JP2003257880A - Light-emitting device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an InGaN with high quality and excellent crystallinity. <P>SOLUTION: An indium gallium nitride semiconductor (InXGa<SB>1-</SB>XN; 0<X<0.5) is formed on a substrate. The indium gallium nitride semiconductor is composed of a single crystal in which Si or Ge is doped in the range of 10<SP>18</SP>to 10<SP>20</SP>/cm<SP>3</SP>via a buffer layer grown at low temperatures and a GaN layer or an AlGaN layer grown on the buffer layer. <P>COPYRIGHT: (C)2003,JPO

Description

DETAILED DESCRIPTION OF THE INVENTION [0001] The present invention relates to a blue light emitting diode.
Nitride used in silicon nitride, blue laser diodes, etc.
Umgallium semiconductor and its growth method
is there. [0002] 2. Description of the Related Art Blue diodes and blue laser diodes
Gallium nitride as a practical semiconductor material used for
(GaN), indium gallium nitride (InGa)
N), nitrogen such as gallium aluminum nitride (GaAlN)
Gallium arsenide-based compound semiconductors are attracting attention.
InGaN also has a band gap of 2 eV to 3.4 eV.
Is very promising. Conventionally, metal organic chemical vapor deposition (hereinafter referred to as MOCV)
It is called the D method. When InGaN is grown by
Long temperature 500 ° C to 600 ° C, on sapphire substrate
Was growing up. Because the melting point of InN is about 5
Since the melting point of GaN is about 1000 ° C.
When InGaN is grown at a high temperature of 600 ° C. or more,
The decomposition pressure of InN in GaN is about 10 atm or more.
InGaN is almost completely decomposed and formed
Only deposits of Ga metal and In metal
It is because. Therefore, grow InGaN
If you try to keep the growth temperature low
won. [0004] SUMMARY OF THE INVENTION Under such conditions,
The crystallinity of the grown InGaN is very poor.
Even if photoluminescence measurement is performed at temperature,
Light is hardly seen, and light emission from deep levels is slightly
Only blue light emission was observed.
won. In addition, X-ray diffraction detects InGaN peaks
Almost no peak was detected, and the crystal
Properties are closer to amorphous crystals rather than single crystals
This was the actual situation. [0005] Blue light emitting diode, blue laser diode
In order to realize blue light emitting devices such as
Of InGaN with excellent crystallinity
Is desired. Therefore, the present invention should solve this problem.
The purpose of the product is
InGaN with excellent crystallinity and its growth method
Providing excellent light-emitting devices.
And [0006] [MEANS FOR SOLVING THE PROBLEMS]
For example, the indium gallium nitride semiconductor according to the present invention is:
A GaN layer or an AlGaN layer to be next grown on the substrate
Buffer layer grown at a low temperature
Formed through the grown GaN layer or AlGaN layer
10 Si or Ge¹⁸-10²⁰/ Cm^ThreeRange of
Indium Gallium Nitride Consisting of Single Crystals Doped with Air
Semiconductor (In_XGa_1-XN, 0 <X <0.5).
Further, the light emitting device according to the present invention can be grown next on a substrate.
Grown at a lower temperature than the GaN or AlGaN layer to be grown
Buffer layer and GaN grown on the buffer layer
Layer or AlGaN layer and its GaN layer or AlGaN layer
Indium gallium nitride semiconductor (In
_XGa_1-XN, 0 <X <0.5)
Wherein the indium gallium nitride semiconductor is Si
Or Ge is 10¹⁸-10²⁰/ Cm^ThreeDoped in the range
Characterized by being made of a single crystal. That is,
Akira said that when growing InGaN by MOCVD,
Nitrogen is used as the carrier gas for the source gas.
GaN or GaAlN instead of on sapphire
At a temperature higher than 600 ° C
Can be grown with excellent crystallinity, and in addition,
Its crystallinity and properties
Has been found to be significantly improved
It is. [0007] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The growth method of the present invention uses MOCVD.
Of Indium Gallium Nitride Compound Semiconductor Growth Method
Gallium source gas and
Gas of the source of nitrogen, gas of the source of nitrogen, and gas of the source of silicon
Or a source gas of germanium, and
Growth above 600 ° C using nitrogen as carrier gas
At a temperature, Si or Ge is doped on the gallium nitride layer.
General formula In_XGa_1-XN (where X is 0 <X <0.5)
The indium gallium nitride semiconductor represented by
It is characterized by the following. In the growth method of the present invention by MOCVD,
The source gas contains, for example, trimethyl gas as a Ga source.
Li @ Ga (CH_Three)_Three: TMG｝, triethyl galliu
Mu @ Ga (C_TwoH_Five)_Three: TEGII, Ammo as nitrogen source
Near (NH_Three), Hydrazine (N_TwoH_Four), Indium source
As trimethylindium @ In (CH_Three)_Three: TM
I}, triethylindium {In (C_TwoH_Five)_Three: TE
I｝, silane (SiH_Four), Germanium
German source (GeH_Four) Etc.
Can be. Further, the carrier gas for the raw material gas is used as a carrier gas.
The growth temperature is higher than 600 ° C. by using nitrogen.
Even if the InN in InGaN is decomposed and in the crystal lattice
Can be suppressed. Indium in raw material gas supplied during growth
The molar ratio of indium in the source gas was 1 gallium to 1 gallium.
Preferably at least 0.1, more preferably at least 1.0
adjust. When the molar ratio of indium is less than 0.1,
It is difficult to obtain a mixed crystal of InGaN, and the crystallinity tends to deteriorate.
In the direction. Because the growth method of the present invention
Because InGaN is grown at a high temperature,
InN decomposition occurs. Therefore, InN in GaN crystal
Because it is difficult to enter
By supplying a large amount of indium, InN can be converted to GaN.
Can be placed in the crystal. Therefore, the indium model
It is preferable that the ratio increases as the temperature increases.
For example, at a growth temperature of around 900 ° C.,
The X value is set to 0.1 by supplying about 10 to 50 times of the system.
In x Ga 1 -xN less than 5 can be obtained. If the growth temperature is higher than 600 ° C.
Well, preferably in the range of 700 ° C or more and 900 ° C or less
adjust. If the temperature is lower than 600 ° C., GaN crystals grow
InGaN crystals are difficult to form
Even in this case, InGaN becomes poor in crystallinity as in the related art.
If the temperature is higher than 900 ° C., InN is decomposed and
InGaN tends to become GaN
is there. The molar ratio of the indium gas supplied and the growth temperature
The degree is the target In_XGa_1-XX value of N 0 <X <0.5
Can be changed as appropriate. For example, let's increase In
If it grows at low temperature around 650 ° C,
The molar ratio of In in the source gas may be increased. Lots of Ga
If you try to grow at a high temperature around 900 ℃
Good. However, at temperatures higher than 600 ° C
In 0.5 or more_XGaN_1-XTo grow N
InXG which is very difficult and has an X value of 0.5 or more
a1-XN was used for light emitting devices such as light emitting diodes
In this case, the emission wavelength is in the yellow region, blue and ultraviolet.
X value should be less than 0.5
The reason was limited. FIG. 2 is a view showing a supply method in the growth method of the present invention.
Of Si and the resulting Si-doped InGaN
FIG. 4 is a diagram illustrating a relationship between luminescence intensities. This is
2 liters / min of nitrogen as rear gas, as raw material gas
2 × 10 TMG^-6Mol / min, TMI 20 × 10^-6Mo
/ Min, NH3 is supplied at 4 liter / min.
In order to dope, the supply amount of silane gas is changed to
In doped with Si on N layer_0.25Ga_0.75Grow N
And after growth, the resulting Si-doped In_0.25Ga _0.75N layer
Was irradiated with a 10 mW He-Cd laser, and 45
The photoluminescence intensity at 0 nm was measured.
It is. Note that this figure shows the Si formed on the GaN layer.
Not doped with In_0.25Ga_0.75N-layer photoluminescence
The relative intensity when the sense intensity is 1 is shown. This
In which does not dope Si_0.25Ga_0.75Photoluminescence of N
FIG. 4 shows the spectrum of the luminescence. Aside from this,
The Si-doped In of the present invention_0.25Ga_0.75N's photo
FIG. 5 shows the luminescence spectrum. As shown in FIG.
InGaN photoluminescence intensity is dramatically increased
Increase. The molar ratio of silicon in the source gas to gallium 1
1 × 10^-FiveBy adjusting it to the range of ~ 0.05
The strength is 5 times higher than that without Si doping.
And more than 60 times the maximum. FIG. 3 also shows the supplied Ge and the obtained Ge.
Ge-doped In_0.25Ga_0.75N photoluminescence
It is a figure which shows the relationship of intensity | strength. This is also a carrier gas
Nitrogen at 2 liters / minute and TMG as raw material gas at 2 ×
10^-6Mol / min, TMI 20 × 10^-6Mol / min, NH
3 at 4 liters / min under the same conditions as above,
By changing the supply amount of germane gas to dope Ge,
Ge doped In on GaN layer_0.25Ga_0.75N
After growing and growing, the resulting Ge-doped In_0.25Ga_0.75
The photoluminescence intensity at 450 nm of the N layer
Measured. This figure also shows the shape on the GaN layer.
No dope In_0.25Ga_{0. 75}N-layer photo
Indicated by relative intensity when the luminescence intensity is set to 1.
I have. In FIG. 3, as in FIG.
Therefore, the photoluminescence intensity of InGaN is dramatically increased.
And the molar ratio of germanium in the source gas
1 × 10^-FourBy adjusting to ~ 0.5
The strength is 5 times higher than that without Si doping.
More than doubled, up to 60-70 times
You can see that Growing InGaN as described above
As a result, 10% of Si or Ge¹⁶/
cm^Three-10^{twenty two}/cm^ThreeCan be doped. Photole
From the luminescence results, the optimal value is 10¹⁸-10²⁰
/cm^ThreeIt is. According to the growth method of the present invention, the carrier
Growth temperature higher than 600 ° C by using nitrogen as gas
In the degree, decomposition of InGaN can be suppressed,
Even if InN is decomposed to some extent, indium in the source gas
Supply high quality to obtain high quality InGaN
Can be. Furthermore, conventionally, I
While growing nGaN layer, sapphire and InGa
Since the lattice constant mismatch with N is about 15% or more,
It is considered that the crystallinity of the obtained crystal deteriorates. on the other hand,
In the present invention, it is grown on a GaN or GaAlN layer
Thereby, the lattice constant irregularity is reduced to 5% or less.
To form InGaN with excellent crystallinity.
Can be FIG. 4 shows InG grown on the GaN layer.
aN, which is remarkably expressed, and in the conventional method,
The photoluminescence spectrum of InGaN is completely
Although measurement could not be performed, crystallinity was clearly improved in the present invention.
Emission peak in the 450 nm blue region.
Have been. In the growth method of the present invention, the Ga
A part of Ga of N may be replaced by Al.
is there. Further, doping with Si and Ge
Photoluminescence compared to undoped
It is possible to dramatically increase the sense intensity from 5 to 70 times.
Wear. This is due to the crystallinity due to the effect of Si and Ge,
This is a significant indication that quality has been improved. FIG.
FIG. 4 is a diagram showing this, and the spectrum is shown in a range of 1/50 of FIG.
This is a measurement of
You can see that. [0021] BRIEF DESCRIPTION OF THE DRAWINGS FIG.
Is explained in detail. FIG. 1 shows the MOC used in the growth method of the present invention.
FIG. 2 is a schematic cross-sectional view showing a configuration of a main part of the VD device,
Shows the structure of the reactor and the gas system diagram that communicates with the reactor.
ing. 1 is a counter connected to a vacuum pump and an exhaust device.
Reaction vessel, 2 is a susceptor for mounting a substrate, 3 is a susceptor
Heater for heating the heater, 4 rotates the susceptor, moves up and down
The control axis to be moved, 5 is inclined or horizontal to the substrate
Nozzle for supplying raw material gas to the nozzle, 6 based on inert gas
By feeding the gas vertically toward the plate,
It acts on the plate surface to bring the source gas into contact with the substrate.
The conical quartz tube 7 is a substrate. TMG, T
The source of organometallic compounds such as MI is a trace amount of bubbling gas
Doping gas such as silane and germane
The reaction volume is controlled by the carrier gas
Supplied inside the vessel. Example 1 First, sapphire was thoroughly cleaned.
A Set the substrate 7 on the susceptor 2 and
Is enough to replace. Next, while flowing hydrogen from the quartz nozzle 5,
Raise the temperature to 1050 ° C with heater 3 for 20 minutes
The sapphire substrate 7 is held and cleaned. Subsequently, the temperature is lowered to 510 ° C.
Ammonia (NH_Three)₄Liters / minute and key
While flowing hydrogen at 2 liters / minute as carrier gas,
TMG 27 × 10⁻⁶Flow for mol / min and hold for 1 minute
Growing GaN buffer layer to about 200 Å
You. During this time, 10 hydrogen was supplied from the conical quartz tube 7.
Liters / minute and nitrogen at 10 liters / minute
And slowly rotate the susceptor 2. After the growth of the buffer layer, only TMG is stopped,
Increase temperature to 1030 ° C. The temperature reaches 1030 ° C
If TMG is used as a carrier gas,
× 10⁻⁶Grown at a flow rate of 30 mol / min for 30 min.
The layer is grown 2 μm. After growing the GaN layer, the temperature is increased to 800 ° C.
Switch the carrier gas to nitrogen and use 2 liters of nitrogen /
Min, TMG is 2 × 10^-6Mol / min, TMI 20 × 10
^-6Mol / min, 2 × 10^-9Mol / min, ammo
While flowing near at 4 L / min.
The aN layer is grown for 60 minutes. During this time, conical
The gas supplied from the quartz tube 7 is only nitrogen,
Continue to flow at liters / minute. The InGaN layer obtained as described above
Taking the X-ray rocking curve, In_0.25Ga_0.75N
It has a peak where the composition is shown, and its half width is
6 minutes. This value of 6 minutes has been reported previously
Of the InGaN according to the method of the present invention.
It shows that the crystallinity is very good. Also, S
When Si in InGaN was measured by IMS,
2 × 10¹⁹/cm^ThreeMet. Example 2 After the GaN layer was grown, TMG was
× 10^-6Mol / min, TMI 20 × 10^-6Mol / min,
2 × 10^-8Except for flowing at mol / min.
Similarly, a Ge-doped InGaN layer was grown. He-Cd laser is applied to the obtained InGaN layer.
When the photoluminescence is measured by irradiating
It has an emission peak at 450 nm and is X-ray locking
When the curve is measured, In_0.25Ga_0.75Shows the composition of N
However, it has a peak and its half width is also 6 minutes.
Met. The Ge concentration in InGaN is about 1 ×
10¹⁹/cm^ThreeMet. Example 3 After growing the GaN layer, the TMI was increased to 2
× 10^-7Except for the flow at mol / min, S
An i-doped InGaN layer was grown. X-ray rocking force of the obtained InGaN layer
When the probe is measured, In_0.08Ga_{0. 92}The composition of N
It had a peak at that time, and its half width was 6 minutes.
Was. In addition, irradiation of He-Cd laser
When the luminescence was measured, a strong purple In at 390 nm was observed.
Inter-band light emission of GaN was observed. [Embodiment 4] Growth of buffer layer of Embodiment 1
After that, stop only TMG and raise the temperature to 1030 ℃
You. When the temperature reaches 1030 ° C, carry hydrogen again.
54 × 10 TMG as Agus⁻⁶Mol / min, TMA
To 6 × 10^-6Grown at a flow rate of 30 mol / min for 30 min.
_0.9Al_0.1Same as Example 1 except that the N layer is grown by 2 μm
Then Ga_{0. 9}Al_0.1Si doped InGaN on N layer
Layers were grown. As a result, X of the obtained InGaN layer
The line rocking curve is also In_0.25Ga_0.75Set of N
The peak has a peak at a point where
Minutes. The Si concentration was 2 × 10¹⁹/cm^ThreeSame as
there were. [0033] According to the growth method of the present invention, conventionally,
It was possible to grow single crystals of InGaN layer
Can be grown by doping with Si and Ge.
And its crystallinity and quality can be further improved.
You. Therefore, practical InGaN can be obtained by the present invention.
Because it will be stacked in a blue light emitting device to be developed in the future
The conductor material can be made into a double heterostructure, and a blue laser die
Aether becomes feasible, and its industrial utility value is great.
No.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 shows an MO used in an embodiment of the growth method of the present invention.
FIG. 2 is a schematic cross-sectional view illustrating a configuration of a main part of the CVD apparatus. FIG. 2 shows the supplied Si and the growth method according to the present invention;
The figure which shows the relationship of the photoluminescence intensity of the obtained Si doped InGaN. FIG. 3 shows the supplied Ge and the growth method according to the present invention;
The figure which shows the relationship of the photoluminescence intensity of the obtained Ge doped InGaN. FIG. 4 shows InGa obtained in the process of one embodiment of the present invention.
The figure which shows the spectrum by the photoluminescence measurement of N. FIG. 5 is a diagram showing a spectrum by photoluminescence measurement of InGaN according to one embodiment of the present invention. [Description of Signs] 1 ... reactor vessel, 2 ... susceptor, 3 ... heater, 4 ... control shaft, 5 ... quartz nozzle, 6 ... conical quartz tube, 7 ... substrate.

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Claims (1)

Claims 1. A GaN layer or AlGaN layer grown on a substrate at a lower temperature than a GaN layer or AlGaN layer to be grown next and a GaN layer or AlGaN layer grown on the buffer layer. Formed of Si or Ge is 10 ¹⁸ to 10
²⁰ / doped in the range of cm ³ has been indium gallium nitride semiconductor made of monocrystalline _{(In X Ga 1 -X N,} 0 <X <
0.5).