JPH0629574A - Light-emitting element and its manufacture - Google Patents

Abstract

PURPOSE:To obtain a light-emitting layer composed of gallium nitride semiconductor thin-film by providing a light-emitting layer composed of at least one single-crystal gallium nitride semiconductor on a gallium nitride semiconductor layer oriented in the direction of c-axis and also providing an electrode in a desired part. CONSTITUTION:In a sapphire R-face substrate, the R-face of a single-crystal sapphire is polished with the accuracy of + or -0.8 degree and less. A gallium nitride semiconductor layer oriented in the direction of c-axis is a gallium nitride semiconductor containing a group III element such as Ga simple substance. Many doping 12n-type carriers are generated in the gallium nitride semiconductor layer oriented in the direction of c-axis so that a resistance is made small. The c-axis oriented gallium nitride semiconductor layer reduces the miss-match of the lattice constant of the sapphire R-face substrate and gallium nitride and further forms a lattice-matching face for the single-crystal gallium nitride semiconductor thin-film to grow. Thus, it is possible to obtain a blue light- emitting element.

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 which can be used for an ultraviolet to blue light emitting diode and a laser diode which are most suitable for a light source for displays, optical communication and OA equipment.

[0002]

2. Description of the Related Art Semiconductor devices are used as display devices and various light sources in a wide variety of fields. But in the ultraviolet region ~
Blue light emitting diodes have not been put into practical use, and development is urgently needed especially for displays that require three primary colors. Although a laser diode is expected as a light source for an optical disc or a compact disc because it can increase the recording density 10 times or more, it has not been put into practical use yet. Ultraviolet to blue light emitting diodes and laser diodes include GaN, ZnSe, ZnS
It is considered to use a compound semiconductor such as SiC or SiC.

However, it is generally difficult to produce a compound semiconductor thin film having such a wide band gap, and a method for producing a thin film that can be used for a light emitting device has not yet been established. For example, gallium nitride (GaN), which is regarded as a promising blue light emitting element, has been deposited on the sapphire C surface by the MOCVD method or the VPE method [Journal of Applied Physics].
rnal of Applied Physics) 5
6 (1984) 2367-2368], it was necessary to raise the reaction temperature in order to obtain good crystals, and the production was extremely difficult. Further, since the growth is carried out at a high temperature, nitrogen becomes insufficient and becomes a defect, and the carrier density becomes extremely high, so that good semiconductor characteristics have not been obtained yet. Therefore, in order to overcome this, a buffer layer of aluminum nitride is provided on the sapphire C surface, and a GaN thin film having a relatively large film thickness is formed thereon to manufacture a semiconductor light emitting device.

Further, in an attempt to realize low temperature film formation, a method of irradiating a supplied nitrogen gas with an electron shower to activate it has been carried out [Japanese Journal of Applied Physics (Japan, J. Appl. Phy.
s. ), 20, L545 (1981)], but even with this method, a good film quality leading to light emission has not been obtained. Further, it has been attempted to form a film by using a highly active nitrogen source so as not to cause a shortage of nitrogen. Plasma is used to obtain highly active nitrogen [Journal of Vacuum Science and Technology (J. Vac. Sci.
l. ), A7, 701 (1989)] has not been successful.

The present inventors have studied to grow a gallium nitride based semiconductor thin film on the sapphire R surface.
It has not been possible to obtain a high quality gallium nitride based semiconductor thin film of a light emitting device grade. [The 51st Autumn Meeting of the Japan Society of Applied Physics, SZ1000] As described above, it is extremely difficult to obtain a light emitting layer composed of a high-quality gallium nitride based semiconductor thin film capable of producing a light emitting element, and a big problem in manufacturing a blue light emitting element. Met.

[0006]

SUMMARY OF THE INVENTION The present invention is intended to solve this problem and provide a light emitting device structure having good characteristics as a semiconductor light emitting device.

[0007]

As a result of intensive studies to solve the above problems, the present inventors have found that at least one single crystal gallium nitride based semiconductor is formed on the gallium nitride based semiconductor layer oriented in the c-axis direction. A semiconductor light emitting device having excellent characteristics can be obtained by providing a light emitting layer made of and an electrode at a desired portion.

That is, the present invention has an n-type single crystal gallium nitride having a c-axis oriented gallium nitride-based semiconductor layer formed directly on a sapphire R-plane substrate having an off angle of 0.8 degrees or less. A semiconductor layer and at least one light emitting layer made of a p-type or i-type single crystal gallium nitride semiconductor layer, and an electrode at a desired portion for applying a voltage to the light emitting layer. In the gallium nitride-based semiconductor light emitting device and the MBE method, a crystal growth apparatus having a gas source for supplying a nitrogen-containing gaseous compound and a solid source for supplying a group III element is used, and the sapphire R surface is used as a substrate surface. 0.1 to 30 by supplying a nitrogen-containing gaseous compound and a Group III element
A step of forming a gallium nitride-based semiconductor thin film oriented to the c-axis at a growth rate of angstrom / sec, an n-type single crystal gallium nitride-based semiconductor thin film is formed by supplying a nitrogen-containing gaseous compound and a group III element And a step of forming a p-type or i-type single crystal gallium nitride based semiconductor thin film by supplying a nitrogen-containing gaseous compound, a group III element and a p-type dopant. It is a method of manufacturing an element.

The present invention will be described in more detail below. Sapphire R having an off angle of 0.8 degrees or less in the present invention
A plane substrate is a polished surface in which the R plane [1, -1, 0, 2] of single crystal sapphire (α-Al ₂ O ₃ ) is a substrate surface with an accuracy of ± 0.8 degrees or less. Is. This off-angle can be measured from an X-ray rocking curve by an X-ray diffraction method using Cu-Kα rays. If the off angle is 0.8 degrees or more, a single crystal gallium nitride based semiconductor thin film having a flat surface cannot be obtained. Therefore, the off angle must be 0.8 degrees or less,
It is preferably 0.5 degrees or less, more preferably 0.3 degrees or less. Furthermore, it is necessary that the surface of the substrate allows a streak pattern to be observed by RHEED (reflection high-energy electron diffraction device).

The gallium nitride based semiconductor layer oriented in the c-axis direction in the present invention is composed of Ga alone or G
a is a gallium nitride-based semiconductor containing at least one type of Group III element mainly selected from Al or In. Further, in the present invention, it is also preferable that the gallium nitride based semiconductor layer oriented in the c-axis direction is doped to generate a large amount of n-type carriers to reduce the resistance. As an element to be doped, a normal n-type compound semiconductor used in III-V compound semiconductors is used.
Type dopants can be used, especially Si, G
Preferred are e, C, Sn, S, Se, Te and the like.

In the present invention, a c-axis oriented gallium nitride based semiconductor thin film is formed on a sapphire R-plane substrate having an off angle of 0.8 degrees or less. The film thickness is 100 to 500.
It is preferably 0 angstrom. If the thickness of the gallium nitride-based thin film formed on the sapphire R-plane substrate is 100 angstroms or less, a single crystal gallium nitride-based semiconductor thin film cannot be formed on it.
When the film thickness is 5000 angstroms or more, three-dimensional growth of gallium nitride occurs, so that there is a problem that surface flatness deteriorates. This c-axis oriented gallium nitride based semiconductor layer alleviates the mismatch of the lattice constants of the sapphire R-plane substrate and gallium nitride, and forms a lattice matching surface on which a single crystal gallium nitride based semiconductor thin film grows. Play a role. When this c-axis oriented gallium nitride based semiconductor layer is used as an electrode of a light emitting element, it is also preferable to perform n-type heavy doping on the gallium nitride based semiconductor as a method for further reducing the sheet resistance. The gallium nitride semiconductor is G on the sapphire R-plane substrate.
aN [1,1, -2,0] plane is parallel to the substrate surface c
It grows in an axial orientation. This means that when an electron beam is incident at an angle of 1 to 2 degrees with respect to the sapphire R plane substrate surface and from a direction perpendicular to the sapphire R plane projection axis of the sapphire c axis, gallium nitride is aligned in the c axis direction. A streak pattern showing the structure can be observed. On the other hand, when an electron beam is incident from a direction parallel to the sapphire R-plane projection axis of the sapphire c-axis, the structure in which the a-axis direction of gallium nitride is not oriented and fluctuates This can be confirmed by the fact that the line pattern spreads horizontally as shown.

Furthermore, according to the present invention, since a gallium nitride based semiconductor thin film having a thin film and good crystallinity can be obtained, the thin film manufacturing time for manufacturing a light emitting device can be shortened and a light emitting device can be manufactured. It has the feature that the dry etching method can be used. The total film thickness of the gallium nitride based semiconductor light emitting device is preferably 3 μm or less, more preferably 2 μm or less,
It is more preferable to set it to 1 μm or less.

The light emitting layer in the light emitting device of the present invention is n
Type, p-type, or i-type single-crystal gallium nitride-based semiconductor, for example, n / i, n / p, n / i / p,
It is also possible to use a single crystal gallium nitride based semiconductor thin film having a structure such as n ⁺ / n / p, n ⁺ / n / i, n / p / p ^+, etc. is there. It is also possible to form a quantum well structure made of a single crystal gallium nitride-based semiconductor to enhance the light emission efficiency and control the light emission wavelength. The gallium nitride-based semiconductor thin film in the present invention is composed of at least one kind of group III element selected from Al, Ga or In, and a mixed crystal can be used if necessary. It can be confirmed from the fact that the light emitting layer in the present invention has an extremely good crystal because a streak pattern is formed in the RHEED pattern regardless of whether the electron beam is incident from the a-axis direction of gallium nitride or the c-axis direction.

In the present invention, gallium nitride c-axis oriented
The light emitting layer formed on the semiconductor layer (c-axis GaN)
As an example of the structure of the light-emitting element, the c-axis Ga shown in FIG.
N / n-GaN / i-GaN, c-axis GaN / shown in FIG.
n-GaN / p-Ga_1-xIn_xN, c-axis Ga shown in FIG.
N / n-GaN / p-GaN, c-axis GaN / shown in FIG.
n-GaN / p-GaN / n-Ga_1-xIn_xN / p-G
a_1-xIn_xN, c-axis Ga shown in FIG._1-xIn_xN / n-G
a_1-xIn_xN / p-Ga_1-yIn_yN (x ≧ y), FIG.
C-axis Ga shown in_1-xIn_xN / n-Ga_1-xIn_xN / p-
Ga_1-yIn_yN / p-Ga_1-xIn_xLike N (x ≦ y)
C-axis Ga_1-xIn_xN / n-Ga_1-xIn_x
N / n-Ga_1-yIn_yN / p-Ga_1-xIn_xN (x ≦
y), c-axis Ga_1-xIn_xN / n-Ga_1-xIn_xN / i-
Ga_1-yIn_yN / p-Ga_1-xIn_xN (x ≦ y), c-axis
Ga_1-xIn_xN / n-Ga_1-xIn_xN / n-Ga_1-yI
n _yN / p-Ga_1-yIn_yN / p-Ga_1-xIn_xN (x
≦ y), c-axis Ga_1-xIn_xN / n-Ga_1-xIn_xN / p
-Ga_1-yIn_yN (x <y), c-axis Ga_1-xIn_xN / n
-Ga_1-xIn_xN / p-Ga_1-xIn_xN / p-Ga_1-y
In_yN (x> y), c-axis Ga_1-xIn_xN / n-Ga_1-x
In_xN / n-Ga_1-yIn_yN / p-Ga_1-yIn_yN
(X> y), c-axis Ga_1-xAl_xN / n-Ga_1-xAl_xN
/ N-Ga_1-yAl_yN / p-Ga_1-xAl_xN (x ≧
y), c-axis Ga_1-xAl_xN / n-Ga_1-xAl _xN / p-
Ga_1-yAl_yN / p-Ga_1-xAl_xN (x ≧ y), c-axis
Ga_1-xAl_xN / n-Ga_1-xAl_xN / n-Ga_1-yA
l_yN / p-Ga_1-yAl_yN / p-Ga _1-xAl_xN (x
≧ y), c-axis Ga_1-xAl_xN / n-Ga_1-xAl_xN / i
-Ga_{1- y}Al_yN / p-Ga_1-xAl_xN (x ≧ y), c
Axis Ga_1-xAl_xN / n-Ga_1-xAl_xN / p-Ga_1-y
Al_yN (x <y), c-axis Ga_1-xAl_xN / n-Ga_1-x
Al_xN / p-Ga_1-xAl_xN / p-Ga_1-yAl_yN
(X ≦ y), c-axis Ga_1-xAl _xN / n-Ga_1-xAl_xN
/ P-Ga_1-yAl_yN (x ≧ y), c-axis Ga_1-xAl_xN
/ N-Ga_1-xAl_xN / n-Ga_1-yAl_yN / p-Ga
_1-xAl_xN (x ≧ y), c-axis GaN / n-Ga_1-xAl_x
N / p-Ga_1-xAl_xN, c-axis GaN / n-Ga_1-xA
l_xN / p-Ga_1-yAl_yN (x ≧ y), c-axis GaN /
n-Ga_1-aIn_aN / p-Ga_1-bIn_bN / n-Al
_1-xGa_xN / n-Al_1-yGa_yN / p-Al _1-xGa_xN
(X ≧ y, a ≧ b), etc., but not limited to this
It is not something that can be done. A light emitting device having such a structure
To increase the luminous efficiency or change the emission wavelength.
It is possible to Also, various combinations of the above structures
To further increase luminous efficiency and increase the number of colors of light-emitting elements
It is also possible to do

In the light emitting device of the present invention, it is necessary to form an electrode at a desired portion in order to apply a voltage to the light emitting layer. As a material used for the electrode, a simple substance of Al or In, an alloy of Al and In, an alloy mainly containing Al or In, tin oxide, indium oxide, tin oxide-indium oxide, zinc oxide, degenerated ZnSe. Etc. Further, heat resistance can be improved by providing a metal layer of Au, Ni, Ge or the like on these electrodes. The shape of the electrode can be designed according to the application of the light emitting device and the required performance.

Next, a method of manufacturing the gallium nitride semiconductor light emitting device of the present invention will be described. MBE in the present invention
In the method, a crystal growth apparatus having a gas source for supplying a nitrogen-containing gaseous compound and a solid source for supplying a Group III element is used, and the sapphire R plane is used as a substrate plane.
A step of forming a gallium nitride-based semiconductor thin film oriented in the c-axis at a growth rate of 0.1 to 20 angstrom / sec by supplying a nitrogen-containing gaseous compound and a group III element, the nitrogen-containing gaseous compound And a group III element to form an n-type single crystal gallium nitride based semiconductor thin film, a nitrogen-containing gaseous compound, a group III element and a p-type dopant to supply a p-type or i-type A method of manufacturing a semiconductor light emitting device, comprising at least a step of forming a single crystal gallium nitride based semiconductor thin film.

Here, the gaseous compound means a compound containing the constituent elements of the thin film for supplying a desired compound semiconductor thin film crystal to grow on the substrate. As the gaseous compound, ammonia, nitrogen trifluoride, hydrazine or dimethylhydrazine may be used alone or a mixed gas containing them as a main component. Further, ammonia, nitrogen trifluoride, hydrazine or dimethylhydrazine may be diluted with an inert gas such as nitrogen, argon or helium before use. As a method of supplying these gases, a valve, a flow rate control device, and a pressure control device are connected in the middle of the pipe leading to the cell to control the mixing ratio and supply amount of these gases and to start / stop the supply. It is preferable to use a material that is capable of A gas cell can be used to supply these gases to the substrate surface, and in order to produce a good quality gallium nitride based semiconductor thin film, the gas cell is heated to a predetermined temperature to heat the compound containing nitrogen. Then, it is more preferable to supply it to the substrate surface. In order to efficiently perform heating in the gas cell, alumina, silica, boron nitride, silicon carbide or the like having excellent corrosion resistance is fibrous, flake-like, crushed, or granular and filled in the gas cell. Alternatively, it is preferable to increase the heating efficiency by making them porous and installing them in the gas cell to increase the contact area with the gaseous compound. Also,
It is also possible to activate nitrogen using a plasma gas cell and supply it to the substrate surface. The supply amount of the gaseous compound to the substrate surface needs to be larger than that of the solid source, and when the supply amount of the gaseous compound becomes smaller than the supply amount of the solid source, the element supplied from the gaseous compound from the semiconductor thin film is generated. It becomes difficult to obtain a good semiconductor thin film because the voids become large. Therefore, the supply amount of the gaseous compound is 10 times or more, preferably 100 times or more, more preferably 1000 times or more than that of the solid source.

In the present invention, the growth rate of the gallium nitride based semiconductor thin film is 0.1 to 20 angstrom / sec.
It is necessary to be. If the growth rate is less than 0.1 angstrom / sec, contamination of the film from the growth atmosphere will be large, making it impossible to produce a good quality gallium nitride-based semiconductor thin film. If it exceeds 20 angstrom / sec, island-like growth will occur. It becomes impossible to obtain a good quality gallium nitride based semiconductor thin film.

As the solid source of the present invention, as the group III element, a simple substance or alloy of a metal of the group III element, or a metal salt can be used. Group III elements are Al and G
It is at least one element selected from a and In. Further, when the gallium nitride-based semiconductor thin film of the present invention is manufactured, impurities can be doped to control carrier density and p-type, i-type or n-type conductivity type. Examples of impurities to be doped to obtain a p-type or i-type gallium nitride based semiconductor thin film are Mg and C
a, Sr, Zn, Be, Cd, Hg, Li, etc., and n
As impurities to be doped to obtain a gallium nitride based semiconductor thin film, Si, Ge, C, Sn, S, Se, T
e, etc. The type of carrier and the carrier density can be changed by changing the type and doping amount of these dopants. In this case, the doping concentration may be changed depending on the film thickness direction, or a δ-doping method may be used in which only a specific layer is doped.
Furthermore, it is possible to accelerate the control of the conductivity type by irradiating an electron beam or ultraviolet rays during the doping.

In producing a gallium nitride based semiconductor thin film by the MBE method in the present invention, a compound containing a group III element and nitrogen is simultaneously supplied to the substrate surface, or a compound containing a group III element and nitrogen is alternated. It is also possible to carry out a method of supplying it to the surface of the substrate or interrupting the growth during the growth of the thin film to promote crystallization of the thin film. Especially,
It is preferable to perform film growth while observing the RHEED pattern to confirm that streaks are visible.

Hereinafter, M using ammonia as an example
A method of manufacturing a gallium nitride based semiconductor light emitting device using a Gallium nitride based semiconductor laminated structure manufactured by the BE method will be described, but the method is not particularly limited to this.
As the apparatus, a crystal growth apparatus provided with an evaporation crucible (Knudsen cell) 2, 3, 4 and 5, a gas cell 6, and a substrate heating holder 7 in a vacuum container 1 as shown in FIG.

Ga metal was placed in the evaporation crucible 2 and heated to a temperature of 10 ¹³ to 10 ¹⁹ / cm ² · sec on the substrate surface. A gas cell 6 is used to introduce ammonia,
The substrate 8 was directly sprayed. The amount introduced was 10 ¹⁶ to 10 ²⁰ / cm ² · sec on the surface of the substrate. The evaporation crucible 3 contains In, Al, As, Sb.
Etc., and the temperature and time are controlled so that a mixed crystal compound semiconductor having a predetermined composition is formed to form a film. The evaporation crucible 4 contains Mg, Ca, Sr, Zn, Be, Cd, Hg.
, Li, etc., in the evaporation crucible 5, Si, Ge, C, Sn,
Doping is performed by adding S, Se, Te, etc., and controlling the temperature and supply time so that a predetermined supply amount is obtained.

As the substrate 8, a sapphire R surface having an off angle of 0.8 degrees or less was used and heated to 200 to 900 ° C. First, the substrate 8 is heated at 900 ° C. in the vacuum container 1, set to a predetermined growth temperature, and a growth rate of 0.1 to 20 angstrom / sec while supplying a predetermined amount of n-type dopant from the evaporation crucible 5. Then, a c-axis oriented gallium nitride based semiconductor layer having a thickness of 100 to 5000 angstrom is prepared. The c-axis-oriented gallium nitride-based semiconductor layer may be n-type doped with an evaporation crucible 5 to increase the conductivity. Further, 0.1 to 5 angstrom / on the c-axis oriented gallium nitride based semiconductor layer.
An n-type single crystal gallium nitride based semiconductor layer having a thickness of 0.05 to 2 μm was produced at a growth rate of sec. Then, the shutter of the evaporation crucible 4 is opened simultaneously with the shutter of Ga on the n-type single crystal gallium nitride based semiconductor layer, and
A gallium nitride-based semiconductor layer doped with a p-type or i-type dopant of 10000 angstrom was formed to produce a gallium nitride-based semiconductor laminated structure.

Then, the laminated thin film is subjected to a lithographic process to set the shape of the element and to provide an electrode for injecting a current. The lithography process can be performed by a process using an ordinary photoresist material, and the etching method can be a dry etching method. As the dry etching method, a usual method can be used, such as ion milling,
ECR etching, reactive ion etching, ion beam assisted etching, focused ion beam etching can be used. Particularly, in the present invention, since the gallium nitride based semiconductor laminated thin film has a small total thickness, one of the features is that these dry etching methods can be efficiently applied. As an electrode for injecting current,
Metals such as Al and In, tin oxide, indium oxide, tin oxide-indium oxide, zinc oxide, and degenerated ZnSe can be used, and these electrode layers are MBE method, vacuum evaporation method, electron beam evaporation method or sputtering method. And the like.

The element obtained by this method was cut with a dicing saw or the like, and wiring was performed using a gold wire with a wire bonder to produce an element. By applying a voltage of 7 V to the electrode of this device and injecting a current of 15 mA, 40 m
A blue emission of cd was observed.

[0026]

EXAMPLES The present invention will be described in more detail below with reference to examples.

[0027]

Example 1 An example in which a gallium nitride based semiconductor light emitting device is manufactured by the MBE method using ammonia will be described. A crystal growth apparatus provided with an evaporation crucible 2, 3, 4 and 5, a gas cell 6, and a substrate heating holder 7 in a vacuum container 1 as shown in FIG. 1 was used.

Ga metal is put in the evaporation crucible 2 to be 10
Heat to 20 ° C., put Mg metal into the evaporation crucible 4 and heat to 280 ° C., put Si into the evaporation crucible 5 and put 11
Heated to 00 ° C. I used amminia as gas,
A gas cell 6 having alumina fibers filled therein was used for introducing the gas, and the gas was supplied at a rate of 5 cc / min so that the gas was directly blown onto the substrate 8 by heating to 370 ° C.

As the substrate 8, a sapphire R surface having an off angle of 0.5 degree is used. The pressure in the vacuum container was 1 × 10 ⁻⁶ Torr during film formation. First, the substrate 8 is heated at 900 ° C. for 30 minutes and then maintained at a temperature of 750 ° C. to form a film. The film is formed by opening the shutter of the Ga crucible while supplying ammonia from the gas cell 6.
A film thickness of 20 at a film forming rate of 1.5 angstrom / sec.
A c-axis oriented gallium nitride semiconductor layer having a thickness of 00 angstrom was produced. An example in which RHEED was observed at an acceleration voltage of 30 kV and a current of 75 μA during the growth of a gallium nitride based semiconductor thin film (thickness: 1000 Å) is shown. The RHEED pattern is shown in FIG. 2, but a streak pattern can be observed when an electron beam is incident from the a-axis direction of gallium nitride, and a laterally spread line pattern is obtained when the electron beam is incident from the c-axis direction. It can be confirmed that the thin film is c-axis oriented. Then, 300 is deposited on the c-axis oriented gallium nitride semiconductor layer.
A 0 angstrom single crystal n-type gallium nitride semiconductor layer is formed, and a Ga shutter and M
Open the shutter of g, 200 Angstrom of M
A gallium nitride semiconductor laminated structure was produced by forming an i-type gallium nitride semiconductor layer doped with g. Then, an electrode for injecting a current is provided by performing a lithographic process on the laminated thin film. The lithography process can be performed by a process using a normal photoresist material, and as an etching method,
A window was formed to form an electrode for injecting a current by performing ion milling. Then, thickness 3000
An Angstrom Al electrode was formed by a vacuum deposition method.

The element obtained by this method was cut with a dicing saw, and wiring was performed using a gold wire with a wire bonder. FIG. 3 shows the device structure of the present invention, and FIG. 4 shows the results of measuring the diode characteristics. When a voltage of 7 V is applied to the electrode of this element and a current of 15 mA is injected, 40 mcd
Blue emission was observed. The emission spectrum is shown in FIG.

[0031]

Example 2 An example in which a gallium nitride based semiconductor light emitting device is manufactured by the MBE method using ammonia will be described. A crystal growth apparatus provided with an evaporation crucible 2, 3, 4 and 5, a gas cell 6, and a substrate heating holder 7 in a vacuum container 1 as shown in FIG. 1 was used.

Ga metal is put in the evaporation crucible 2 to be 10
Heat to 20 ° C and put In metal in the evaporation crucible 3 to 6
Heat to 60 ° C., put Mg metal in the evaporation crucible 4 and heat to 280 ° C., put Si in the evaporation crucible 5 and
Heated to 100 ° C. Ammonia is used as a gas, a gas cell 6 having alumina fibers filled therein is used for introducing the gas, and the gas is directly blown onto the substrate 8 by heating at 370 ° C. and supplied at a rate of 5 cc / min. did.

As the substrate 8, a sapphire R surface having an off angle of 0.5 degrees is used. The pressure in the vacuum container was 1 × 10 ⁻⁶ Torr during film formation. First, the substrate 8
A film is formed by heating at 00 ° C. for 30 minutes and then maintaining the temperature at 750 ° C. The film formation is performed by opening the shutter of the crucible of Ga, In and Si while supplying ammonia from the gas cell 6, and the film formation speed of 1.5 angstrom / sec.
A c-axis oriented n ⁺ -type gallium nitride based semiconductor layer doped with was prepared. Acceleration voltage 30k during growth of gallium nitride based semiconductor thin film (thickness 1000 angstrom)
As a result of observing RHEED at V and current of 75 μA,
A streak pattern can be observed when an electron beam is incident from the a-axis direction of gallium nitride, and a line pattern that is laterally widened when incident from the c-axis direction, confirming that the gallium nitride-based semiconductor thin film is c-axis oriented. be able to. Then, 500 on the gallium nitride based semiconductor layer.
An n-type single crystal gallium nitride semiconductor layer having a thickness of 0 angstrom was formed, and a shutter for Mg and a shutter for Ga and In were opened on the n-type single crystal gallium nitride semiconductor layer, and Ga _1-x In _x N doped with 300 angstrom of Mg was opened.
By forming a p-type gallium nitride based semiconductor layer having a composition of (x = 0.12), a gallium nitride based semiconductor laminated structure as shown in FIG. 6 was produced.

Next, an electrode for injecting a current is provided by subjecting the laminated thin film to a lithographic process. The lithography process can be performed by a process using an ordinary photoresist material, and a window for forming an electrode for injecting a current is formed by performing ion milling as an etching method. Then, an Al electrode having a thickness of 3000 angstrom was formed by a vacuum evaporation method.

The device obtained by this method was cut with a dicing saw, and wiring was performed using a gold wire with a wire bonder. Applying a voltage of 10V to the electrode of this element,
When a current of mA was injected, a green emission of 37 mcd was observed.

[0036]

Example 3 An example in which a gallium nitride based semiconductor light emitting device is manufactured by the MBE method using ammonia will be described. A crystal growth apparatus provided with an evaporation crucible 2, 3, 4 and 5, a gas cell 6, and a substrate heating holder 7 in a vacuum container 1 as shown in FIG. 1 was used.

Ga metal is put in the evaporation crucible 2 to be 10
Heat to 20 ° C., put Mg metal into the evaporation crucible 4 and heat to 280 ° C., put Si into the evaporation crucible 5 and put 11
Heated to 00 ° C. Ammonia is used as gas,
A gas cell 6 having alumina fibers filled therein was used for introducing the gas, and the gas was supplied at a rate of 5 cc / min so that the gas was directly blown onto the substrate 8 by heating to 370 ° C.

As the substrate 8, a sapphire R surface having an off angle of 0.5 degrees is used. The pressure in the vacuum container was 1 × 10 ⁻⁶ Torr during film formation. First, the substrate 8 is heated at 900 ° C. for 30 minutes and then maintained at a temperature of 750 ° C. to form a film. The film is formed by opening the shutter of the Ga crucible while supplying ammonia from the gas cell 6.
A film thickness of 20 at a film forming rate of 1.0 angstrom / sec.
A c-axis oriented gallium nitride semiconductor layer having a thickness of 00 angstrom was produced. RHEED was observed at an acceleration voltage of 30 kV and a current of 75 μA during the growth of the gallium nitride-based semiconductor thin film (thickness: 1000 Å). Then, since the line pattern spreads horizontally, it can be confirmed that the gallium nitride based semiconductor thin film is c-axis oriented.
Then, 3 is deposited on the c-axis oriented gallium nitride semiconductor layer.
A single crystal n-type gallium nitride semiconductor layer having a thickness of 000 angstroms is formed, and a Zn shutter is simultaneously opened with a Ga shutter to form a 500 angstrom Zn-doped p-type gallium nitride semiconductor layer. A gallium nitride semiconductor laminated structure as shown in 7 was produced.

Next, an electrode for injecting a current is provided by subjecting the laminated thin film to a lithographic process. The lithography process can be performed by a process using an ordinary photoresist material, and a window for forming an electrode for injecting a current is formed by performing ion milling as an etching method. Then, an Al-In electrode having a thickness of 3000 angstrom was formed by a vacuum evaporation method.

The element obtained by this method was cut with a dicing saw, and wiring was performed using a gold wire with a wire bonder. 15m by applying a voltage of 9V to the electrode of this element
When a current of A was injected, a blue-green light emission of 60 mcd was observed.

[0041]

Example 4 An example in which a gallium nitride based semiconductor light emitting device is manufactured by the MBE method using ammonia will be described. A crystal growth apparatus provided with an evaporation crucible 2, 3, 4 and 5, a gas cell 6, and a substrate heating holder 7 in a vacuum container 1 as shown in FIG. 1 was used.

Ga metal was put in the evaporation crucible 2 to be 10
Heat to 20 ° C., put Mg metal into the evaporation crucible 4 and heat to 280 ° C., put Si into the evaporation crucible 5 and put 11
Heated to 00 ° C. Ammonia is used as gas,
A gas cell 6 having alumina fibers filled therein was used for introducing the gas, and the gas was supplied at a rate of 5 cc / min so that the gas was directly blown onto the substrate 8 by heating to 370 ° C.

As the substrate 8, a sapphire R surface having an off angle of 0.5 degree is used. The pressure in the vacuum container was 1 × 10 ⁻⁶ Torr during film formation. First, the substrate 8 is heated at 900 ° C. for 30 minutes and then maintained at a temperature of 750 ° C. to form a film. The film formation was performed by opening the shutter of the crucible of Ga and Si while supplying ammonia from the gas cell 6 to form a c-axis oriented gallium nitride semiconductor layer having a film thickness of 4000 angstrom at a film forming rate of 1.0 angstrom / sec. . Acceleration voltage of 30 during growth of gallium nitride based semiconductor thin film (thickness 1000 Å)
As a result of RHEED observation at kV and current of 75 μA, a streak pattern can be observed when an electron beam is incident from the a-axis direction of gallium nitride, and a laterally widened line pattern is obtained when the electron beam is incident from the c-axis direction. Can be confirmed to be c-axis oriented. Subsequently, a 2000 angstrom single crystal n-type gallium nitride semiconductor layer is formed on the c-axis oriented gallium nitride semiconductor layer, and a Zn shutter is simultaneously opened with a Ga shutter to form a 1000 angstrom Zn nitride layer. A p-type gallium nitride semiconductor layer doped with is formed to form a gallium nitride semiconductor laminated structure as shown in FIG.

Next, an electrode for injecting a current is provided by subjecting the laminated thin film to a lithographic process. The lithography process can be performed by a process using an ordinary photoresist material, and a window for forming an electrode for injecting a current is formed by performing ion milling as an etching method. Then, an Al-In electrode having a thickness of 3000 angstrom was formed by a vacuum evaporation method.

The element obtained by this method was cut with a dicing saw, and wiring was performed using a gold wire with a wire bonder. 15m by applying a voltage of 9V to the electrode of this element
When the current of A was injected, a blue-green light emission of 100 mcd was observed.

[0046]

Example 5 An example in which a gallium nitride based semiconductor light emitting device is manufactured by the MBE method using ammonia will be described. A crystal growth apparatus provided with an evaporation crucible 2, 3, 4 and 5, a gas cell 6, and a substrate heating holder 7 in a vacuum container 1 as shown in FIG. 1 was used.

Ga metal is put in the evaporation crucible 2 to be 10
Heat to 20 ° C., put Mg metal into the evaporation crucible 4 and heat to 280 ° C., put Si into the evaporation crucible 5 and put 11
Heated to 00 ° C. Ammonia is used as gas,
A gas cell 6 having alumina fibers filled therein was used for introducing the gas, and the gas was supplied at a rate of 5 cc / min so that the gas was directly blown onto the substrate 8 by heating to 370 ° C.

As the substrate 8, a sapphire R surface having an off angle of 0.5 degree is used. The pressure in the vacuum container was 1 × 10 ⁻⁶ Torr during film formation. First, the substrate 8 is heated at 900 ° C. for 30 minutes and then maintained at a temperature of 750 ° C. to form a film. The film formation was performed by opening the shutter of the crucible of Ga and Si while supplying ammonia from the gas cell 6 to form a c-axis oriented gallium nitride semiconductor layer having a film thickness of 4000 angstrom at a film forming rate of 1.0 angstrom / sec. . Acceleration voltage of 30 during growth of gallium nitride based semiconductor thin film (thickness 1000 Å)
As a result of RHEED observation at kV and current of 75 μA, a streak pattern can be observed when an electron beam is incident from the a-axis direction of gallium nitride, and a laterally widened line pattern is obtained when the electron beam is incident from the c-axis direction. Can be confirmed to be c-axis oriented. Then, a 1000 angstrom single crystal n-type gallium nitride semiconductor layer was formed on the c-axis oriented gallium nitride semiconductor layer, and Ga and I were further formed thereon.
Open the Zn shutter at the same time as the n shutter and
Ga ₁₋ doped with 000 Å of Zn
A p-type gallium nitride semiconductor layer having a composition of _x In _x N (x = 0.20) is formed, and a Zn shutter is simultaneously opened with a Ga shutter to form a 1000 Å single crystal p-type gallium nitride semiconductor layer. To form a gallium nitride-based semiconductor laminated structure as shown in FIG.

Then, an electrode for injecting a current is provided by subjecting the laminated thin film to a lithographic process. The lithography process can be performed by a process using an ordinary photoresist material, and a window for forming an electrode for injecting a current is formed by performing ion milling as an etching method. Then, an Al-In electrode having a thickness of 3000 angstrom was formed by a vacuum evaporation method.

The element obtained by this method was cut with a dicing saw, and wiring was performed using a gold wire with a wire bonder. When a pulsed current was injected into the electrode of this device at 77 K, laser oscillation was confirmed at an injection current density of 200 A / cm ² or more. The emission wavelength is 430n
It was m.

[0051]

Comparative Example In the example, the temperature of the Ga evaporation crucible 2 was set to 1060 ° C., and the amount of ammonia introduced was 20 cc / mi.
A gallium nitride based semiconductor thin film was grown by the same method except that the growth rate was 25 angstroms / sec. Growth of gallium nitride based semiconductor thin film (thickness 100
0 angstrom), acceleration voltage 30kV, current 75μ
RHEED observation was performed in A. As a result, a random spot pattern was obtained, and it was considered that island-shaped growth had occurred.

[0052]

As a gallium nitride based semiconductor light emitting device according to the present invention, a device emitting blue light by current injection with a gallium nitride based semiconductor film thickness of 1 μm or less on a sapphire R-face substrate could be manufactured. In addition, since the film thickness is small, the process of manufacturing a light emitting device is easy and highly reliable, and the light extraction efficiency can be increased.

[Brief description of drawings]

FIG. 1 is a schematic view of a crystal growth apparatus used for thin film production.

FIG. 2 is a RHEED pattern photograph showing a crystal structure of a gallium nitride based semiconductor thin film.

FIG. 3 is a diagram showing a cross-sectional structure of a GaN light emitting device manufactured in Example 1.

FIG. 4 is a diagram showing diode characteristics of the GaN light emitting device manufactured in Example 1.

FIG. 5 is a diagram showing an emission spectrum of the GaN light emitting device manufactured in Example 1.

6 is a diagram showing a cross-sectional structure of a Ga _{1 -x} In _x N-based light emitting device manufactured in Example 2. FIG.

FIG. 7 is a view showing a cross-sectional structure of a GaN light emitting device manufactured in Example 3.

FIG. 8 c-axis GaN / n-GaN / p-GaN / n-G
It is a diagram showing the _{a 1-x In x N /} p -Ga 1-x In x N a light emitting device structure.

FIG. 9 c-axis Ga _1-x In _x N / n-Ga _1-x In _x N / p
-Ga is a diagram showing the _{1-y In y N (x} ≧ y) a light emitting device structure.

FIG. 10 c-axis Ga _1-x In _x N / n-Ga _1-x In _x N /
It is a diagram showing a _{p-Ga 1-y In y} N / p-Ga 1- x In x N (x ≦ y) a light emitting device structure.

[Explanation of symbols]

1 Vacuum Container 2 Evaporating Crucible 3 Evaporating Crucible 4 Evaporating Crucible 5 Evaporating Crucible 6 Gas Cell 7 Substrate Heating Holder 8 Substrate 9 Cryopanel 10 Valve 11 Cold Trap 12 Oil Diffusion Pump 13 Oil Rotary Pump 14 Shutter 15 Shutter 16 16 Shutter 17 Shutter 18 Sapphire R-plane substrate 19 c-axis oriented GaN layer 20 Single crystal n-GaN layer 21 Single crystal i-GaN layer 22 Al electrode 23 Single crystal n-Ga _1-x In _x N layer 24 Single crystal p-Ga _{1- x} In _x N layer 25 Single crystal p-GaN layer 26 c-axis oriented Ga _1-x In _x N layer 27 Single crystal p-Ga _1-y In _y N layer (x ≧ y) 28 Single crystal p-Ga _{1- y} In _y N layer (x <y)

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Kunio Miyata 1 2-2 Samejima, Fuji City, Shizuoka Prefecture Asahi Kasei Corporation

Claims (2)

[Claims] 1. An n-type single crystal gallium nitride based semiconductor layer having a c-axis oriented gallium nitride based semiconductor layer formed directly on a sapphire R-plane substrate having an off angle of 0.8 degrees or less. And gallium nitride having at least one light emitting layer formed of a p-type or i-type single crystal gallium nitride based semiconductor layer, and having an electrode at a desired portion for applying a voltage to the light emitting layer. -Based semiconductor light emitting device. 2. In the MBE method, a crystal growth apparatus having a gas source for supplying a nitrogen-containing gaseous compound and a solid source for supplying a group III element is used, and nitrogen is contained with a sapphire R surface as a substrate surface. Gaseous compounds and I
A step of forming a gallium nitride based semiconductor thin film oriented to the c-axis at a growth rate of 0.1 to 20 angstrom / sec by supplying a group II element, supplying a gaseous compound containing nitrogen and a group III element To form an n-type single-crystal gallium nitride-based semiconductor thin film, and to supply a gaseous compound containing nitrogen, a group III element and a p-type dopant to form a p-type or i-type single-crystal gallium nitride-based semiconductor thin film. A method for manufacturing a semiconductor light emitting device, comprising at least a forming step.