JPS59207897A - Gaseous phase epitaxial growth of thin film of single crystal of gallium arsenide phosphide - Google Patents

Abstract

PURPOSE:In subjecting successively a single crystal layer of GaP, a layer of GaAs1-xPx with a varable mixed crystal ratio and a layer of GaAs1-xPx with a constant mixed crystal ratio to gaseous phase epitaxial growth on the surface of single crystal substrate of GaP, to form a thin film of single crystal having improved crystallizability in high productivity, by carrying out the first single crystal growth of GaP under specific temperature conditions. CONSTITUTION:In forming the following single crystal of GaAs1-xPx on a single crystal substrate of GaP, in order to prevent occurrence of crystal defect between the crystals, first a thin film of single crystal of GaP is formed, a layer of GaAs1-xPx(0<x<=1) with a variable mixed crystal ratio changing continuously from 1 to a given value and a layer of it with a constant mixed crystal ratio are successively subjected to gaseous phase epitaxial growth. In subjecting the first single crystal of GaP to gaseous phase epitaxial growth, the temperature of the substrate is maintained at 850-980 deg.C at least starting 5-20min from the growth beginning, and after that, the temperature of the substrate is dropped at <=10 deg.C/min rate of temperature drop until it becomes 850-980 deg.C. A single crystal layer having improved crystallizability can be formed in high productivity.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for vapor phase epitaxial growth of gallium phosphide arsenide single crystal thin films.

Gallium arsenide phosphide, GaAs1-xPx (0(x≦
/) is gallium arsenide (GaAs) and gallium phosphide (
By changing the mixed crystal ratio (herein referred to as the above-mentioned value of Since it can be varied between 2 and 2 eV, it can be used to manufacture light emitting diodes of any color in the visible range (red to green).

Gallium arsenide phosphide is formed as a single-crystal thin film on a cap single-crystal substrate by a vapor phase epitaxial growth method that allows easy change of the mixed crystal.

In this case, the gallium arsenide phosphide single crystal layer film is applied to the substrate surface in order to reduce the occurrence of various crystal defects caused by the difference in lattice constant between the GaP substrate and the gallium arsenide phosphide single crystal layer. A mixed crystal ratio changing layer in which a GaP layer is formed and the mixed crystal ratio changes continuously from / to a desired value (for example, θ6 for an orange light-emitting diode, o, gs for a yellow light-emitting diode). ? It is formed to have a multilayer structure in which a layer having a constant mixed crystal content is formed in which the mixed crystal percentage is constant at a desired value. Note that the pn junction should be formed in a layer with a constant mixed crystal content.

As mentioned above, the gallium phosphide arsenide scientific crystal thin film has a rough structure, so its crystallinity is easily deteriorated, resulting in surface irregularities called pyramids and hillocks caused by localized abnormal growth. This was a major cause of a decrease in the yield of semiconductor components such as light emitting diodes.

In order to solve this problem, conventional methods include raising the substrate temperature to a high temperature (900C or higher), growing a portion of a single layer of GaP at high temperature, and then stopping the growth of the single crystal thin film and lowering the substrate temperature. There have been proposals for methods of restarting growth after reaching a certain temperature.

However, these methods have problems such as insufficient improvement of the surface condition and a decrease in productivity.

The present inventors have arrived at the present invention as a result of intensive research aimed at solving such problems.
A single crystal layer, a gallium arsenide phosphide mixed crystal single-change layer, and a gallium arsenide phosphide mixed crystal constant layer are formed in the above order to form a vapor phase epitaxial growth method for a gallium arsenide phosphide single crystal 7 film. During the vapor phase epitaxial growth of the GaP single crystal layer, the temperature of the single crystal substrate is kept at gso°C for at least the first S minutes after the start of the vapor phase epitaxial growth.
The temperature of the single crystal substrate is maintained at a constant temperature 1i in the range of ~qgo°C, and then the temperature of the single crystal substrate is maintained at a constant temperature 1i in the range of goo°C ~ 900°C while continuing the growth of the phosphide/gallium layer. Achieved by a method of continuously lowering the temperature to a constant temperature lower than the single crystal substrate temperature.

As a GaP single crystal substrate, (100) plane or (100
) A plane having an inclination of λ~10° with respect to the plane is suitable. Grow a GaP single crystal layer on a single crystal substrate. Ga
The thickness of the P single crystal layer is usually about 7 to 108 m.

The GaP layer is maintained at a temperature of gsθ°C to qgo°C, preferably qooc-qgo, for at least the first 6 minutes after the start of growth.
The temperature of the single crystal substrate is maintained at a constant temperature in the range c.

In this case, changing the heating temperature of the substrate is not preferable because the crystallinity of the GaP layer deteriorates.

Further, the temperature of the single crystal substrate is preferably maintained at the above temperature for at least the first S minutes, preferably 5 to 0 minutes, after the start of the vapor phase epitaxial growth of the GaP layer. If the time is less than S minutes, the effects of the present invention will not be exhibited. The holding time is not particularly limited as long as it is S minutes or more, but from the viewpoint of productivity etc., it is preferably about 20 minutes or less. The substrate temperature is q
If the growth rate 1y of the GaP layer exceeds gs
If it is less than oc, the crystallinity deteriorates and is not preferable.

Subsequently, the substrate is grown while continuing to grow the GaP layer.

After the temperature of the single crystal substrate reaches a temperature in the gooc-qooc range and lower than the above-mentioned initial temperature, if necessary, the GaP single-crystal layer is heated at the above-mentioned predetermined temperature until it reaches a predetermined thickness. GaP) Grow Oj.

The gas composition used for the growth of the GBp layer is Ga.
HCL PH3H2 system is preferred, but Ga-PH3H2
A Ga (CH3)3 PH3H2 system may be used.

In this case, the grown Ga
This is not preferable since the crystallinity of PJffj deteriorates and the growth rate decreases when the qooc is exceeded. In addition, even if the temperature of the single crystal substrate is initially maintained at a high temperature and the growth rate is low,
By forming a GaP layer with good crystallinity, and then maintaining it at a lower temperature to obtain a higher growth rate, after the growth of the low-productivity GaP single crystal layer is completed, it is mixed by a known method. The crystallinity X is /
A gallium arsenide phosphide mixed crystal whose mixed crystal ratio is constant at the predetermined value is then grown in a vapor phase to a thickness of about 70 to 50 μm. Grow a constant rate layer of about 20 to 100 μm. The above-mentioned constant J-type mixed crystal ratio is selected to be a constant value in the range of 0 (x≦/, preferably in the range of O5≦X≦/).

In the case where a pn junction is formed in the above-mentioned constant layer, and the gallium arsenide phosphide forming the above-mentioned constant layer is an indirect transition type (
θdaS≦X≦7) is doped with nitrogen as an isoelectronic trap.

The gas composition used to grow the gallium arsenide phosphide layer is:
The Ga-HCl-PH3-AsH3-H2 system is suitable;
In addition, G a P Cl3 A s Cl3 H2 system, G
a (CH3)3 PH3AsH3 system etc. may also be used.

According to the method of the present invention, no protrusions or the like due to local abnormal growth are observed on the surface of the obtained gallium phosphide arsenide single crystal thin film, and productivity does not decrease. Moreover, the brightness of the light emitting diode obtained using the single crystal thin film is also high (the industrial value is high).

The method of the present invention will be explained in more detail based on Examples.

Example 1 According to the method of the present invention, yellow color (approx. peak emission wavelength!, -g g
OX±2 o'X) G'aA 80 for light emitting diode
．． A 15P0.85 single crystal thin film was formed on a GaP single crystal substrate as follows.

First, λ×1017 atoms/crd of sulfur (S) is added as an n-type impurity, and GaP has a crystallographic plane that is deviated from the (10o) plane by about 0° in the /10〉 direction.
A single crystal substrate was prepared.

The GaP single crystal substrate was initially approximately 360 μm thick, but was subjected to a degreasing process using an organic solvent followed by mechanical-chemical polishing.
A thickness of 300 μm was obtained by the lish-ing process.

Next, the polished GaP single crystal substrate and the quartz boat containing high-purity UCa were placed at predetermined locations in a horizontal quartz epitaxial reactor with an inner diameter of 70 rra and a length of 1 oocn'+. Argon (Ar) is introduced into the epitaxial reactor to sufficiently replace and remove air, and then ultra-high-intensity hydrogen gas (H2> w
, 3 o o o cc per minute was introduced, the flow of Ar was stopped, and the temperature raising process began.

The temperatures of the Ga-containing quartz port set region and the GaP single crystal substrate seven-layer region are 30°C and 930°C, respectively.
After confirming that the temperature was maintained, vapor phase growth of a GaAso-+sPo, ss single crystal thin film for a yellow light emitting diode was started.

From the start of vapor phase growth, hydrogen sulfide (H2S), an n-type impurity, diluted with nitrogen gas to humidity/Oppm was added at a rate of 6/min.
cc was introduced, while high purity hydrogen chloride gas (
By introducing 1.0 cc of Hct) per minute and reacting with Gaε, 5 generates 100% QaCt φ. On the other hand, hydrogen phosphide (PH3) diluted with H2 and having a humidity of 10% is introduced every minute. 2A'ACC was introduced, and the first GaP single crystal layer was formed on the GaP single crystal substrate while maintaining the growth temperature (corresponding to the substrate temperature) at 930° C. for the first 70 minutes.

For the next 20 minutes, only the growth temperature was gradually lowered by IS4 from 930C to GGOC without changing the flow rate of each gas to form a second GaP single crystal layer.

For the next 60 minutes, the concentration of hydrogen arsenide (AsH3) diluted with H2/θ is maintained at a constant ζ growth temperature of ggoc.
is gradually increased from Occ to 3 Acc per minute, and together with each of the above gas flows, a third layer, that is, a gallium phosphide arsenide mixed crystal ratio changing layer (GaP-+GaAs>1
5P (6B5) was grown.

For the next 30 minutes, without changing the flow rate of each gas, i.e.
H2, ■(2S,, HCt1PH3 and A a H3
30-00 cc, 4cc, and Occ per minute, respectively.
2AIIcc and 3bcc were introduced to grow the first layer, ie, G'A sO,+S Po, 85 single crystal layer.

Next, for the final 40 minutes, in addition to the epitaxial layer formation conditions of G.
Introducing cc and nitrogen (N)? A fifth layer doped as an isoelectronic trap, namely Ga
A so, 15 PO, 85 single crystal layer (N concentration gx/
Q18r:)l-3) was grown.

The surface condition of the epitaxial wafer after being taken out was extremely good, and no protrusions or other surface defects were observed.

Epitaxial multilayer r14 obtained as above
As a result of various physical property measurements and analysis,
, the layer thicknesses of the second, third, third, and fifth epitaxial layers are respectively) z 2 μm 1 μm! μm17g, 3μm
, 10.2μm, /'gOμm.

In addition, the n-type carrier suppression is approximately N3X/C16('
7n-3, gOX 1015 cm-3 in the nitrogen-doped fifth epitaxial layer region.

? A yellow light-emitting diode was prepared using the above-mentioned monocrystalline epitaxial wafer (the name for the composite of the epitaxial layer and the substrate).
The brightness value (light output) was actually measured.

That is, a 6 yen erectile wafer is mixed with a P-type impurity and 1 to 100 g of zinc arsenide, ZnAs2-2! i m! 7 and vacuum sealed in a high purity quartz ampoule at temperature gq; b.

Impurity thermal diffusion was performed at °C. The resulting n-junction depth was 3 μm from the surface. The back side (
A yellow light emitting diode tip was created by putting it into a series of device production lines including the substrate polishing process, electrode forming process, wire honing process, and -Z hit.

t/ic, light emitting diode chip (chip area size and P/n junction area size are both !00μzXs
DC current density, 20A/C
A current of 7 d was applied, and the brightness value (light output) was measured under the condition that the chip was not coated with epoxy resin. As a result, at a peak emission wavelength of 5gg0A±/5A, the brightness value was /
l-300Ft, -L-3,300Ft, -L, average s
/, xoFt-r.

Example The same equipment as used in Examples was used.

Q & A, S for orange light emitting diode based on the present invention
An O,35P(lj15) single crystal thin film was formed on a GaP single crystal substrate.

That is, Example/ I cleaned the Vt calendar in the same way.

From the start of vapor phase growth, H2S gas was dispersed with nitrogen gas at a concentration/Oppm of 3000 CC per minute, and H2 as a carrier gas was added at 3000 CC per minute.
HCt for C1 formation is occ per minute, 70% PH3 as V group component is once per minute/'''/3cc, 7CtL.
While introducing it into the epitaxial reactor, the growth temperature (equivalent to the substrate temperature IVC) 'K qa.

The first GaP single crystal layer was formed over a period of 70 minutes while maintaining the temperature at .degree.

Next, 2! For i minutes, while maintaining the flow rate of each gas at '&2, i.e., I(2, H2S, I-ICt+PH3, respectively, for iy minutes, 3000cc, Acc, Occ, /9
! ; While introducing a constant amount of cc, the growth temperature was changed from 930°C to g
s.

A second GaP single crystal layer was formed while gradually lowering the temperature at a temperature of .degree.

For the next 70 minutes, the growth temperature was kept constant at gso°C, and H2, H2S, HCL, and PH3 were added at a rate of 3000/min.
CC1 Occ, Otsu Occ and /93cc while maintaining a constant view, A s H3 only from Occ to 10Scc per minute
A third gallium arsenide phosphide mixed crystal ratio variable layer (GaP −+ caAsO, 35p0.
65) was formed.

For the next 30 minutes, keep the crystal growth temperature at gsoc, and
(2, H,, S, HCl, PH3 and As
H3"; i 3000cc, 6cc, Otsu O, respectively
CC, /93CC and /0, while keeping S-cc constant, the Q a A So of the conduit, 35 PO,6
5. A constant amount of mixed crystals was formed.

For the next 75 minutes, the growth temperature was kept constant at 5-0' IC, and H2,T(2S, J(Ct, PH
3-row K ASH3' (each 3000cc/min,
6cc, bOcc, /93cc and /θS While maintaining CC constant, newly add NH3'(< bt, min, 25
Added θcc, G a A 80.75 PO, 6
5 Constant black rate (Nm 1 degree l x 7019 saw-3). The surface condition of the epitaxial wafer obtained was very good, and no protrusions or other surface defects were observed.

The thickness of each of the first, second, third, and third epitaxial layers formed as described above was 37 μm.
m, 3-, 311m, 2! r 2μm, 90μm
,/! r, gμm.

Next, an orange light-emitting diode with an epitaxial unihull having a missing circle was fabricated according to the direction described in Fuseta Example, and the luminance was measured at 11f.

As a result, the light emitting diode chip (chip area size and P/n junction area size are both i/n) in this example.
j j 00 μm x 500 μm square), the brightness value is 3000 Ft-
L~3SOOFL-L, average 3300 Ft4. It was.

The peak emission wavelength was 3θOX±20X.

=547-

Claims (1)

[Claims] A gallium arsenide phosphide single crystal layer, a gallium arsenide phosphide mixed crystal ratio variable layer, and a gallium arsenide phosphide mixed crystal ratio constant layer are formed in the above order on a gallium phosphide single crystal substrate to produce gallium arsenide phosphide. In the vapor phase epitaxial growth method of the monocrystalline layer, when the gallium phosphide single crystal layer is vapor phase epitaxially grown, at least the initial S
The temperature of the single crystal substrate is maintained at a constant temperature in the range of gso°C to 900°C for a few minutes, and then the temperature of the single crystal substrate is maintained at a constant temperature in the range of goo°C to 900°C while continuing the growth of the gallium phosphide layer. A method characterized by continuously lowering the temperature to a constant temperature lower than the single crystal substrate temperature.