In the first and second embodiments, examples are shown in which different substrates such as sapphire and the like having a nitride semiconductor substrate and a nitride semiconductor layer formed by ELOG growth are used as the substrates. Needless to say, even when a heterogeneous substrate having no nitride semiconductor layer formed by the ELOG growth method is used, the same effects as those of the first and second embodiments can be obtained.

As a method of forming the low reflection film and the high reflection film on the light emitting side and the light reflection side mirror surface in the second embodiment, it is possible to form the same method as in the first embodiment. Since the substrate is hardly cleaved and difficult to form in a bar shape, it can be formed as follows in addition to the method of the first embodiment.

After growing the p-type contact layer and lowering the resistance, the surface of the n-type contact layer is exposed by etching. At this time, the light emitting side and the light reflecting side resonator surfaces are also formed by etching. That is, the light emitting side mirror surface and the light reflecting side mirror surface are obtained by the etching. Next, a low-reflection film and a high-reflection film are formed by a vapor phase epitaxy apparatus using the wraparound of the light-emitting-side mirror surface and the light-reflecting-side mirror surface obtained by etching.

Further, as a more preferable forming method, n
After exposing the mold surface by etching and obtaining the mirror surface on the light emission side and the mirror surface on the light reflection side at the same time, the nitride semiconductor layer around the device is further etched until the sapphire is exposed so that the device can be easily formed into chips to form grooves. I do. At this time, etching is performed at least on the light emission side and further on the light reflection side at a position where the emitted light is not blocked so that the emitted laser light has a good far-field pattern. Next, a low-reflection film and a high-reflection film are formed by a vapor phase epitaxy apparatus using the wraparound on the light-emitting side mirror surface and the light-reflecting side mirror surface. By forming in this manner, it is possible to avoid non-uniformity of the thickness of the low-reflection film and the high-reflection film due to the mask when etching is performed using the mask, and to easily form a chip at a position etched to sapphire. This is preferable because it can be converted into a compound.

[0035]

EXAMPLE 1 In Example 1, a sapphire substrate having a nitride semiconductor layer grown by ELOG on the substrate was used.
Then, a nitride semiconductor substrate was used as the substrate.

Embodiment 1 Example 1 will be described with reference to FIG. (0001) Sapphire substrate having C-plane as a main surface A substrate 31 made of sapphire is set in a MOVPE reaction vessel, the temperature is set to 500 ° C., and trimethylgallium (T
The buffer layer 32 made of GaN was grown to a thickness of 200 ° using MG) and ammonia (NH ₃ ).

Next, after the growth of the buffer layer, only TMG was stopped, and the temperature was raised to 1050 ° C. When the temperature reached 1050 ° C., an undoped GaN layer 33 was grown to a thickness of 2 μm using TMG and ammonia as source gases. Thereafter, a stripe-shaped photomask is formed, and a stripe width (a part to be an upper part of the projection) of 5 μm is formed by a sputtering apparatus.
m, stripe interval (part to be the bottom of concave portion) 10 μm
To form a patterned SiO ₂ film.
The undoped GaN layer 33 in the portion where the SiO ₂ film is not formed is etched by the IE apparatus until the substrate 31 is exposed to form irregularities. SiO ₂
Was removed. Next, it is set in a reaction vessel, and undoped GaN is used at normal pressure using TMG and ammonia as source gases.
Layer 34 was grown to a thickness of 2 μm. Undoped GaN
The underlayer consisting of the layer 33 and the undoped GaN layer 34
It acts as a substrate in the growth of each layer forming the element structure.

Next, at a temperature of 1050 ° C., T
Using MG and ammonia, silane gas (S
Using iH ₄ ), an n-type contact layer 35 made of GaN doped with 3 × 10 ¹⁸ / cm ^{3 of} Si was grown to a thickness of 4 μm.

Next, the temperature was raised to 800 ° C.
TMG, TMI (trimethylindium) and ammonium
Using silane gas as the impurity gas,
10 ¹⁸/ Cm³Doped In_0.06Ga_0.94
A crack preventing layer 36 made of N is formed to a thickness of 0.15 μm.
Lengthened.

Next, the temperature was raised to 1050 ° C., and TMA (trimethylaluminum), TMG and ammonia were used as source gases, and undoped Al _0.14 Ga _0.86 was used.
N is grown to a thickness of 25 °, followed by stopping TMA,
Using silane gas as impurity gas, Si
GaN doped at ¹⁹ / cm ³ was grown to a thickness of 25 °. This operation is alternately repeated to obtain a total film thickness of 1.2 μm.
The n-type cladding layer 37 having the superlattice structure was grown.

Next, at a temperature of 1050 ° C.,
G, n made of undoped GaN using ammonia
The mold guide layer 38 was grown to a thickness of 0.2 μm.

Next, the temperature is set to 800 ° C., and T
MG, TMI and ammonia
5 × 10¹⁸/ Cm³Doped
In _0.05Ga_0.95N barrier layer (B layer)
It was grown to a thickness of 100 °. Next, stop the silane gas.
Undoped In_0.2Ga_0.8Well made of N
A layer (W layer) is grown to a thickness of 40 °. Barrier layers and wells
Layers are laminated in the order of B layer-W layer-B layer-W layer-B layer,
Growing active layer 39 with multiple quantum well structure with total thickness of 380 °
I let it.

Next, at a temperature of 800.degree.
A, TMG and ammonia, and C as impurity gas
Al _0.3 doped with 1 × 10 ²⁰ / cm ^{3 of} Mg using p ₂ Mg (cyclopentadienyl magnesium)
A p-type cap layer 40 of Ga _0.7 N was grown to a thickness of 300 °.

Next, at a temperature of 1050 ° C., a p-type guide layer 41 of undoped GaN was grown to a thickness of 0.1 μm using TMG and ammonia as source gases. Although this p-type guide layer was grown as undoped, the diffusion of Mg from the p-type cap layer 40
The concentration becomes 1 × 10 ¹⁸ / cm ³ , indicating p-type.

Next, at a temperature of 1050 ° C.,
A, TMG and ammonia, undoped Al
_0.1 Ga _0.9 N is grown to a film thickness of 25 °, then TMA is stopped, Cp ₂ Mg is used as an impurity gas, and GaN doped with 1 × 10 ²⁰ / cm ^{3 of} Mg is used.
It was grown to a thickness of 5 °. This operation was alternately repeated to grow a p-type cladding layer 42 having a superlattice structure with a total film thickness of 0.6 μm.

Next, at a temperature of 1050 ° C.,
Using G, ammonia, and Cp ₂ Mg as an impurity gas, a p-type contact layer 43 made of GaN doped with Mg at 1 × 10 ²⁰ / cm ³ was grown to a thickness of 25 °.

After the completion of the reaction, the wafer was annealed in a nitrogen atmosphere at 700 ° C. in a reaction vessel to further reduce the resistance of the p-type layer.

The nitride semiconductor is grown as described above.
The removed wafer is taken out of the reaction vessel and the n-type contact layer 3 is removed.
5 is exposed on a part of the p-type contact layer 43 to expose
iO ₂Form a mask, RIE (Reactive Ion Etching
Etching), and the surface of the n-type contact layer 35 is etched.
The surface was exposed.

Further, a p-type nitride semiconductor layer having a width of 1.5 μm is formed on the surface of the uppermost p-type contact layer 43 and the entire surface of the exposed n-type contact layer 35 via a mask having a predetermined shape. An SiO ₂ mask composed of stripes was formed. After forming the SiO ₂ mask, etching was performed to the vicinity of the interface between the p-type cladding layer 42 and the p-type guide layer 41 using RIE, thereby forming a 1.5 μm-wide striped waveguide (ridge).

After the formation of the ridge, a first layer made of ZrO ₂ is formed on the surface of the p-type nitride semiconductor layer while keeping the SiO ₂ mask.
Was formed. The first insulating film 60 may be formed on the entire surface of the nitride semiconductor layer by first masking the surface on which the n-side electrode 51 is formed. After the first insulating film formed is immersed in buffered hydrofluoric acid, a SiO ₂ mask formed on the p-type contact layer 43 dissolve and remove, with SiO ₂ by lift-off, the p-type contact layer 43 (more n ZrO on the mold contact layer 35)
₂ was removed. This ZrO ₂ can be formed in one step as the low reflection film on the light emission side mirror surface and the protective film on the light reflection side mirror surface of the present invention.

Next, a p-side electrode 50 made of Ni / Au was formed in a stripe shape in contact with the outermost surface of the ridge on the p-type contact layer 43 and the first insulating film 60. On the other hand, an n-side electrode 51 made of Ti / Al was formed in a stripe shape on the surface of the n-type contact layer 35 (and in contact with the first insulating film 60). After these were formed, they were annealed at a ratio of oxygen: nitrogen of 80:20 at 600 ° C. to alloy the p-side electrode 50 and the n-side electrode 51, thereby obtaining good ohmic characteristics.

Next, a second insulating film 61 made of SiO ₂
Was formed on the entire surface, a resist was applied to the entire surface except for a part of the p-side electrode 50 and the n-side electrode, and dry etching was performed, thereby exposing a part of the p-side electrode 50 and the n-side electrode 51.
This SiO ₂ can be formed in a single step as a part of the low reflection film on the light exit side mirror surface and the high reflection film on the light reflection side mirror surface of the present invention.

After forming the second insulating film 61, the pad electrode 70
The p-side is the second insulating film 61 on the p-type nitride semiconductor layer
In one step, an adhesion layer made of Ni was formed to a thickness of 1000 ° so as to cover the p-side electrode 50 and to cover a part of the second insulating film 61 and the n-side electrode 51 on the n-side. Further, a barrier layer made of Ti is formed on the adhesion layer by 1000Å.
Then, Au was formed to a thickness of 8000 °.

After the sapphire substrate of the wafer on which the p-side electrode and the n-side electrode are formed is polished to 70 μm, the wafer is opened in a bar shape from the substrate side in a direction perpendicular to the stripe-shaped electrodes. The resonator was formed on the (11-00 plane, the plane corresponding to the side surface of the hexagonal columnar crystal = M plane). This resonator may be formed by etching.

Next, a first low-reflection film made of ZrO ₂ and SiO ₂ were formed on the light-emitting side mirror surface of the resonator by using a sputtering apparatus.
₂ was formed. Here, the thickness of each of the first low-reflection film and the second low-reflection film is 470.
And 690 °. On the other hand, a protective film made of ZrO ₂ was formed on the light reflection side mirror surface by using a sputtering apparatus, and then three pairs of SiO ₂ and ZrO ₂ were alternately laminated to form a high reflection film. Here, the thicknesses of the protective film, the SiO ₂ film and the ZrO ₂ film constituting the high reflection film are each 470.
Å, 690Å and 470Å. Finally, the bar was cut in a direction parallel to the p-side electrode to obtain a laser device.

The obtained laser device was placed on a heat sink, and the respective electrodes were wire-bonded, and laser oscillation was attempted at room temperature. As a result, continuous oscillation at an oscillation wavelength of 400 nm was confirmed at room temperature with a threshold value of 2.2 kA / cm ² and a threshold voltage of 4.2 V, and the lifetime was 1.8 times longer than that of the conventional device of the comparative example. Improved. Although the threshold value was slightly higher than that of the related art, the slope efficiency indicating the slope of the current-output characteristic was improved by 30% as compared with the related art. From these results, this light emitting device is useful for a high power laser device.

Embodiment 2 Embodiment 2 will be described with reference to FIG. In Example 1, the sapphire substrate and the buffer layer were polished and removed from the sapphire substrate on which the underlayer was formed, leaving only the undoped GaN layer. However, the film thickness when growing the undoped GaN layer 34 was 80 μm.

Next, at a temperature of 1050 ° C., T
An n-type contact layer 12 made of GaN doped with Si at 3 × 10 ¹⁸ / cm ³ was grown to a thickness of 3 μm using MG and ammonia and silane gas as an impurity gas.

Next, the temperature was raised to 800 ° C.
TMG, TMI (trimethylindium) and ammonium
Using silane gas as the impurity gas,
10 ¹⁸/ Cm³Doped In_0.14Ga_0.86
A crack prevention layer 13 made of N is grown to a thickness of 0.1 μm.
I let it.

Next, the inside of the reaction vessel was set to a hydrogen atmosphere, the temperature was set to 1050 ° C., and TMA, TMG and ammonia were used as source gases, and undoped Al _0.14 Ga
_0.86 N is grown to a thickness of 25 ° followed by TMA
Is stopped, silane gas is used as an impurity gas, and
GaN doped with × 10 ¹⁹ / cm ³ was grown to a thickness of 25 °. This operation is alternately repeated 240 times to obtain an n-type clad layer 1 having a superlattice structure with a total film thickness of 1.2 μm.
4 grew.

Next, at a temperature of 1050 ° C.,
G, n made of undoped GaN using ammonia
The mold guide layer 15 was grown to a thickness of 0.1 μm.

Next, the temperature is set to 800 ° C., and T
MG, TMI and ammonia
5 × 10¹⁸/ Cm³Doped
In _0.02Ga_0.98The barrier layer made of N
It was grown to a film thickness. Subsequently, Si-doped In_0.15
Ga_0.85A well layer of N is grown to a thickness of 20 °.
I let you. This operation is repeated four times, and finally, a barrier layer is laminated.
The active layer 16 having a multiple quantum well structure with a total thickness of 330 ° is formed.
Lengthened.

Next, at a temperature of 800.degree.
A, TMG and ammonia, and C as impurity gas
Al _0.2 doped with 1 × 10 ²⁰ / cm ^{3 of} Mg using p ₂ Mg (cyclopentadienyl magnesium)
A p-type cap layer 17 of Ga _0.8 N was grown to a thickness of 200 °.

Next, at a temperature of 1050 ° C., a p-type guide layer 18 of undoped GaN was grown to a thickness of 0.1 μm using TMG and ammonia as source gases. Although this p-type guide layer was grown as undoped, Mg was diffused from the p-type cap layer 17 so that Mg
The concentration becomes 1 × 10 ¹⁸ / cm ³ , indicating p-type.

Next, at a temperature of 1050 ° C.,
Undoped Al using A, TMG and ammonia
_0.14Ga_0.86N is grown to a thickness of 25 °
And stop TMA and use Cp as impurity gas.₂Use Mg
And Mg is 1 × 10²⁰/ Cm ³Doped GaN 2
It was grown to a thickness of 5 °. Repeat this operation alternately
And a p-type crack having a superlattice structure having a total film thickness of 0.6 μm.
A layer 19 was grown.

Next, at a temperature of 1050 ° C.,
Using G, ammonia, and Cp ₂ Mg as an impurity gas, a p-type contact layer 20 of GaN doped with Mg at 1 × 10 ²⁰ / cm ³ was grown to a thickness of 0.05 μm.

After the completion of the reaction, the wafer was annealed at 700 ° C. in a nitrogen atmosphere in a reaction vessel to further reduce the resistance of the p-type layer.

The nitride semiconductor is grown as described above.
The removed wafer is taken out of the reaction vessel and the n-type contact layer 1 is removed.
2 is exposed to expose a part of the p-type contact layer 20.
iO ₂Form a mask, etch by RIE,
The surface of the n-type contact layer 12 was exposed.

Further, a p-type nitride semiconductor layer having a width of 1.5 μm is formed on the surface of the uppermost p-type contact layer 20 and the entire surface of the exposed n-type contact layer 12 through a mask having a predetermined shape. An SiO ₂ mask composed of stripes was formed. After forming the SiO ₂ mask, etching was performed to the vicinity of the interface between the p-type cladding layer 19 and the p-type guide layer 18 using RIE, thereby forming a 1.5 μm-wide stripe-shaped waveguide (ridge).

Next, a p-side electrode 23 made of Ni / Au was formed in a stripe shape on the outermost surface of the ridge on the p-type contact layer 20. On the other hand, the surface on the n-type contact layer 35 has T
An n-side electrode 22 made of i / Al was formed in a stripe shape. After these are formed, each of them is oxygen: nitrogen 80: 2
Annealing at 600 ° C. at a rate of 0
And the n-side electrode 22 were alloyed to obtain good ohmic characteristics.

Next, an insulating film 21 made of SiO ₂ is formed on the entire surface, a resist is applied to the entire surface except for a part of the p-side electrode 23 and the n-side electrode 22, and dry etching is performed. 23 and the n-side electrode 22 were exposed.
This SiO ₂ can be formed in one step as a part of the low-reflection film on the light-emitting side mirror surface and the high-reflection film on the light reflection side mirror surface of the present invention.

After the sapphire substrate of the wafer on which the p-side electrode and the n-side electrode were formed was polished to 70 μm, the wafer was opened in a bar shape from the substrate side in a direction perpendicular to the stripe-shaped electrodes. The resonator was formed on the (11-00 plane, the plane corresponding to the side surface of the hexagonal columnar crystal = M plane). This resonator may be formed by etching.

Next, a first low-reflection film made of ZrO ₂ and SiO ₂ were formed on the light-emitting side mirror surface of the resonator by using a sputtering apparatus.
₂ was formed. Here, the thickness of each of the first low-reflection film and the second low-reflection film is 470.
And 690 °. On the other hand, a protective film made of ZrO ₂ was formed on the light reflection side mirror surface by using a sputtering apparatus, and then three pairs of SiO ₂ and ZrO ₂ were alternately laminated to form a high reflection film. Here, the thicknesses of the protective film, the SiO ₂ film and the ZrO ₂ film constituting the high reflection film are each 470.
Å, 690Å and 470Å. Finally, the bar was cut in a direction parallel to the p-side electrode to obtain a laser device.

The obtained laser element was placed on a heat sink, and the respective electrodes were wire-bonded, and laser oscillation was attempted at room temperature. As a result, continuous oscillation at an oscillation wavelength of 400 nm was confirmed at room temperature with a threshold value of 2.2 kA / cm ² and a threshold voltage of 4.2 V, and the lifetime was 2.0 times that of the conventional device of the comparative example. Improved. Although the threshold value was slightly higher than the conventional one, the slope efficiency was improved by 30% compared to the conventional one. From these results, this light emitting device is useful for a high power laser device.

Embodiment 3 FIG. As shown in FIG. 1, a sapphire substrate having a C-plane as a main surface and an orientation flat surface as an A-plane was used as a substrate, and was set in a MOCVD apparatus.
Thermal cleaning was performed for 0 minutes to remove moisture and attached substances on the surface. Then, the temperature was raised to 510 ° C., and a buffer layer made of GaN was grown to a thickness of 200 Å using hydrogen as a carrier gas and ammonia and trimethylgallium as source gases. Thereafter, an undoped GaN layer was formed at 1050 ° C. with a thickness of 20 μm.

Then, it is set in a hydride vapor phase epitaxy (HVPE) apparatus, Ga metal is prepared in a quartz boat, GaCl ₃ is generated by using HCl gas as a halogen gas, and then ammonia gas is used as an N gas source. And a second G of undoped GaN
An aN layer was grown to a thickness of 200 μm.

Next, the procedure is the same as that of the first embodiment until the formation of the uppermost p-type contact layer 43 from the n-type nitride semiconductor layer 35 made of Si doping.

After forming up to the p-type contact layer 43 and lowering the resistance, etching is performed so that the surface of the n-type contact layer is exposed, and at the same time, the light emission side and the light reflection side resonator surfaces are formed.

Further, a p-type nitride semiconductor layer having a width of 1. is formed on the surface of the uppermost p-type contact layer 43 and the entire surface of the exposed n-type contact layer 35 via a mask having a predetermined shape.
An SiO ₂ mask consisting of a 5 μm stripe was formed. After forming the SiO ₂ mask, etching was performed to the vicinity of the interface between the p-type cladding layer 42 and the p-type guide layer 41 using RIE, thereby forming a 1.5 μm-wide striped waveguide (ridge).

After the formation of the ridge, an SiO ₂ mask is further formed on the light emitting surface with the SiO ₂ mask attached. Further, a first layer made of ZrO ₂ is formed on the surface of the p-type nitride semiconductor layer.
Was formed. The first insulating film 60 may be formed on the entire surface of the nitride semiconductor layer by first masking the surface on which the n-side electrode 51 is formed. After the first insulating film formed is immersed in buffered hydrofluoric acid, a SiO ₂ mask formed on the p-type contact layer 43 dissolve and remove, with SiO ₂ by lift-off, the p-type contact layer 43 (more n ZrO on the mold contact layer 35)
₂ was removed. This ZrO ₂ is also formed as a protective film on the light reflection side mirror surface.

Next, a p-side electrode 50 made of Ni / Au was formed in a stripe shape in contact with the outermost surface of the ridge on the p-type contact layer 43 and the first insulating film 60.

On the other hand, on the surface on the n-type contact layer 35 (and the surface of the first insulating film 60), an n-side electrode 51 made of Ti / Al was formed in a stripe shape.

After these are formed, oxygen: nitrogen 8
Annealing was performed at a ratio of 0:20 at 600 ° C. to alloy the p-side electrode 50 and the n-side electrode 51 to obtain good ohmic characteristics.

Next, a resist is applied to the outermost surface of the ridge and the light emitting end face, and SiO ₂ and Zr are used as the second insulating film 61.
A multilayer film of O ₂ is formed at a thickness of 690 ° and 470 °, respectively.
To form three pairs. At this time, on the light reflection surface, a multilayer film of SiO ₂ and ZrO ₂ is formed following ZrO ₂ formed in advance.

Subsequently, the resist is removed and the pad electrode 7 is removed.
On the p side, the second insulating film 6 on the p-type nitride semiconductor layer is set to 0.
The adhesion layer made of Ni and the barrier layer made of Ti are covered in one process so as to cover the first and p-side electrodes 50 and to cover a part of the second insulating film 61 and the n-side electrode 51 on the n-side. Was formed to a thickness of 1000 ° and Au was formed to a thickness of 8000 °.

Next, etching is performed at a position where the emitted light is not blocked so that the element can be easily formed into chips and the laser light emitted from the light emitting side has a good far-field pattern. In this method, first, a resist is applied to a non-etched portion as a mask (first resist). Further, on the first resist, SiO ₂ ,
Further, a second resist is formed. Subsequently, SiO ₂ is etched by RIE, and GaN in the etched portion is further etched by RIE until sapphire is exposed. Finally, it is formed by removing the first resist (lifting off the first resist).

Next, a resist is applied to the entire surface except for the laser emission surface on the emission surface side, and a first low reflection film made of ZrO ₂ and a second low reflection film made of SiO ₂ are respectively formed by 470 ° using a sputtering device. And a film thickness of 690 °, and the resist was removed.

Finally, the wafer was cut along the exposed surface of the sapphire by scribing or the like from the back surface to obtain a laser device. The characteristics of the obtained laser device were almost the same as those in Example 1.

Example 4 As shown in FIG. 1, a sapphire substrate having a C surface as a main surface and an orientation flat surface as an A surface was set in a MOCVD apparatus, and thermal cleaning was performed at a temperature of 1050 ° C. for 10 minutes. Moisture and deposits on the surface were removed.

Next, at a temperature of 510 ° C., a buffer layer made of GaN was grown to a thickness of 200 Å using hydrogen as a carrier gas and ammonia and trimethylgallium as source gases. Then, G made of undoped
An aN layer was formed at 1050 ° C. with a film thickness of 20 μm.

Next, it is set in a hydride vapor phase epitaxial growth (HVPE) apparatus, Ga metal is prepared in a quartz boat, GaCl ₃ is generated by using HCl gas as a halogen gas, and then ammonia gas is used as an N gas source. Then, a second GaN layer made of Si-doped GaN was grown to a thickness of 200 μm using dichlorosilane (SiH ₂ Cl ₂ ) gas as an impurity doping gas.

Next, the sapphire on the back surface of the obtained wafer was removed by polishing to obtain a single substrate made of Si-doped GaN. Next, the procedure is the same as that of the first embodiment until the formation of the uppermost p-type contact layer 43 from the n-type nitride semiconductor layer 35 made of Si doping. After forming up to the p-type contact layer 43 and lowering the resistance, the surface of the n-type contact layer was exposed in a stripe shape.

Further, a p-type nitride semiconductor layer having a width of 1.times. Is formed on the surface of the uppermost p-type contact layer 43 and the entire surface of the exposed n-type contact layer 35 via a mask having a predetermined shape.
An SiO ₂ mask consisting of a 5 μm stripe was formed. After forming the SiO ₂ mask, etching was performed to the vicinity of the interface between the p-type cladding layer 42 and the p-type guide layer 41 using RIE, thereby forming a 1.5 μm-wide striped waveguide (ridge).

After forming the ridge, the surface of the p-type nitride semiconductor layer is
To ZrO₂A first insulating film 60 was formed. this
The first insulating film 60 first masks the surface on which the n-side electrode 51 is to be formed.
To form a first insulating film 60 on the entire surface of the nitride semiconductor layer.
You may. After forming the first insulating film, the buffered hydrofluoric acid
SiO 2 formed on the p-type contact layer 43 by immersion ₂
The mask is dissolved and removed, and the SiO 2 is removed by a lift-off method.₂And
First, the p-type contact layer 43 (and the n-type contact
ZrO on layer 35)₂Was removed. This ZrO
₂Is also formed as a protective film on the light reflection side mirror surface.

Next, a p-side electrode 50 made of Ni / Au was formed in a stripe shape in contact with the uppermost surface of the ridge on the p-type contact layer 43 and the first insulating film 60.

On the other hand, on the surface on the n-type contact layer 35 (and the surface of the first insulating film 60), an n-side electrode 51 made of Ti / Al was formed in a stripe shape.

After these are formed, oxygen: nitrogen 8
Annealing was performed at a ratio of 0:20 at 600 ° C. to alloy the p-side electrode 50 and the n-side electrode 51 to obtain good ohmic characteristics. Next, a resist was applied to the outermost surface of the ridge, and SiO ₂ was formed as the second insulating film 61.

Subsequently, the resist is removed, and the pad electrode 7 is removed.
On the p side, the second insulating film 6 on the p-type nitride semiconductor layer is set to 0.
The adhesion layer made of Ni and the barrier layer made of Ti are covered in one process so as to cover the first and p-side electrodes 50 and to cover a part of the second insulating film 61 and the n-side electrode 51 on the n-side. Was formed to a thickness of 1000 ° and Au was formed to a thickness of 8000 °.

Next, the wafer is cleaved from the Si-doped GaN substrate side in a direction parallel to the stripe-shaped electrodes, and the cleaved surface is a cleaved surface (11-00 surface, a surface corresponding to the side surface of a hexagonal columnar crystal = M = M Surface).

Next, a first low-reflection film made of ZrO ₂ and SiO ₂ were formed on the light-emitting side mirror surface of the resonator by using a sputtering apparatus.
₂ was formed. At this time, the light emitting side mirror surface is installed so as to face the target of the sputtering apparatus. Here, the thicknesses of the first low-reflection film and the second low-reflection film are 470 ° and 690 °, respectively.

On the other hand, the light-emitting side mirror surface is set down with the light-emitting side mirror surface facing the target of the sputtering apparatus, and a protective film made of ZrO ₂ is formed on the light reflecting side mirror surface.
Next, three pairs of SiO ₂ and ZrO ₂ were alternately stacked to form a high reflection film. Here, the thicknesses of the protective film, the SiO ₂ film and the ZrO ₂ film constituting the high reflection film are each 4
70 °, 690 ° and 470 °. And finally p
The bar was cut in a direction parallel to the side electrode to obtain a laser element.

The obtained laser element was set on a heat sink, and the respective electrodes were wire-bonded, and laser oscillation was attempted at room temperature. As a result, continuous oscillation at an oscillation wavelength of 400 nm was confirmed at room temperature with a threshold value of 2.2 kA / cm ² and a threshold voltage of 4.2 V, and the lifetime was 1.8 times longer than that of the conventional device of the comparative example. Improved. Although the threshold value was slightly higher than that of the related art, the slope efficiency indicating the slope of the current-output characteristic was improved by 30% as compared with the related art. From these results, this light emitting device is useful for a high power laser device.

Example 5 As shown in FIG. 1, a sapphire substrate having a C surface as a main surface and an orientation flat surface as an A surface was set in a MOCVD apparatus, and thermal cleaning was performed at a temperature of 1050 ° C. for 10 minutes. Moisture and deposits on the surface were removed.

Next, at a temperature of 510 ° C., a buffer layer made of GaN was grown to a thickness of 200 Å using hydrogen as a carrier gas and ammonia and trimethylgallium as source gases. Then, G made of undoped
An aN layer was formed at 1050 ° C. with a thickness of 20 μm.

Next, it is set in a hydride vapor phase epitaxial growth (HVPE) apparatus, Ga metal is prepared in a quartz boat, GaCl ₃ is generated by using HCl gas as a halogen gas, and then ammonia gas as an N gas source is prepared. And a thick film undoped G
An aN layer was grown to a thickness of 200 μm.

Next, the procedure was the same as in Example 1 until the formation of the uppermost p-type contact layer 43 from the n-type nitride semiconductor layer 35 made of Si doping.

After forming up to the p-type contact layer 43 and lowering the resistance, the surface of the n-type contact layer was exposed in a stripe shape by etching. By this etching, the end face of the resonator was formed at the same time.

Further, a p-type nitride semiconductor layer having a width of 1.times. Is formed on the surface of the uppermost p-type contact layer 43 and the entire surface of the exposed n-type contact layer 35 via a mask having a predetermined shape.
An SiO ₂ mask consisting of a 5 μm stripe was formed. After forming the SiO ₂ mask, etching was performed to the vicinity of the interface between the p-type cladding layer 42 and the p-type guide layer 41 using RIE, thereby forming a 1.5 μm-wide striped waveguide (ridge).

After the formation of the ridge, the surface of the p-type nitride semiconductor layer is made of 470 ° ZrO ₂ , 690 ° SiO ₂ and Z
The first insulating film 60 was formed by laminating three pairs of combinations of rO ₂ of 470 °. This first insulating film 60
First, the first insulating film 60 may be formed on the entire surface of the nitride semiconductor layer by masking the mirror surface on the light emission side.
After the insulating film formed is immersed in buffered hydrofluoric acid, a SiO ₂ mask formed on the p-type contact layer 43 dissolve and remove, with SiO ₂ by lift-off, the p-type contact layer 43, the light-emitting side mirror Further, ZrO ₂ on the n-type contact layer 35 was removed.

Next, the first resist is patterned in accordance with the chip size of the device, and furthermore, Si is formed on the entire surface of the wafer.
A mask made of O ₂ was formed, and a second resist was patterned thereon in the same shape as the first resist. At this time, the first resist is patterned so that the exit mirror surface side is slightly outside of the exit mirror surface, and barely. Then, first, SiO ₂ is etched by RIE,
After removing SiO ₂ from the exposed surface of O _{2, the} exposed surface of the nitride semiconductor layer on which the first resist is not applied is etched until sapphire of the substrate is exposed by RIE. By this etching, the exit mirror surface is slightly outside the exit mirror surface,
Since the bare nitride semiconductor layer has been removed by etching, a good far-field pattern can be formed without emitting light hitting the nitride semiconductor layer when laser light is oscillated. Finally, by removing from the first resist, the mask of SiO ₂ and the second resist can be removed at one time.

Next, at least the mirror surface on the light emitting surface side
Resist on the resist so that only the ridge and the light emitting part are exposed.
Patterning, and using a sputtering device on it,
rO ₂And SiO₂With respect to the light emission direction, respectively.
It was formed with a film thickness of 0 ° and 690 °. Finally, the resist film
By removing, the ZrO 2₂And SiO₂But,
ZrO on light reflection end face₂And SiO₂And ZrO₂Multi-layer
Three pairs were formed.

Finally, patterning is performed in accordance with the chip size, and cut at a portion exposed to sapphire.
A laser device was used. The characteristics of the obtained laser device were almost the same as those in Example 1.

Embodiment 6 FIG. A laser device was manufactured in the same manner as in Example 2 except that the low reflection film was not formed on the light-emitting side mirror surface, and laser oscillation was attempted at room temperature. As a result, continuous oscillation at an oscillation wavelength of 400 nm was confirmed at room temperature with a threshold value of 2.2 kA / cm ² and a threshold voltage of 4.2 V, and the lifetime was 2.0 times that of the conventional device of the comparative example. Improved. From these results, this light emitting device is useful for a high power laser device.

Comparative example. A laser element was manufactured in the same manner as in Example 2, except that a low-reflection film was not formed on the light-emitting side mirror surface, and a protective film was not formed on the light-reflecting side mirror surface.
Laser oscillation was attempted at room temperature. As a result, at room temperature, the threshold voltage was 2.0 kA / cm ² and the threshold voltage was 4.0 V.
Continuous oscillation with an oscillation wavelength of 400 nm was confirmed, and the estimated lifetime was 1000 hours or more at room temperature.

[0115]

As described above, in the gallium nitride-based light emitting device of the present invention, two or more low-reflection films having a refractive index lower than that of gallium nitride are provided on the light-emitting side mirror surface from the light-emitting side mirror surface. The first low-reflection film immediately above the light-exit-side mirror surface is made of ZrO ₂ , MgO, Al ₂
Since it is formed of any one material selected from O ₃ , Si ₃ N ₄ , AlN, and MgF ₂ , the slope efficiency and the life can be improved, and a high-output and highly reliable light-emitting element is provided. it can.

In the gallium nitride-based light emitting device of the present invention, the first low reflection film is made of ZrO ₂ , Si ₃ N ₄ , and A
1N, and formed on the first low-reflection film, SiO ₂ , Al ₂ O ₃ , M
Since the second low-reflection film made of any one selected from gO and MgF ₂ is formed, the reliability of the light-emitting element can be further improved.

The gallium nitride-based light-emitting device of the present invention has a structure in which MgO, Al ₂ O ₃ , and MgF
_Since a single-layer low-reflection film made of one of the _two types is formed, a laser device with high slope efficiency can be obtained.

The gallium nitride-based light-emitting device of the present invention has a mirror-reflective surface on the light-reflecting side with ZrO ₂ , MgO, Si ₃ N ₄ ,
A protective film made of any one selected from AlN and MgF ₂ is formed, and a high reflective film is formed on the protective film by alternately stacking a low refractive index layer and a high refractive index layer. As a result, it is possible to suppress the end face destruction and improve the life at the time of high-power operation.

Further, in the gallium nitride-based light emitting device of the present invention, two or more low-reflection films having a refractive index lower than that of gallium nitride are provided on the light exit side mirror surface, and the refractive index becomes lower in order from the light exit side mirror surface. And the first low reflection film immediately above the light exit side mirror surface is made of ZrO ₂ , MgO, Al ₂ O ₃ , S
any one selected from i ₃ N ₄ , AlN and MgF ₂
Seeds, and ZrO ₂ , MgO, S
any one selected from i ₃ N ₄ , AlN and MgF ₂
A high-reflection film formed by alternately stacking a low-refractive-index layer and a high-refractive-index layer is formed on the protective film made of a seed, and a high-refractive film is formed on the protective film. Slope efficiency and life during operation can be improved.

In the gallium nitride-based light emitting device of the present invention, since the low-refractive-index layer and the high-refractive-index layer of the high-reflection layer are formed of SiO ₂ and ZrO ₂ , respectively, The output can be further improved by increasing the height.

[Brief description of the drawings]

FIG. 1 is a schematic perspective view showing a structure of a gallium nitride based light emitting device according to Embodiment 1 of the present invention.

FIG. 2 is a schematic sectional view showing the structure of the gallium nitride based light emitting device according to the first embodiment of the present invention.

FIG. 3 is a perspective view showing a structure of a gallium nitride-based light emitting device according to a second embodiment of the present invention.

FIG. 4 is a schematic sectional view showing a structure of a gallium nitride based light emitting device according to a second embodiment of the present invention.

FIG. 5 is a perspective view showing a structure of a conventional gallium nitride-based light emitting device.

[Explanation of symbols]

1,2 gallium nitride based light emitting device, 11 GaN substrate,
12,35 n-type contact layer, 13,36 crack prevention layer, 14,37 n-type cladding layer, 15,38 n-type guide layer, 16,39 active layer, 17,40 p-type cap layer, 18,41p-type guide layer , 19,42 p-type cladding layer, 20,43 p-type contact layer, 21 insulating film, 2
2,51 n-side electrode, 23,50 p-side electrode, 31 sapphire substrate, 32 buffer layer, 33,34 undoped GaN layer, 60 first insulating film, 61 second insulating film, 70 pad electrode, 80 multilayer low Reflective film, 81 first reflective film, 82 second reflective film, 90 protective film, 91
High reflection film, 92 A laminated film of a low refractive index layer and a high refractive index layer.

Claims (7)

[Claims] 1. A gallium nitride-based light emitting device having a resonator structure having a light emitting side mirror surface and a light reflecting side mirror surface at both end surfaces of a stripe-shaped light emitting layer, wherein the light emitting side mirror surface has a lower refractive index than gallium nitride. Are laminated such that the refractive index decreases in order from the mirror surface on the light emission side, and the first low reflection film immediately above the mirror surface on the light emission side is made of ZrO ₂ , MgO, Al ₂ O ₃ , Si
₃ N _4, AlN and made of any one selected from MgF ₂ gallium nitride-based light emitting device. 2. The method according to claim 1, wherein the first low reflection film is made of ZrO.₂, Si
₃N₄And any one selected from AlN,
On the first low reflection film, SiO₂, Al₂O ₃, MgO
And MgF₂The second consisting of any one selected from
2. The gallium nitride according to claim 1, wherein a low reflection film is formed.
System light emitting element. 3. A low-reflection film having a refractive index lower than that of gallium nitride is formed on the light-exiting-side mirror surface, and the low-reflection film is selected from MgO, Al ₂ O ₃ and MgF ₂ . 2. The gallium nitride-based light emitting device according to claim 1, comprising one kind. 4. A method in which ZrO ₂ , Mg is applied to the light reflecting side mirror surface.
A protective film made of any one selected from O, Si ₃ N ₄ , AlN and MgF ₂ is formed, and a low refractive index layer and a high refractive index layer are alternately laminated on the protective film. The gallium nitride-based light emitting device according to any one of claims 1 to 3, wherein a highly reflective film is formed. 5. A gallium nitride-based light emitting device having a resonator structure having a light emitting side mirror surface and a light reflecting side mirror surface at both end surfaces of a stripe-shaped light emitting layer, wherein ZrO ₂ , MgO, Si is provided on the light reflecting side mirror surface. ₃ N ₄ , Al
A protective film made of any one selected from N and MgF ₂ is formed, and a high reflective film is formed on the protective film by alternately stacking a low refractive index layer and a high refractive index layer. Gallium nitride-based light emitting device. 6. A gallium nitride-based light emitting device having a resonator structure having a light emitting side mirror surface and a light reflecting side mirror surface on both end surfaces of a stripe-shaped light emitting layer, wherein the light emitting side mirror surface has a lower refractive index than gallium nitride. Two or more low-reflection films having different refractive indices are stacked so that the refractive index decreases in order from the light-emitting side mirror surface, and a first low-reflection film immediately above the light-emitting side mirror surface is made of ZrO ₂ , MgO, Al ₂ O ₃ , S
any one selected from i ₃ N ₄ , AlN and MgF ₂
The light reflecting side mirror surface has ZrO ₂ , MgO, Si ₃ N ₄ , A
A protective film made of any one selected from 1N and MgF ₂ is formed, and a high reflective film formed by alternately laminating a low refractive index layer and a high refractive index layer on the protective film is formed. A gallium nitride-based light emitting device formed by the above method. 7. The gallium nitride based light emitting device according to claim 4, wherein the low refractive index layer and the high refractive index layer are made of SiO ₂ and ZrO ₂ , respectively.