JP2001345477A - Gallium nitride compound semiconductor light emitting element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a new structure which can improve the characteristic for distributing luminous intensity of a light emitting element using the rear surface of a substrate composed of a gallium nitride compound semiconductor on which a laminated structure containing a light emitting layer is not formed as its main light emitting surface immediately above the element, and, at the same time, can maintain the luminous intensity of the element at a high level. SOLUTION: The characteristic for distributing luminous intensity of the light emitting element immediately above the element can be made uniform by making the electrode to be arranged on the main light emitting surface unnecessary, by providing a laminated structure of an n-type clad layer 2 composed of a gallium nitride compound semiconductor, the light emitting layer 4, a p-type clad layer 6, and a p-type contact layer 7 on the substrate 1 composed of the n-type gallium nitride-based compound semiconductor, and by providing an n-side electrode in contact with the surface of the substrate 1 exposed by partially removing the substrate 1 from the surface side of the laminated structure.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a semiconductor light emitting device used for a light emitting diode, and more particularly to a gallium nitride compound light emitting device using a gallium nitride compound semiconductor substrate.

[0002]

2. Description of the Related Art Gallium nitride compound semiconductors have been widely used as semiconductor materials for visible light emitting devices and high-temperature operating electronic devices, and are being developed in the field of blue and green light emitting diodes. .

A gallium nitride-based compound semiconductor light emitting device capable of emitting visible light basically comprises an n-type cladding layer and an InGaN serving as a light emitting layer on a substrate made of sapphire, SiC, or the like via a buffer layer. The mainstream is a laminate of a light-emitting layer made of and a p-type cladding layer. In particular, recently, a double heterostructure grown using a sapphire substrate as a substrate and a low-temperature growth buffer layer made of GaN or AlN by a metal organic chemical vapor deposition method has high luminance and high reliability. It has been widely used for light emitting diodes for outdoor panel displays and the like.

However, recently, a substrate made of GaN has been manufactured, and some gallium nitride-based compound semiconductor light emitting devices using the same have been proposed. For example, Japanese Patent Application Laid-Open No. 7-94784 discloses a blue light-emitting device in which a stacked body including a pn junction is formed on a GaN substrate. According to this publication, a structure in which GaN is used as the substrate and the substrate exists between the electrodes facing each other similarly to other red light-emitting diodes or the like is possible, and the restriction on the electrode position can be eliminated.

Further, Japanese Patent Application Laid-Open No. 10-150220 discloses a light-emitting element that uses a substrate made of n-type GaN and can use the substrate side as a main light-emitting surface side.

FIG. 3 is a cross-sectional view showing the structure of a conventional gallium nitride-based compound semiconductor light emitting device disclosed in the above publication. On a substrate 11 made of n-type GaN, n
12 cladding layers, light emitting layer 13 and p-cladding layer 1
4 are sequentially laminated, an n-side electrode 15 is provided on a part of one surface other than the lamination surface side of the substrate 11, and a p-side electrode 16 is provided over the entire surface on the p-type cladding layer 14. . By mounting the p-side electrode 16 downward,
The surface on which the n-side electrode 15 is provided is defined as the main light emitting surface side, so that surface light emission can be obtained. According to such a configuration, the current-
It is stated that an inexpensive light emitting element with improved light output characteristics can be provided.

[0007]

However, in the conventional gallium nitride-based compound semiconductor light emitting device, the substrate 11 made of GaN is transparent to the light emitted from the light emitting layer 13 like the light emitting device having the structure shown in FIG. Therefore, the side of the n-side electrode 15 provided on the substrate 11 can be used as a main light emitting surface. Since the n-side electrode 15 is usually used as a pad for wire bonding, the n-side electrode 15 is formed of a thick film that is not transparent to light emission.

Therefore, light emitted from the light emitting layer 13 below the electrode and traveling toward the main light emitting surface of the substrate 11 is blocked by the thick n-side electrode 15. For this reason,
The light distribution characteristic above the light emitting element has a concave distribution that drops above the region where the n-side electrode 15 is formed. The light distribution characteristic having such a distribution has a problem that it is not desirable in applications that require uniform light distribution characteristics and high luminous intensity right above the light emitting element.

If the size of the n-side electrode 15 is reduced in order to increase the area of the substrate 11 serving as the main light emitting surface in order to avoid such a concave distribution, the work of wire bonding becomes difficult. It is not preferable to reduce the size of No. 15. Therefore, there is a demand for a light-emitting element that can improve the light-emitting characteristics even while ensuring the workability of electrical connection such as bonding.

The present invention solves the above-mentioned conventional problems. In a light-emitting element using a substrate made of a gallium nitride-based compound semiconductor and using the substrate side as a main light-emitting surface, the light-emitting element is disposed directly above the light-emitting element. It is an object of the present invention to provide a gallium nitride-based compound semiconductor light emitting device having a novel structure capable of improving light characteristics and maintaining high light emission intensity.

[0011]

In order to solve the above problems, a gallium nitride based compound semiconductor light emitting device according to the present invention comprises:
On a first main surface of a substrate made of a light-transmitting n-type gallium nitride-based compound semiconductor having a first main surface and a second main surface,
A laminated structure is provided in which at least an n-type clad layer made of a gallium nitride-based compound semiconductor, a light-emitting layer, a p-type clad layer, and a p-type contact layer are laminated, and an n-side electrode is partially formed from the surface side of the laminated structure. Is provided in direct contact with the exposed surface of the substrate, and the p-side electrode is
The substrate is provided in contact with the surface of the mold contact layer, and the second main surface of the substrate is a main light emitting surface.

Further, in the present invention, the substrate may be made of Ga.
N and the n-cladding layer is Al _xGa_1-xN (0 ≦ x
≦ 0.5).
The lad layer has at least Al provided on the substrate side._yGa
_1-yN (0 ≦ y ≦ 0.2) and Al provided on the light emitting layer side_z
Ga_1-zN (0 <z ≦ 0.5, y <z)
It is characterized by the following.

Further, in the present invention, the p-type cladding layer is made of Al _u Ga _1-u N (0 <u ≦ 0.5), and the p-type contact layer is made of Al _v Ga _1-v N (0 ≦ v ≦ 0.
2, v <u).

Further, in the present invention, the p-type cladding layer and the p-type contact layer have the same composition of Al _w Ga
_1-w N (0 ≦ w ≦ 0.2).

According to such a configuration, the light distribution characteristics immediately above the light emitting element can be improved, and the emission intensity can be kept high.

[0016]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The first aspect of the present invention is directed to a first principal surface of a substrate made of a light-transmitting n-type gallium nitride-based compound semiconductor having a first principal surface and a second principal surface. A laminated structure in which an n-type clad layer made of at least a gallium nitride-based compound semiconductor, a light-emitting layer, a p-type clad layer, and a p-type contact layer are laminated, and an n-side electrode is arranged from the surface side of the laminated structure A part of the substrate is provided in direct contact with the exposed surface of the substrate, a p-side electrode is provided in contact with the surface of the p-type contact layer, and the second main surface of the substrate emits main light. Surface,
This has the effect that the light distribution characteristics immediately above the light emitting element can be made substantially uniform.

According to a second aspect of the present invention, in the first aspect, the substrate is made of GaN, and the crystallinity of a laminated structure formed on the substrate is maintained high. And has the effect of reducing the ohmic contact resistance with the n-side electrode.

According to a third aspect of the present invention, in the second aspect, the n-type cladding layer is made of Al _x Ga ₁ -xN.
(0 ≦ x ≦ 0.5), while maintaining good crystallinity and allowing electrons injected from the n-side electrode into the substrate to spread at the interface between the substrate and the n-type cladding layer. It has the effect of being able to make it easier.

According to a fourth aspect of the present invention, in the second or third aspect of the present invention, the n-type cladding layer is formed of Al _y Ga _1-y N (0 ≦ y ≦ 0.
Consisting 2) a first Al _z provided the the light emitting layer side and the n-type cladding layer _{Ga 1-z N (0 <} z ≦ 0.5, y <z) from the consisting of the second n-type clad layer In addition to maintaining good crystallinity, electrons injected from the n-side electrode into the substrate are formed by the interface between the substrate and the first n-type cladding layer and the first n-type cladding layer. This has the effect that it can be easily spread at the interface between the mold clad layer and the second n-type clad layer.

The invention described in claim 5 is the invention according to claims 1 to 4
In the invention described in any one of the above, the p-type cladding layer is made of Al _u Ga _1-u N (0 <u ≦ 0.5), and the p-type contact layer is made of Al _v Ga _1-v N ( 0 ≦ v ≦ 0.
2, v <u), whereby electrons can be efficiently confined in the light emitting layer and ohmic contact resistance with the p-side electrode can be reduced. Having.

[0021] The invention according to claim 6 is the invention according to claims 1 to 4.
In the invention according to any one of the above, the p-type cladding layer and the p-type contact layer have the same composition of Al _w Ga _1-w
N (0 ≦ w ≦ 0.2), whereby electrons can be efficiently confined in the light emitting layer and ohmic contact resistance with the p-side electrode is reduced. It has the effect of being able to.

Hereinafter, a specific example of the embodiment of the present invention will be described.
This will be described with reference to FIG.

(Embodiment) FIG. 1 is a sectional view showing the structure of a gallium nitride based compound semiconductor light emitting device according to one embodiment of the present invention.

In FIG. 1, an n-type cladding layer 2 made of AlGaN and an I-type cladding layer 2 are formed on a substrate 1 made of n-type GaN.
A light emitting layer 4 made of nGaN, a p-type clad layer 6 made of AlGaN, and a p-type contact layer 7 made of AlGaN are sequentially stacked. A p-side electrode 8 is formed on the surface of the p-type contact layer 7, and from the surface side of the p-type contact layer 7, the p-type contact layer 7, the p-type cladding layer 6, the light emitting layer 4, and the n-type cladding layer 2 and a part of the substrate 1 are removed by etching, and n
Side electrodes 9 are formed.

[0025] The substrate 1, n-type gallium nitride compound semiconductor _{(In a Al b Ga 1 -} a - b N ( where, 0 ≦ a ≦
1,0 ≦ b ≦ 1,0 ≦ a + b ≦ 1)) can be used, good crystallinity obtained easily Al _c Ga ₁ - _c
N (however, 0 ≦ c ≦ 1) is desirable. Among them, it is most preferable to use GaN that is relatively easy to produce and provides the best crystallinity. The substrate 1 is doped with an n-type impurity such as Si or Ge, and has an electron concentration controlled in a range of approximately 1 × 10 ¹⁷ cm ⁻³ to 1 × 10 ¹⁹ cm ⁻³ . Electron concentration is 1 × 10 ¹⁷ cm
^If it is lower than ⁻³ , the ohmic contact resistance with the n-side electrode 9 increases, so that the operating voltage of the light-emitting element increases, and the resistivity of the substrate 1 increases.
This is because the electrons injected into the substrate 1 tend to be difficult to spread on the substrate 1, and if it is higher than 1 × 10 ¹⁹ cm ⁻³ , n
This is because the crystallinity of the substrate 1 tends to be deteriorated due to doping of the type impurity at a high concentration.

As the n-type cladding layer 2, an n-type gallium nitride-based compound semiconductor having a larger band gap than the light emitting layer 4 can be used. The n-type cladding layer 2 is made of GaN
Or a single layer of AlGaN, InGaN, InAlGaN, etc.,
Alternatively, a laminate of these layers can be used, but when GaN is used for the substrate 1, Al _x Ga ₁ -xN
(0 ≦ x ≦ 0.5) is preferably used. The crystallinity of the n-type cladding layer 2 can be kept good, and
By forming a hetero barrier in the conduction band at the interface between the substrate 1 and the n-type cladding layer 2, electrons injected from the n-side electrode 9 into the substrate spread evenly in the plane of the substrate 1, whereby the light emitting layer 4 To achieve uniform injection of electrons into
This is because the light emission distribution in the light emitting layer 4 becomes uniform, and as a result, uniform surface light emission is obtained on the main light emitting surface on the back surface side of the substrate 1.

The n-type cladding layer 2 is made of Al provided on the substrate side.
_a first n-type cladding layer made of yGa _1-y N (0 ≦ y ≦ 0.2) and Al _z Ga _1-z N (0 <z ≦
0.5, y <z) and a second n-type clad layer. Thereby, the n-type cladding layer 2
And the electrons injected into the substrate from the n-side electrode 9 are transferred to the interface between the substrate 1 and the first n-type cladding layer and between the first n-type cladding layer and the second n-type cladding. Spread uniformly at the interface with the layer, and uniform surface light emission can be obtained as described above. In addition, between the second n-type cladding layer and the light emitting layer 4, A having a smaller Al composition than the second n-type cladding layer.
A third n-type cladding layer made of lGaN (including GaN) may be provided.

The n-type cladding layer 2 is undoped or doped with an n-type impurity such as Si or Ge.
When the electron concentration is 1 × 10 ¹⁵ cm ⁻³ or more and 1 × 10 ¹⁹ cm
Desirably less than ^-3 . Electron concentration is 1 × 10 ¹⁵ c
When it is lower than m ⁻³ , the resistivity of the n-type cladding layer 2 increases, the series resistance of the light emitting element increases, and the operating voltage increases. When it exceeds 1 × 10 ¹⁹ cm ⁻³ , Due to the high concentration of n-type impurities, n
This is because the crystallinity of the mold cladding layer 2 tends to deteriorate.

The thickness of the n-type cladding layer 2 is 0.002 μm.
It is desirable that the thickness be in the range of not less than m and not more than 5 μm. 0.
When the thickness is smaller than 002 μm, the effect of uniformly spreading the current (electrons) tends to be reduced. When the thickness is larger than 5 μm,
This is because the series resistance of the light emitting element increases and the operating voltage increases, and it takes time to form and etch the n-type cladding layer 2. Then, the n-type cladding layer 2
By adjusting the electron concentration in accordance with the layer thickness, the series resistance can be reduced while the current spreading effect is exhibited. According to the findings of the present inventors, it is preferable to increase the electron concentration while increasing the layer thickness.

The light emitting layer 4 includes the n-type cladding layer 2 and the p-type cladding layer 2.
A gallium nitride-based compound semiconductor having a band gap smaller than the band gap of the mold cladding layer 6 can be used. In particular, InGaN and GaN that do not contain Al
Is used, the emission intensity in the ultraviolet to green wavelength range can be increased. In the case where the light emitting layer 4 contains In, when the film thickness is made smaller than 0.01 μm to form a single quantum well layer, the crystallinity of the light emitting layer 4 can be increased, and the luminous efficiency can be further increased. .

The light emitting layer 4 is a multiple quantum well in which a quantum well layer made of InGaN or GaN and a barrier layer made of InGaN, GaN, AlGaN or the like having a larger band gap than the quantum well layer are alternately stacked. It can also be structured.

As the p-type cladding layer 6, a p-type gallium nitride compound semiconductor having a larger band gap than that of the light emitting layer 4 can be used. Ga in the p-type cladding layer 6
A single layer of N, AlGaN, InGaN, InAlGaN, or the like, or a stack of these layers can be used. In particular, when Al _u Ga _1-u N (0 <u ≦ 0.5) is used, good results are obtained. This is preferable because the crystallinity can be maintained, the electrons can be efficiently confined in the light emitting layer 4, and the luminous efficiency can be increased.

The p-type cladding layer 6 is doped with a p-type impurity and has p-type conductivity. P-type impurities include M
Although g, Zn, Cd, C, and the like can be used, it is preferable to use Mg, which can be made p-type relatively easily. The p-type impurity concentration is 5 × 1 at 1 × 10 ¹⁹ cm ⁻³ or more.
Desirably, it is less than 0 ²⁰ cm ^-3 . If the p-type impurity concentration is lower than 1 × 10 ¹⁹ cm ⁻³ , the resistivity of the p-type cladding layer 6 increases, the series resistance of the light emitting element increases, and the operating voltage increases. ^If it is higher than ²⁰ cm ^-3, the crystallinity of the p-type cladding layer 6 tends to be deteriorated due to the high concentration of the p-type impurity, and the diffusion of the p-type impurity into the light emitting layer 4 becomes difficult. This is because the light emission efficiency becomes remarkable and the luminous efficiency decreases.

When the p-type cladding layer 6 is doped with a relatively high concentration of p-type impurity, the light-emitting layer 4 and the p-type cladding layer 6 are doped to suppress excessive diffusion of the p-type impurity into the light-emitting layer 4. Between them, an intermediate layer can be introduced. For this intermediate layer, InAlGaN can be used.
It is preferable to use GaN because the crystallinity at the interface with the light emitting layer 4 can be kept good. The intermediate layer is preferably undoped in order to serve as an absorption layer for p-type impurities diffused in the direction of the light emitting layer 4, and the intermediate layer has a thickness of:
It is desirable that the thickness be in the range of 0.001 μm or more and 0.05 μm or less. If the thickness is smaller than 0.001 μm, the effect of suppressing the diffusion of the p-type impurity into the light emitting layer 4 becomes small, and
This is because if the thickness is more than 05 μm, the efficiency of injecting holes into the light emitting layer 4 decreases, and the light emission efficiency decreases.

The thickness of the p-type cladding layer 6 is 0.01 μm
It is preferable to set the range to 0.5 μm or less.
When the thickness is less than 0.01 μm, electrons cannot be efficiently confined in the light emitting layer 4, and the luminous efficiency tends to decrease. This is because the voltage increases.

The p-type contact layer 7 is made of GaN or AlGa
N, InGaN, or the like can be used. In particular, Al _v Ga _{1 -v} N having a smaller Al composition than the p-type cladding layer 6.
When (0 ≦ v ≦ 0.2) is used, good crystallinity can be maintained, the contact resistance with the p-side electrode 8 can be reduced, and the operating voltage can be effectively reduced.

The p-type contact layer 7 is doped with a p-type impurity and has p-type conductivity. P-type impurities include M
Although g, Zn, Cd, C, and the like can be used, it is preferable to use Mg, which can be made p-type relatively easily. The p-type impurity concentration is 5 × 1 at 1 × 10 ¹⁹ cm ⁻³ or more.
Desirably, it is less than 0 ²⁰ cm ^-3 . When p-type impurity concentration is lower than 1 × 10 ¹⁹ cm ^-3, is because the operating voltage of the light-emitting element becomes higher becomes high ohmic contact resistance between the p-side electrode 8, from 5 × 10 ²⁰ cm ^-3 Becomes higher, the p-type impurity is doped at a high concentration.
This is because the crystallinity of the mold contact layer 7 deteriorates and it becomes difficult to obtain p-type conduction.

The thickness of the p-type contact layer 7 is 0.005
It is preferable that the thickness be in the range of not less than μm and not more than 0.5 μm. When the thickness is smaller than 0.005 μm, the ohmic contact resistance with the p-side electrode 8 increases and the operating voltage of the light emitting element increases. When the thickness is larger than 0.5 μm, the series resistance of the light emitting element increases and the operating voltage increases. Is higher.

The p-type contact layer 7 is a p-type cladding layer 6
With the same composition as described above, the p-type cladding layer 6 and the p-type contact layer 7 can be integrated as a single layer made of Al _w Ga _{1 -wN} (0 ≦ w ≦ 0.2). This gives p
The formation of the p-type cladding layer 6 and the p-type contact layer 7 can be simplified while maintaining the functions as the p-type cladding layer and the p-type contact layer.

Au, Ni, Pt, P
A single metal such as d or Mg, or an alloy or a laminated structure thereof can be used. In particular, Ag, Pt, Mg, Al, Zn, Rh, Ru, which have high reflectance with respect to the emission wavelength.
When a metal such as Pd is used, light traveling from the light-emitting layer 4 toward the p-side electrode 8 can be reflected and extracted from the back surface side of the substrate 1, which is preferable in terms of improving light emission intensity.

The n-side electrode 9 is formed on the n-side electrode 9 formed on the substrate 1.
It is formed in direct contact with the surface of the substrate 1 exposed by removing a part of the laminated structure including the mold cladding layer 2, the light emitting layer 4, the p-type cladding layer 6, and the p-type contact layer 7. . With the configuration in which the n-side electrode 9 is arranged in this manner, the back side of the substrate 1 where the laminated structure is not formed can be used as a main light emitting surface, and uniform surface light emission can be obtained on the main light emitting surface. .

The n-side electrode 9 may be a single metal such as Al or Ti, an alloy containing Al, Ti, Au, Ni, V, Cr, or the like, or a laminated structure thereof.

[0043]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a specific example of a method for manufacturing a gallium nitride based compound semiconductor light emitting device of the present invention will be described with reference to the drawings. The following examples mainly show a method for growing a gallium nitride-based compound semiconductor using a metal organic chemical vapor deposition method, but the growth method is not limited to this, and the molecular beam epitaxy method and the organic metal It is also possible to use a molecular beam epitaxy method or the like.

Example 1 FIG. 2 is a sectional view showing the structure of a gallium nitride based compound semiconductor light emitting device according to another embodiment of the present invention.

In this example, a gallium nitride-based compound semiconductor light emitting device shown in FIG. 2 was manufactured.

First, a mirror-finished surface having a thickness of about 3
00 μm, wafer-shaped n-type GaN with a diameter of about 50 mm
After placing the substrate 1 having an electron concentration of 5 × 10 ¹⁷ cm ^{−3 on} a substrate holder in a reaction tube, the temperature of the substrate 1 was set at 110 ° C.
By maintaining the substrate 1 at 0 ° C. for 10 minutes and heating the substrate 1 while flowing hydrogen gas at 4 liters / minute, nitrogen gas at 4 liters / minute, and ammonia at 2 liters / minute, organic substances adhering to the surface of the substrate 1 are heated. Cleaning was performed to remove dirt and moisture.

Next, while maintaining the temperature of the substrate 1 at 1100 ° C., while supplying nitrogen gas as a carrier gas at 15 L / min and hydrogen gas at 4 L / min, ammonia was supplied at 2 L / min and trimethylgallium was supplied. (Less than,
Abbreviated as TMG. ) At 80 μmol / min, 10 ppm
The diluted monosilane was supplied at a rate of 2 cc / min, and the first n-type cladding layer 2 made of Si-doped GaN was supplied at 1 μm.
m. The electron concentration of the first n-type cladding layer 2 was 2 × 10 ¹⁷ cm ⁻³ .

After growing the first n-type cladding layer 2, the substrate 1
While maintaining the temperature of 1100 ° C., ammonia was supplied at a rate of 2 liters / minute while flowing nitrogen gas at 15 liters / minute and hydrogen gas at 4 liters / minute as a carrier gas.
TMG at 40 μmol / min and trimethylaluminum (hereinafter abbreviated as TMA) at 3 μmol / min, 10 μmol / min.
Supplied at 1 cc / min.
A second n-type cladding layer 3 made of i-doped Al _0.05 Ga _0.95 N was grown to a thickness of 0.05 μm. The electron concentration of the second n-type cladding layer 3 is 2 × 10 ¹⁷ cm ⁻³
Met.

After growing the second n-type cladding layer 3, TMG
And the supply of TMA are stopped, the temperature of the substrate 1 is lowered to 700 ° C., and the temperature is maintained at this temperature.
Liter / min, TMG 4 μmol / min, trimethylindium (hereinafter abbreviated as TMI) 1 μmol / min.
The light emitting layer 4 having a single quantum well structure made of undoped In _0.15 Ga _0.85 N was grown to a thickness of 0.002 μm.

After the light emitting layer 4 is grown, the supply of TMI is stopped.
While flowing nitrogen gas as a carrier gas at a rate of 15 liters / minute, ammonia was used at a rate of 6 liters / minute, and TMG was 2 μm.
The intermediate layer 5 made of undoped GaN was grown to a thickness of 0.004 μm while increasing the temperature of the substrate 1 to 1050 ° C. while supplying the solution at ol / min.

When the temperature of the substrate 1 reaches 1050 ° C.,
15 l / min of nitrogen gas as carrier gas and hydrogen
While flowing the gas at 4 liters / min, remove 2 ammonia
Tol / min, TMG 40μmol / min, TMA 7μ
mol / min, biscyclopentadienyl magnesium
(Hereinafter Cp_TwoAbbreviated as Mg. ) At 0.1 μmol /
Min, supplied with Mg-doped Al_0.1Ga_0.9N
The p-type cladding layer 6 is grown to a thickness of 0.1 μm.
Was. The Mg concentration of the p-type cladding layer 6 is 1 × 10 ²⁰cm
^-3Met.

After the growth of the p-type cladding layer 6, while keeping the temperature of the substrate 1 at 1050 ° C., 15 liters / minute of nitrogen gas and 4 liters / hour of hydrogen gas are used as carrier gases.
While flowing ammonia in 2 liters / minute, TMG
40 μmol / min, TMA 3 μmol / min, Cp ₂
Mg was supplied at a rate of 0.1 μmol / min, and a p-type contact layer 7 made of Mg-doped Al _0.05 Ga _0.95 N was grown to a thickness of 0.1 μm. The Mg concentration of this p-type contact layer 7 was 1 × 10 ²⁰ cm ⁻³ .

After growing the p-type contact layer 7, TMG and T
The supply of MA and Cp ₂ Mg was stopped, and the temperature of the substrate 1 was cooled to about room temperature while flowing nitrogen gas at 8 L / min and ammonia at 2 L / min. The wafer on which the semiconductor was stacked was taken out of the reaction tube.

The thus-formed laminated structure made of a gallium nitride-based compound semiconductor is not separately annealed, but a SiO ₂ film is deposited on the surface thereof by a CVD method, followed by photolithography and wet etching. To form an SiO ₂ mask for etching. Then, by a reactive ion etching method, the p-type contact layer 7, the p-type cladding layer 6, the intermediate layer 5, the light emitting layer 4, and the second n-type cladding layer 3 are formed.
And the first n-type cladding layer 2 and a part of the substrate 1
at a depth of m in the direction opposite to the stacking direction,
The surface of the substrate 1 was exposed. Then, an n-side electrode 9 in which 0.1 μm thick Ti and 0.5 μm thick Au were laminated was formed on a part of the exposed surface of the substrate 1 by photolithography and vapor deposition. Further, after the etching SiO ₂ mask is removed by wet etching, a 0.3 μm thick Pt layer is formed on almost the entire surface of the p-type contact layer 7 by photolithography and vapor deposition.
A p-side electrode 8 made of Au and 0.5 μm thick was formed by vapor deposition.

Thereafter, the back surface of the substrate 1 is polished to 100 μm.
The thickness was adjusted to about m and separated into chips by scribing. Thus, the gallium nitride based compound semiconductor light emitting device shown in FIG. 2 was obtained.

The light emitting element was placed on a Si diode having a pair of positive and negative electrodes with the electrode forming surface side facing downward.
Adhered by u bump. At this time, the light emitting element is mounted such that the p-side electrode 8 and the n-side electrode 9 of the light emitting element are connected to the negative electrode and the positive electrode of the Si diode, respectively. Thereafter, the Si diode on which the light emitting element was mounted was mounted on the stem using Ag paste, the positive electrode of the Si diode was connected to the electrode on the stem with a wire, and then resin molded to produce a light emitting diode. When this light-emitting diode was driven with a forward current of 20 mA, it emitted blue light with a peak emission wavelength of 470 nm.
, Uniform surface light emission was obtained from the back side. At this time, the light emission output was 3 mW, and the forward operation voltage was 3.4 V.

Example 2 Example 2 is different from Example 1 in that the p-type cladding layer 6 and the p-type contact layer 7 were integrated as a single layer made of Mg-doped Al _0.05 Ga _0.95 N. Prepared a light emitting diode in the same procedure as in Example 1 above.

Specifically, after growing up to the intermediate layer 5 in the same procedure as in the first embodiment, when the temperature of the substrate 1 reaches 1050.degree.
Ammonia and 2 L / min, TMG 40 μmol / min, T
MA is 3 μmol / min, and biscyclopentadienyl magnesium (hereinafter abbreviated as Cp ₂ Mg) is 0.1 μm.
mol / min, Mg-doped Al _0.05 G
A single layer of a _0.95 N p-type cladding layer 6 and p-type contact layer 6 was grown to a thickness of 0.2 μm. The Mg concentration of this single layer was 1 × 10 ²⁰ cm ⁻³ .

A light emitting diode was manufactured in the same manner as in Example 1 except that the p-type cladding layer 6 and the p-type contact layer 7 were integrated as a single layer. When this light-emitting diode was driven with a forward current of 20 mA, it emitted blue light with a peak emission wavelength of 470 nm.
, Uniform surface light emission was obtained from the back side. At this time, the light emission output was 3 mW, and the forward operating voltage was 3.4 V.

[0060]

As described above, according to the gallium nitride-based compound semiconductor light emitting device of the present invention, a substrate made of a gallium nitride-based compound semiconductor is used, and the back side of the substrate on which the laminated structure including the light emitting layer is not formed is formed. In the light emitting element with the main light emitting surface side, the light distribution characteristics right above the light emitting element can be improved and the light emission intensity can be kept high. Therefore, a uniform light distribution right above the light emitting element is desired. It can be suitably used for applications such as a linear light source in which a plurality of light emitting diodes and light emitting elements are arranged on a substrate.

Further, since the light emission intensity directly above the light emitting element can be kept high, it can also be used for a conventional light emitting diode with a resin lens having a shell shape.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view illustrating a structure of a gallium nitride-based compound semiconductor light emitting device according to an embodiment of the present invention.

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

FIG. 3 is a sectional view showing the structure of a conventional gallium nitride-based compound semiconductor light emitting device.

[Explanation of symbols]

 Reference Signs List 1 substrate 2 n-type clad layer or first n-type clad layer 3 second n-type clad layer 4 light emitting layer 5 intermediate layer 6 p-type clad layer 7 p-type contact layer 8 p-side electrode 9 n-side electrode

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Shuichi Shinagawa 1006 Kazuma Kadoma, Osaka Pref. Matsushita Electric Industrial Co., Ltd. F-term (reference) 5F041 AA04 AA14 CA04 CA05 CA13 CA34 CA40 CA53 CA57 CA65 CA66 CA74 CA82 CA92 DA02 DA07 DB01 DB07 DB09

Claims (6)

[Claims] 1. A light-transmitting n-type gallium nitride-based compound semiconductor substrate having a first main surface and a second main surface, comprising at least a gallium nitride-based compound semiconductor on a first main surface. A laminated structure in which an n-type clad layer, a light-emitting layer, a p-type clad layer, and a p-type contact layer are laminated is provided, and the n-side electrode is partially removed from the surface side of the laminated structure and is exposed. A p-side electrode is provided in direct contact with the surface of the substrate, and a p-side electrode is provided in contact with the surface of the p-type contact layer;
A gallium nitride-based compound semiconductor light emitting device, wherein the second main surface of the substrate is a main light emitting surface. 2. The gallium nitride based compound semiconductor light emitting device according to claim 1, wherein said substrate is made of GaN. 3. The method according to claim 1, wherein the n-type cladding layer is formed of Al _x Ga ₁ -xN (0
≦ x ≦ 0.5), wherein the gallium nitride-based compound semiconductor light emitting device according to claim 2, wherein 4. An n-type cladding layer comprising: a first n-type cladding layer made of Al _y Ga _1-y N (0 ≦ y ≦ 0.2) provided on at least the substrate side; Al _z provided
4. A gallium nitride-based compound semiconductor according to claim 2, wherein the gallium nitride-based compound semiconductor comprises a multi-layered structure with a second n-type clad layer made of Ga _{1 -zN} (0 <z ≦ 0.5, y <z). Light emitting element. 5. The semiconductor device according to claim 1, wherein said p-type cladding layer is made of Al _u Ga _{1 -uN} (0
<U ≦ 0.5), and the p-type contact layer is made of Al
_The gallium nitride-based compound semiconductor light-emitting device according to any one of claims 1 to 4, comprising vGa1 _-vN (0≤v≤0.2, v <u). 6. The semiconductor device according to claim 1, wherein said p-type cladding layer and said p-type contact layer are made of Al _w Ga _{1 -wN} (0 ≦ w ≦ 0.2) having the same composition. The gallium nitride-based compound semiconductor light-emitting device according to claim 1.