JPH0653549A - Semiconductor light emitting element and fabrication thereof - Google Patents

Abstract

PURPOSE:To obtain a highly accurate, high luminance flat panel display which can emits light in multicolor. CONSTITUTION:In a semiconductor LED comprising a plurality of semiconductor layers 3, 4 of InxGa1-xN (0<=x<=1) having a light emitting part of an junction on a substrate 1, a buffer layer 2 having an AlN layer or a GaN layer is interposed between respective semiconductor layers in order to retard lattice distortion in upper or lower semiconductor layer. Furthermore, light emitting part of each semiconductor layer is exposed. In other words, each light emitting part exists independently with no overlap. This constitution realizes separate control of light emission of each semiconductor layer.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor light emitting device and a method for manufacturing the same, and more particularly to a semiconductor light emitting device capable of producing multicolor light emission and capable of producing a high-luminance, high-definition flat panel display and its manufacture. Regarding the method.

[0002]

2. Description of the Related Art Recently, development of thin and lightweight image display devices has been actively conducted. In particular, a liquid crystal display (LCD) is popular because it consumes less power and can be made compact. However, it has a drawback that it is difficult to see when the surroundings are bright.

On the other hand, light emitting diodes (LEDs) are easy to see even in bright places and are widely used in display devices such as various display lamps. The green and yellow-green LEDs are devices using N-doped GaP in the light emitting portion, the yellow LEDs are devices using N-doped GaAsP in the light emitting portion, and the red LEDs are Zn-O in the light emitting portion. There is an element using GaAsP or AlGaAs doped with, and each is commercialized.

However, the above LED has the following drawbacks. That is, GaP and GaAsP are indirect transition type semiconductors, and the concentration of the emission center is low because impurities are added to form the emission center. Therefore, when the current is increased, the light emission output is saturated immediately and high brightness cannot be obtained. Also, Al _x Ga _1-x As (0 ≦ x ≦ 1)
Is used as a high-intensity LED such as a stop lamp, but when the Al composition ratio x is larger than 0.45, it makes an indirect transition. Therefore, the efficiency decreases as the Al composition ratio increases, that is, as the emission wavelength decreases. Furthermore, GaP, GaAsP, and AlGaAs semiconductors do not emit blue light.

As a semiconductor material that is a direct transition type in the entire wavelength region, research on InGaN-based materials is under way. I
In nGaN, red to ultraviolet emission can be obtained by changing the composition of group III as shown in FIG. In particular, research on a device using a sapphire substrate and GaN is underway. For example, Appl.Phys.Lett.48 (1986) p.3
As shown in 53, between the sapphire substrate and GaN, A
By introducing a buffer layer made of 1N, a good GaN crystal can be obtained. Also, Jpn.J.Appl.Phys.30 (1
991) L1705, sapphire substrate and GaN
A good GaN crystal can be obtained by introducing a low-temperature grown GaN buffer layer between and. further,
Jpn.J.Appl.Phys.28 (1989) L2112, M
By irradiating g-doped GaN with an electron beam, p-type G
aN is obtained, and a high-intensity blue LED is obtained.

By the way, attempts have been made to increase the pixel density in order to increase the definition of the display. For example, as shown in FIG. 8, a light emitting device including a plurality of LEDs that emit different wavelengths has been commercialized.

[0007]

However, in the above LED, there is a limit to integration because a plurality of elements are molded into one. In order to further promote integration, it is necessary to have an element that can emit different wavelengths with one element.

The present invention is intended to solve the above-mentioned problems, and flat layers of InGaN layers having different compositions are laminated by relaxing lattice strain to enable multicolor emission, high brightness and high definition. An object of the present invention is to provide a semiconductor light emitting device capable of manufacturing a display and a method for manufacturing the same.

[0009]

A semiconductor light emitting device of the present invention is an In _x Ga semiconductor having a pn junction light emitting portion on a substrate.
_A plurality of semiconductor layers of _1-x N (0 ≦ x ≦ 1) are stacked, a buffer layer is interposed between the semiconductor layers, and the upper part of the light emitting portion of each semiconductor layer is formed above. The semiconductor layer is exposed due to a part of the semiconductor layer being missing, so that the above-mentioned object can be achieved.

The buffer layer may be composed of an AlN layer and / or a GaN layer.

The buffer layer may be formed by alternately stacking layers of AlN or GaN and In _y Ga _1-y N (0 ≦ y ≦ 1) layers.

According to the method of manufacturing a semiconductor light emitting device of the present invention, an In _x Ga _1-x N having a pn junction light emitting portion on a substrate.
A plurality of semiconductor layers made of (0 ≦ x ≦ 1) are stacked,
A method for manufacturing a semiconductor light emitting device, wherein a buffer layer is interposed between the semiconductor layers, and the upper part of the light emitting portion of each semiconductor layer is exposed due to a part of the semiconductor layer formed above being cut off. A step of stacking and forming a plurality of semiconductor layers made of the In _x Ga _{1 -x} N, a step of removing a part of the semiconductor layer to expose a portion to be the light emitting portion, and a charging of the exposed portion. And a step of irradiating particles to form a pn-junction light emitting portion, whereby the above object can be achieved.

[0013]

In the present invention, In _x Ga _1-x N (0≤x≤
1) Since the buffer layer having the AlN layer or the GaN layer is provided between the light emitting portions formed of the semiconductor layers, the lattice strain due to the difference in lattice constant between the light emitting portions can be relaxed. Since InGaN is a direct transition type semiconductor, high brightness and high efficiency light emission can be obtained.

Further, a pn junction is formed in each semiconductor layer by exposing the light emitting portion of each semiconductor layer and irradiating the exposed portion of the light emitting portion with charged particles. Therefore, light emission can be separately controlled.

[0015]

Embodiments of the present invention will be described below with reference to the drawings.

(Embodiment 1) FIG. 3 is a sectional view showing a semiconductor light emitting device of Embodiment 1 of the present invention.

In this semiconductor device, on a (0001) plane of a sapphire substrate 1, a buffer layer 2 made of AlN or GaN, a Si-doped n-In _x Ga _1-x N layer 3, and a Mg-doped high resistance In _x Ga _{1 layer are formed. -x} N layer 4, buffer layer 2 made of AlN or GaN, Si-doped n-In _x Ga _1-x N layer 5, Mg-doped high resistance In _x Ga _1-x N layer 6, buffer layer made of AlN or GaN 2, Si-doped n-In _x
Ga _1-x N layer 7 and Mg-doped high resistance In _x Ga _1-x N
Layer 8 is laminated. The buffer layer 2 made of AlN or GaN, the Si-doped n-In _x Ga _1-x N layer 5, the Mg-doped high resistance In _x Ga _1-x N layer 6, the buffer layer 2 made of AlN or GaN, the Si-doped n -InN
The layer 7 and the Mg-doped high resistance InN layer 8 are the Mg-doped high resistance In _x Ga _1-x N layer 4 and the Mg-doped high resistance In.
_{The x} Ga _1-x N layer 6 is partially removed so as to be exposed. A part of the Mg-doped high resistance In _x Ga _1-x N layer 8, M
The exposed portions of the g-doped high-resistance In _x Ga _1-x N layer 4 and the Mg-doped high-resistance In _x Ga _1-x N layer 6 are p-type regions 4a and 6a.
a, 8a, p-type Al electrodes 10, 11, 12 are provided on the p-type regions 4a, 6a, 8a, and an n-type Al electrode is provided on the side surface where the semiconductor is not exposed. 9 is provided.

The semiconductor device of Example 1 will be described with reference to FIGS.

First, as shown in FIG. 1, the sapphire substrate 1 was thermally cleaned at a substrate temperature of 1150 ° C.
After that, the substrate temperature is lowered to 600 ° C., and the sapphire substrate 1
A buffer layer 2 made of AlN or GaN is grown on the (0001) plane of the substrate, the substrate temperature is then raised to 800 ° C., and the Si-doped n-In _x Ga _1-x N layer 3 and the Mg-doped high resistance In are grown. _{The x} Ga _1-x N layer 4 was grown. Next, the substrate temperature is lowered to 600 ° C., the buffer layer 2 made of AlN or GaN is grown, and then the substrate temperature is set to 800 ° C.
The Si-doped n-In _x Ga _1-x N layer 5 and Mg.
A doped high resistance In _x Ga _1-x N layer 6 was grown. Further, the substrate temperature is lowered to 600 ° C., the buffer layer 2 made of AlN or GaN is grown, and then the substrate temperature is set to 8 °
The temperature was raised to 00 ° C., and the Si-doped n-In _x Ga _1-x N layer 7 and the Mg-doped high resistance In _x Ga _1-x N layer 8 were grown.

As a method of growing each of the above semiconductor layers, MO is used.
CVD method (organic metal compound vapor phase growth method), gas source M
The BE method (molecular beam epitaxy method) is preferred. The following compounds can be used as a source of atoms and a dopant material forming each semiconductor layer.

Ga source: trimethylgallium (TM
G) or triethylgallium (TEG), etc., Al source: trimethylaluminum (TMA) or triethylaluminum (TEA), etc. In source: trimethylindium (TMI) or triethylindium (TEI), etc. N source: ammonia (NH ₃ ). , Etc. Dopant materials: silane (SiH ₄ ) (for n-type dopants) and biscyclopentadienyl magnesium (Cp ₂ Mg) (for p-type dopants) and the like.

Next, as shown in FIG. 2, by dry etching or selective etching, the buffer layer 2 made of AlN or GaN, the Si-doped n-In _x Ga _1-x N layer 5, and the Mg-doped high resistance In _x Ga _{1 are formed. -x} N layer 6, buffer layer 2 made of AlN or GaN, Si-doped n-In _x
Ga _1-x N layer 7 and Mg-doped high resistance In _x Ga _1-x N
The layer 8 is formed of a Mg-doped high resistance In _x Ga _1-x N layer 4 and M.
The g-doped high-resistance In _x Ga _1-x N layer 6 was partially removed so as to be exposed.

Further, Mg-doped high resistance In _x Ga _1-x N
Part of the layer 8, the Mg-doped high resistance In _x Ga _1-x N layer 4 and the exposed portion of the Mg-doped high resistance In _x Ga _1-x N layer 6,
The p-type regions 4a, 6a, and 8a were formed by irradiating with an electron beam so that the arrival depth of electrons was about 0.5 μm.

Subsequently, as shown in FIG. 3, the p-type region 4
500μmφ p-type Al electrodes 10, 11, 12 on a, 6a, 8a
On the side where the semiconductor layer is not exposed,
A type Al electrode 9 is deposited. After each Al electrode was formed, it was divided into chips by dicing to obtain a semiconductor light emitting device.

In order to realize a multi-wavelength light emitting device using the above direct transition type InGaN, it is necessary to continuously grow semiconductor layers having different group III compositions. However, as shown in FIG. 8, since the lattice constants are different, lattice strain occurs when continuously grown. The lattice strain induces lattice defects, and the luminescence efficiency is reduced due to pits (holes) and cracks. Therefore, in the semiconductor device of the present invention, a buffer layer made of AlN or GaN is interposed between the respective semiconductor layers. The lattice strain can be relaxed by the buffer layer.

When each semiconductor layer is continuously grown,
A device structure for separating and controlling the light emission of each layer is required. Therefore, in the method for manufacturing a semiconductor light emitting device of the present invention,
The method includes an etching step of exposing a lower semiconductor layer by removing a part of the upper semiconductor layer, and a step of irradiating the exposed portion with charged particles. Therefore, the light emitting portions of the respective semiconductor layers are formed separately and independently, so that the light emission can be separately controlled.

The details of each semiconductor layer buffer layer are as follows.

AlN buffer layer 2: thickness of 500 Å Si-doped n-In _x Ga _1-x N layer 3: In _0.3 Ga
_0.7 N, thickness 2 μm Mg-doped high resistance In _x Ga _1-x N layer 4: In _0.3 Ga _0.7
N, thickness 0.5 μm Si-doped n-In _x Ga _1-x N layer 5: In _0.7 Ga
_0.3 N, thickness 1 μm Mg-doped high resistance In _x Ga _1-x N layer 6: In _0.7 Ga _0.3
N, thickness 0.5 μm Si-doped n-In _x Ga _1-x N layer 7: InN, thickness 1 μ
m Mg-doped high resistance In _x Ga _1-x N layer 8: InN, thickness 0.5 μm No lattice defects such as pits and cracks were observed in each semiconductor layer.

In the semiconductor light emitting device of this embodiment,
High-efficiency, high-luminance emission of red, green, and blue was obtained.

(Embodiment 2) FIG. 4 (a) is a sectional view showing a state before forming an exposed portion of a semiconductor light emitting device of embodiment 2 of the present invention, and FIG. 4 (b) is the semiconductor light emitting device. 3 is a cross-sectional view showing the buffer layer of FIG.

Buffer layer 40 of the semiconductor light emitting device of Example 2
a, 40b, 40c are the AlN layer 41 of 20 angstrom and
20 Å In _y Ga _1-y N (0 ≦ y ≦ 1) layer
It is a multilayer body (150 cycles) in which 42 and 42 are alternately laminated.
In this example, the value of y is 0.3 for the buffer layer 40a,
The value is 0.7 for the buffer layer 40b and 1.0 for the buffer layer 40c.

In this semiconductor light emitting device, the AlN buffer layer 41 and the In _y Ga _{1 -y} N ( _0≤y≤
1) The structure was the same as in Example 1 except that the buffer layers 42 were alternately laminated, and the same growth method was used.

No lattice defects such as pits and cracks were found in each semiconductor layer.

Since this buffer layer has a superlattice structure, the effect of relaxing the lattice strain is higher than that of the buffer layer of Example 1, and impurities which are not removed by thermal cleaning or the like remain on the substrate. However, since the impurity is trapped in the superlattice, its adverse effect can be eliminated.

In the semiconductor light emitting device of this embodiment,
High-efficiency, high-luminance emission of red, green, and blue was obtained.

(Embodiment 3) FIG. 5 (a) is a sectional view showing a state before forming an exposed portion of a semiconductor light emitting device of embodiment 3 of the present invention, and FIG. 5 (b) is the semiconductor light emitting device. 3 is a cross-sectional view showing the buffer layer of FIG.

Buffer layer 50 of the semiconductor light emitting device of Example 3
a, 50b, 50c are buffer layers 40a, 40b, 40 of the semiconductor light emitting device of Example 2 except that the thickness of the InGaN layer is changed.
It has the same configuration as c. Specifically, it has the following configuration. In _y Ga _1-y N (0 ≦
The y ≦ 1) layer 52 has a thickness of 20 Å, the In _y Ga _1-y N (0 ≦ y ≦ 1) layer 53 on the AlN layer 51 has a thickness of 30 Å, and the AlN layer 51 has a thickness of 30 nm. _{in y Ga 1-y N (} 0 ≦ y ≦ 1) layer 54 of the upper is 40 Å, · · · an in _y on the AlN layer 51 thereon
The Ga _1-y N (0 ≦ y ≦ 1) layer 55 has a thickness of 90 Å, and the In _y Ga _1-y N (0
The ≦ y ≦ 1) layer 56 is formed by stacking an AlN layer 51 and an In _y Ga _1-y N layer (0 ≦ y ≦ 1) such as 100 Å.

In this semiconductor light emitting device, as a buffer layer, an AlN layer 51 and an In _x Ga _1-x N (0≤x≤1) layer 52,
53, 54 ... 55, 56 were formed in the same manner as in Example 1 except that the layers were alternately laminated.

No lattice defects such as pits and cracks were found in each semiconductor layer.

Since this buffer layer has a superlattice structure as in the second embodiment, the buffer layer of the first embodiment is
Furthermore, the effect of relaxing lattice strain is high.

In the semiconductor light emitting device of this embodiment,
High-efficiency, high-luminance emission of red, green, and blue was obtained.

(Embodiment 4) FIG. 6A is a cross-sectional view showing a state before forming an exposed portion of a semiconductor light emitting device of embodiment 4 of the present invention, and FIG. 6B is the semiconductor light emitting device. 3 is a cross-sectional view showing the buffer layer of FIG.

Buffer layer 60 of the semiconductor light emitting device of Example 4
The layers a, 60b, and 60c are formed by stacking a layer 61 made of AlN or GaN, an AlN layer 62, and an In _y Ga _1-y N (0 ≦ y ≦ 1) layer 63. In this embodiment, the value of y is 0.3 for the buffer layer 40a, 0.7 for the buffer layer 40b,
In c, it is set to 1.0.

This semiconductor light emitting device has an AlN layer 61, an AlN layer 62 and In _y Ga _1-y N as a buffer layer.
The layers were formed in the same manner as in Example 1 except that the (0 ≦ y ≦ 1) layers 63 were alternately laminated.

No lattice defects such as pits and cracks were found in each semiconductor layer.

Since this buffer layer has a superlattice structure as in the second embodiment, the buffer layer of the first embodiment is
Furthermore, the effect of relaxing lattice strain is high.

In the semiconductor light emitting device of this embodiment,
High-efficiency, high-luminance emission of red, green, and blue was obtained.

Although the semiconductor light emitting devices of the three primary colors of red, green and blue have been described in the above embodiments, the semiconductor layer III is used.
By changing the composition of the group element, light emission from red to ultraviolet region can be obtained. For example, if x = 0.75, a yellow semiconductor light emitting element is obtained, if x = 0.9, an orange semiconductor light emitting element is obtained, and if x = 0, an ultraviolet semiconductor light emitting element is obtained.

Although a sapphire substrate was used as the substrate, other than that, a semi-insulating ZnO substrate or SiC was used.
A substrate or the like can be used.

[0050]

As is apparent from the above description, according to the present invention, direct transition type InGaN having a different composition can be laminated while relaxing the lattice strain, so that high-luminance and high-efficiency multicolor emission can be obtained. The semiconductor light emitting device can be provided. Since this semiconductor light emitting element has a plurality of light emitting portions on one substrate, it is possible to realize a multi-color light emission, a high-luminance, high-efficiency and high-definition flat panel display.

[Brief description of drawings]

FIG. 1 is a diagram showing a manufacturing process of a semiconductor light emitting device according to a first embodiment of the present invention.

FIG. 2 is a diagram showing a manufacturing process of the semiconductor light emitting device according to the first embodiment of the present invention.

FIG. 3 is a sectional view showing a semiconductor light emitting device of Example 1 of the present invention.

FIG. 4A is a cross-sectional view showing a state before forming an exposed portion of a semiconductor light emitting element of Example 2 of the present invention,
(B) is a sectional view showing a buffer layer of a semiconductor light emitting device of Example 2 of the present invention.

5A is a cross-sectional view showing a state before forming an exposed portion of a semiconductor light emitting device of Example 3 of the present invention, FIG.
(B) is a sectional view showing a buffer layer of a semiconductor light emitting device of Example 3 of the present invention.

FIG. 6A is a cross-sectional view showing a state before forming an exposed portion of a semiconductor light emitting device of Example 4 of the present invention,
(B) is a sectional view showing a buffer layer of a semiconductor light emitting device of Example 4 of the present invention.

FIG. 7 is a perspective view showing a conventional semiconductor light emitting device.

FIG. 8 is a diagram illustrating a relationship between a composition of a Group III element of In _X Ga _{1 -X} N and a lattice constant and an energy gap.

[Explanation of symbols]

1 Sapphire substrate 2 Buffer layer made of AlN or GaN 3 Si-doped n-In _0.3 Ga _0.7 N layer 4 Mg-doped high resistance In _0.3 Ga _0.7 N layer 5 Si-doped n-In _0.7 Ga _0.3 N layer 6 Mg-doped high resistance In _0.7 Ga _0.3 N layer 7 Si-doped n-InN layer 8 Mg-doped high-resistance InN layer 4a, 6a, 8a p-type regions 10, 11, 12 p-type Al electrode 9 n-type Al electrode 40a, 40b, 40c AlN layer / In _y Ga _1-y N (0 ≦ y
≦ 1) buffer layer 50a, 50b, 50c consisting of a periodic multi-layered body AlN layer / In _y Ga _1-y N (0 ≦ y
≦ 1) buffer layer 60a, 60b, 60c consisting of an irregular multi-layer body and a layer consisting of AlN or GaN and A
a buffer layer 41, 51, 61, 63 consisting of a 1N layer / a periodic multilayer of In _y Ga _1-y N (0 ≦ y ≦ 1) layer AlN buffer layer 42, 52, 53, 54, 55, 56, 62 In _y Ga _1-y N (0 ≦ y
≤1) buffer layer

 ─────────────────────────────────────────────────── ─── Continued Front Page (72) Inventor Hiroyuki Hosoba 22-22 Nagaike-cho, Abeno-ku, Osaka-shi, Osaka Within Sharp Corporation (72) Ken Obayashi 22-22 Nagaike-cho, Abeno-ku, Osaka, Osaka Incorporated (72) Inventor Toshio Hata 22-22 Nagaike-cho, Abeno-ku, Osaka-shi, Osaka Inside Sharp Corporation (72) In-house Naohiro Suyama 22-22 Nagaike-cho, Abeno-ku, Osaka, Osaka Inside Sharp Corporation

Claims (4)

[Claims] 1. A plurality of semiconductor layers made of In _x Ga _1-x N (0 ≦ x ≦ 1) having a pn-junction light emitting portion are stacked on a substrate, and a buffer layer is interposed between the semiconductor layers. A semiconductor light emitting device which is mounted, and in which the upper part of the light emitting portion of each semiconductor layer is exposed by the lack of a part of the semiconductor layer formed above. 2. The semiconductor light emitting device according to claim 1, wherein the buffer layer comprises an AlN layer and / or a GaN layer. 3. The buffer layer is AlN or GaN
2. The semiconductor light emitting device according to claim 1, wherein the layer made of and an In _y Ga _1-y N (0 ≦ y ≦ 1) layer are alternately laminated. 4. A plurality of semiconductor layers made of In _x Ga _{1 -x} N (0 ≦ x ≦ 1) having a pn-junction light emitting portion are laminated on a substrate, and a buffer layer is interposed between the semiconductor layers. are instrumentation, further above the light emitting portion of the semiconductor layer, a method of manufacturing a semiconductor light emitting element which is exposed by the lack of part of the semiconductor layer formed on the upper, from the in _x Ga _1-x N Forming a plurality of semiconductor layers in a stacked manner, exposing a part to be the light emitting portion by removing a part of the semiconductor layer, and pn-junction light emission by irradiating the exposed part with charged particles A method of manufacturing a semiconductor light emitting device, the method including: forming a portion.