JPH06163989A - Semiconductor light-emitting element and light-emitting device - Google Patents

Abstract

PURPOSE:To realize multi-wavelength light emission, by a method wherein a film composed of material in which epitaxial growth is not generated is formed on a single-crystal semiconductor light-emitting element, and a light- emitting element which has a P-N junction and a PIN junction in the inside is formed on the film. CONSTITUTION:An N-GaP layer 2 doped with N, and a P-GaP layer 3 are formed in order on a single crystal N-GaP substrate 1 by an LPE method. By a CVD method, an SiO2 film 4 of 0.5mum in thickness is formed, on which about 30mum diameter grains composed of AlGaAs are grown. A P-type polycrystalline AlGaAs layer 5 and an N-type polycrystalline AlGaAs layer 6 are successively grown. An N-type electrode 10 and a P-type electrode 9 are formed on the surface of polycrystalline AlGaAs layer 6 are formed. A P-type electrode 8 is formed on the P-type GaP layer 3. When a forward direction bias is applied across the electrodes 7-8, green light of wavelength 550nm is emitted. When a forward direction bias is applied across the electrodes 9-10, red light is emitted from a region 12.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an injection type semiconductor light emitting device, and more particularly to a semiconductor light emitting device and a semiconductor light emitting device which can be used in a multi-color display or the like and which can output multiple wavelengths.

[0002]

2. Description of the Related Art A typical example of a light emitting element is a light emitting diode (LED) and a semiconductor laser or a laser diode (LD (Laser Diode)).
It has been known. Light emitting diodes and semiconductor lasers are compound semiconductors (GaAs, GaP, AlGaAs, etc.)
Alternatively, a pin junction is formed, a forward voltage is applied to the pin junction, carriers are injected into the junction, and a light emission phenomenon that occurs in the process of recombination thereof is used. Conventionally, such LEDs and LDs are formed on a single crystal substrate such as GaAs or InP on which GaAs, AlGaAs, InP, InGa are formed.
Compound semiconductors such as AsP that are lattice-matched to each substrate are LPE (liquid phase epitaxy) method, MOCVD (metal
organic chemical vapor deposition) method, VPE (vapo
rphase epitaxy) method, MBE (molecular beam epitaxy)
Epitaxial growth using crystal growth methods such as
It has been manufactured by subjecting it to processing. LED or L
D is formed by sequentially epitaxially growing a semiconductor material having the same conductivity type as the single crystal substrate and a semiconductor material having a conductivity type different from that on one surface of the n-type or p-type single crystal substrate to form a pn junction or a pin junction. There is. Then, light is emitted by passing a current between the single crystal substrate and the electrodes provided on the surface of the epitaxial growth film.

[0003]

On the other hand, a multi-color display using LEDs is manufactured by arranging light emitting diodes having different emission wavelengths as shown in FIG. FIG. 5 shows a case where surface emitting type light emitting diodes of two colors, red and green, are used. A red light emitting diode 51 and a green light emitting diode 52 as a pair are die-bonded on the X wiring 53 on the ceramic multilayer wiring board 50, and the other electrodes of the light emitting diode are bonded to the YR wiring 54 and the YG wiring 55, respectively. FIG. 6 shows this matrix wiring, for example, when a forward voltage is applied between X _{2 and} Y ₁ G, the green light emitting diode D ₂₁ G is turned on. See also X ₃
When an electric field is applied simultaneously to -Y ₂ R and X ₃ -Y ₂ G, D
It is observed that ₃₂ R and D ₃₂ G simultaneously emit light and emit yellow light. However, this display requires two elements to form one dot. Therefore, the manufacturing work of the display was very costly. Therefore, it is an object of the present invention to provide a semiconductor light emitting device capable of outputting multiple wavelengths with one device when manufacturing a display or the like, and to shorten the manufacturing process of a light emitting device using the light emitting device.

[0004]

The above object of the present invention can be achieved by the following constitutions. That is, a film made of a material that does not cause epitaxial growth is formed on a single crystal semiconductor light emitting device that emits light by injecting a current into a pn junction, a pin junction, or the like, and at least a pn junction is formed inside the film. A polycrystalline semiconductor light emitting device that has a pin junction or a similar type and emits light by current injection is formed, and an independent bias can be applied to the junction of the single crystal semiconductor light emitting device and the polycrystalline semiconductor light emitting device. A semiconductor light emitting element capable of controlling the respective light emission or a light emitting device using the light emitting element. Here, a pn junction of the single crystal semiconductor light emitting device,
The pin junction or a similar junction and the pn junction, the pin junction, or a similar junction of the polycrystalline semiconductor light emitting element have different light emission mechanisms, or the band gap of the semiconductor material forming the junction is different, and both wavelengths are different. It can be configured to emit light.

The present invention is characterized in that a normal single crystal light emitting device is covered with an insulating amorphous, ceramic, metal, polycrystal or single crystal material, and a polycrystal semiconductor light emitting device is formed thereon. Is. The polycrystalline semiconductor light emitting element is characteristically inferior to that of a single crystal when examined from the example of a silicon electronic device. However, in the case of an LED, the size thereof functions at several tens of μm, so that if each grain is several tens of μm or more, it is possible to obtain a device comparable to the single crystal light emitting device. Of course, even if the grain size is smaller than that, it functions as an LED.
The present invention relates to an LED manufactured on an amorphous or polycrystalline substrate that is cheaper than a conventional compound semiconductor substrate. Since a large area of a typical glass as an amorphous substrate is easily available, a light emitting element array having a length of 10 cm or more for a printer or an image sensor can be cut out from one substrate, which is conventionally required. It eliminates the need for aligned elements.

A feature of the present invention is that a polycrystalline semiconductor light emitting element formed on a single crystal semiconductor light emitting element forms a polycrystalline semiconductor functioning as a light emitting element on a substrate made of a material that does not cause epitaxial growth. Here, the substrate made of a material that does not cause epitaxial growth does not need to be a single crystal, and an amorphous or polycrystalline material can be used. Therefore, since a material such as glass or ceramic can be used, a very wide range of device materials can be used. In carrying out the present invention, the biggest problem is to produce a polycrystalline film made of large grains (single crystal in a polycrystalline film) on a substrate made of a material that does not cause epitaxial growth, such as amorphous, ceramic, or polycrystalline. It is in. If a large grain can be formed, it can function as a semiconductor light emitting element.

When forming a polycrystalline film on a polycrystalline substrate, the grain size is influenced by the grain size of the substrate. For example, the polycrystalline film is formed on a quartz glass substrate which is an amorphous substrate by the MOCVD method. In that case, the size of the grain changes depending on the growth conditions. For example, grain growth temperature, grain growth pressure, grain growth rate,
The grain size can be controlled by controlling the raw material supply rate and the carrier gas flow rate. For example, the higher the growth temperature and the lower the growth pressure, the larger the grain size obtained. In a preliminary experiment of growing GaAs at 850 ° C. under a pressure of 10 Torr, a polycrystalline film made of grains having a diameter of 30 μm or more was obtained.

As described above, by optimizing the conditions by the MOCVD method, it becomes possible to manufacture a polycrystalline film made of grains having a size larger than that obtained in the preliminary experiment. When p-type and n-type AlGaAs films are grown on this substrate, the p-type and n-type films become polycrystals having the same size as or larger than the polycrystal film which is the substrate. As long as the size corresponds to the size of the LED, the same characteristics as those of the single crystal element can be obtained.
On the contrary, when the size of the grain is smaller than the size of the element, there is a considerable grain boundary in the element. In the grain boundary, carriers undergo non-radiative recombination. However, this does not mean that all non-radiative recombination of carriers is caused, but the radiative recombination becomes dominant depending on the size of the grains. That is, although the performance is slightly inferior to that of the single crystal LED, an LED that sufficiently functions as an LED can be obtained. In the present invention, p
A junction similar to an n-junction or a pin-junction means a junction such as a Schottky junction that occurs when a semiconductor comes into contact with a metal.

In the above description, the case where quartz glass is used as the polycrystalline substrate has been described, but the invention is not limited to this.
For example, metals, multi-component glasses, crystallized glasses, ceramics, semiconductors, etc. can also be used. In addition, various oxides such as SiO ₂ and SiN formed on various substrates by the CVD method, the sputtering method, the vapor deposition method, or the like.
Any amorphous or polycrystalline material such as a nitride such as, a carbide such as SiC, or a film made of a metal may be used. However, when the light is also extracted to the substrate side, the substrate must be transparent or semitransparent to the emitted light.

AlG is used as a polycrystalline semiconductor light emitting device.
I mentioned the growth of aAs, but it is not limited to this.
aP, InP, InGaAsP, ZnS, ZnSe, C
It can be applied to various semiconductor materials such as dTe. Further, as a method for forming a polycrystalline film, other crystalline film growth methods such as MBE method and VPE method can be used in addition to the MOCVD method. The present invention is a semiconductor light emitting device in which a polycrystalline light emitting device is formed on a single crystal light emitting device and which can output multiple wavelengths, but a device can also be formed from this semiconductor light emitting device.

[0011]

[Function] An amorphous, ceramic or polycrystalline substrate, a single crystal substrate whose substrate has a different crystal structure from the semiconductor material to be produced, or a substrate having the same crystal structure but having a large difference in lattice constant, Epitaxial growth of crystals does not occur on the entire surface of the substrate. However, the microcrystals generated on the substrate at the initial stage of growth act as crystal nuclei, and the nuclei grow to form a polycrystalline film. If the size of each grain of the polycrystalline film is larger than the device size, the device fabricated on the polycrystalline film can obtain the same characteristics as the single crystal device. Thus, according to the present invention, the polycrystalline semiconductor light emitting element can be formed on the single crystal semiconductor light emitting element, and light can be emitted at different wavelengths.

[0012]

Embodiments of the present invention will be described with reference to the drawings. Example 1 FIG. 1 shows a schematic perspective view of an element manufactured in the first example of the present invention. On a single crystal n-GaP substrate 1, an N-GaP layer 2 and a p-GaP layer 3 each doped with N, which is an emission center, were sequentially grown by a liquid phase epitaxial growth (LPE) method.
At this time, Te is used as the n-type impurity and Z is used as the p-type impurity.
n was used. CVD on the single crystal semiconductor thus obtained
Method was used to form a 0.5 μm SiO ₂ film 4. Then, this substrate was introduced into a MOCVD chamber, heated to 850 ° C., and a first Zn-doped p-type polycrystalline AlGaAs layer was grown at a pressure of 10 Torr. Here, trimethylgallium, trimethylaluminum was used as a Group ₃ raw material, arsine (AsH ₃ ) was used as a Group 5 raw material, and hydrogen was used as a carrier gas. The 5/3 ratio represented by (molar flow rate of group 5 raw material per unit time) / (molar flow rate of group 3 raw material per unit time) was set to 40, and the raw material was supplied for 1 hour. As a result, AlGaAs is formed on the SiO ₂ film 4.
Grains (not shown) composed of (x = 0.4) and having a diameter of about 30 μm grew. In order to improve the electrical properties of the polycrystalline film, Zn was continuously formed at 800 ° C. under normal pressure.
A p-type polycrystalline AlGaAs (x = 0.4) layer 5 doped with was grown for 1 hour. Then, Se-doped n-type polycrystalline AlGaAs (x = 0.4) layer 6 at 800 ° C.
Were grown for 30 minutes. Polycrystalline AlG thus obtained
An n-type electrode 10 is formed on the surface of the aAs layer 6, and a p-type electrode 9 and Si are formed on the p-type polycrystalline AlGaAs layer 5 exposed by etching.
The O ₂ film is removed, the single crystal p-type GaP layer 3 is exposed, and the p-type electrode 8 is formed on the back surface of the single-crystal GaP substrate 1.
The mold electrodes 7 were formed by vapor deposition.

The pn junction of the single-crystal GaP semiconductor (layers 1 to 3) obtained in this example has the current-voltage characteristics found in a normal light emitting diode, but the polycrystalline AlGaAs semiconductor (layers 5 to 6). The pn-junction also showed good rectifying characteristics as shown in FIG. When a forward bias was applied between the electrodes 7 and 8, green light emission with a peak of about 550 nm was observed from the region 11, and when a forward bias was applied between the electrodes 9 and 10, red light was emitted from the region 12. Was observed. The spectrum of this emission is, as shown in FIG.
It has two peaks near 640 nm and around 730 nm. The former is light emission based on the band edge, and the latter is light emission based on the deep level. In the above embodiment, an example was shown in which a polycrystalline semiconductor light emitting element was formed on one side of a single crystal semiconductor light emitting element, but the present invention is not limited to this, and the composition of the light emitting layer is changed on both sides of the single crystal semiconductor light emitting element. Alternatively, it is possible to oscillate at different wavelengths by using materials having different light emission mechanisms.

Example 2 As a second example of the present invention, Ga is formed by MOCVD.
Regarding an example in which a pin junction type light emitting diode made of polycrystalline AlGaAs is manufactured on the P light emitting diode,
This will be described with reference to FIG. As the substrate, the single crystal GaP semiconductor (layers 1 to 3) having the N-doped pn junction manufactured by the LPE method shown in Example 1 was used. A 0.5 μm SiO ₂ film 14 was formed on this single crystal GaP semiconductor by the CVD method. Then, this substrate was introduced into a MOCVD chamber, heated to 850 ° C., and a first Zn-doped p-type polycrystalline AlGaAs layer was grown at a pressure of 10 Torr. Here, trimethylgallium, trimethylaluminum was used as a Group ₃ raw material, arsine (AsH ₃ ) was used as a Group 5 raw material, and hydrogen was used as a carrier gas. (Mole flow rate of Group 5 raw material per unit time) / (3
The 5/3 ratio represented by the group raw material (molar flow rate per unit time) was set to 40, and the raw material was supplied for 1 hour. As a result, SiO
A grain (not shown) of AlGaAs (x = 0.4) having a diameter of about 30 μm was grown on the ₂ film 14. In order to improve the electrical characteristics of the polycrystalline film, p-type polycrystalline Al doped with Zn at 800 ° C. is then used under normal pressure.
The GaAs (x = 0.4) layer 15 was grown for 1 hour. Then, a non-doped AlGaAs (x = 0.4) layer 16 was grown to a thickness of about 0.1 μm. Then, S at normal pressure 800 ℃
n-type polycrystalline AlGaAs doped with e (x = 0.4)
Layer 17 was grown for 30 minutes. The n-type electrode 21 is formed on the surface of the polycrystalline AlGaAs layer 17 thus obtained, and the p-type electrode 20 and the SiO ₂ film are removed on the p-type polycrystalline AlGaAs layer 15 exposed by etching to expose the single crystal p-type GaP3. Then, a p-type electrode 19 was formed thereon, and an n-type electrode 18 was formed on the back surface of the single crystal GaP substrate 1 by vapor deposition.

The pin junction of the single-crystal GaP semiconductor (layers 1 to 3) produced in this example provided the current-voltage characteristics found in ordinary light emitting diodes. In addition, polycrystalline AlGa
With the As semiconductor (layers 15 to 17), the current-voltage characteristic having the same rectifying property as in FIG. 2 was obtained. When a forward bias was applied between the electrodes 18 and 19, the area 22 was exposed to about 550n.
Green emission and light with a peak of m is observed, and electrode 2
When a forward bias was applied between 0 and 21, the region 23
From this, red emission was observed. As shown in FIG. 3, the spectrum of this emission has two peaks near 640 nm and around 730 nm. The former is emission based on the band edge, and the latter is emission based on a deep level. In the above embodiment, an example was shown in which a polycrystalline semiconductor light emitting element was formed on one side of a single crystal semiconductor light emitting element, but the present invention is not limited to this, and the composition of the light emitting layer is changed on both sides of the single crystal semiconductor light emitting element. Alternatively, it is possible to emit light at different wavelengths by using materials having different light emission mechanisms.

[0016]

Since the light emitting device according to the present invention can emit light of two or more different wavelengths with a single semiconductor light emitting device, when it is applied to a multi-color display, for example, the number of devices is halved. It is possible to reduce the above. Further, when applied to an optical printer, by using the light of one wavelength for erasing the photosensitive drum and the other for writing, it is not necessary to separately prepare an erasing light source which has been conventionally required. Further, in the application to optical communication, it becomes possible to provide a light source for wavelength division multiplexing communication.

[Brief description of drawings]

FIG. 1 is a schematic view of an AlGaAs (pn junction) polycrystalline light emitting device formed on a GaP single crystal light emitting device according to an embodiment of the present invention.

FIG. 2 is a current-voltage characteristic diagram of the light emitting device of FIG.

FIG. 3 is a diagram showing an emission spectrum of the light emitting device of FIG.

FIG. 4 is a schematic view of an AlGaAs (pin junction) polycrystalline light emitting device formed on a GaP single crystal light emitting device according to an embodiment of the present invention.

FIG. 5 is a diagram showing a layout of a conventional LED display.

6 is a wiring diagram of the LED display of FIG.

[Explanation of symbols]

1 ... n-type single crystal GaP substrate, 2 ... n-GaP layer, 3 ... p
-GaP layer, 4, 14 ... SiO ₂ film, 5, 15 ... p-type polycrystalline AlGaAs layer, 6, 17 ... n-type polycrystalline AlGaA
s layer, 7, 10, 18, 21 ... N-type electrode, 8, 9, 1
9, 20 ... P-type electrode, 16 ... Non-doped AlGaAs
Layers, 50 ... Alumina multilayer wiring board, 51 ... Red light emitting diode, 52 ... Green light emitting diode, 53 ... X wiring, 5
4 ... YR wiring, 55 ... YG wiring

Claims (3)

[Claims] 1. A film made of a material in which epitaxial growth does not occur is formed on a single crystal semiconductor light emitting device that emits light by injecting a current into a pn junction, a pin junction, or the like, and at least an inside of the film is formed on the film. It is possible to form a polycrystalline semiconductor light emitting element which has a pn junction, a pin junction or a similar junction and emits light by current injection, and to apply an independent bias to the junction of the single crystal semiconductor light emitting element and the polycrystalline semiconductor light emitting element. Have a structure,
A semiconductor light emitting device characterized in that each light emission can be controlled. 2. A pn junction of the single crystal semiconductor light emitting device,
The pin junction or a similar junction and the pn junction, the pin junction, or a similar junction of the polycrystalline semiconductor light emitting element have different light emission mechanisms, or the band gap of the semiconductor material forming the junction is different, and both wavelengths are different. 2. The semiconductor light emitting device according to claim 1, wherein the semiconductor light emitting device has a structure for emitting light. 3. A light emitting device using the semiconductor light emitting element according to claim 1.