JPH10270751A - Epitaxial wafer for light-emitting semiconductor device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a wafer highly intensified by specifying boron concentration in an n-type GaP single-crystal substrate of an epitaxial wafer for light-emitting semiconductor device, which is constituted by forming at least an n-type semiconductor epitaxial layer and a p-type semiconductor epitaxial layer on the n-type GaP single-crystal substrate. SOLUTION: There is a correlation between boron (B) concentration in an n-type GaP single-crystal substrate and brightness. On the n-type GaP single- crystal substrate 1 in which carrier concentration is uniform and B concentration is not, and n-type GaP epitaxial layer 2 and a p-type GaP epitaxial layer 3 are formed in the same process, to manufacture an epitaxial wafer. In the correlation between the luminance and the boron (B) concentration in the n-type GaP single-crystal substrate, B concentration is 1×10<17> cm<-3> or below, preferably 5×10<16> cm<-3> or below, and the epitaxial wafer of high luminance and less luminance variation is obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention
The present invention relates to an epitaxial wafer for an sP-based and AlGaInP-based light-emitting semiconductor device, and more particularly to an epitaxial wafer that provides a light-emitting semiconductor device with high luminance and little luminance variation.

[0002]

2. Description of the Related Art Visible light-emitting diodes are widely used in various display devices and the like because of their low power consumption and long life. In particular, both applications and usage have been increasing due to high luminance due to recent technological improvements and diversification of luminescent colors due to the introduction of new crystalline materials. Among these light emitting diodes, those using a GaP single crystal substrate as a substrate include GaP-based, GaAsP-based, and AlG-based.
There is an aInP-based light emitting diode.

As a GaP-based light emitting diode, red,
There are three types of light emitting diodes, yellow green and pure green, all of which are manufactured by liquid phase epitaxial growth. Since GaP is an indirect transition, the luminance of red and yellow-green light emitting diodes is increased by introducing a light emission center. The red light emitting diode has a structure in which an n-type GaP epitaxial layer and a p-type GaP epitaxial layer doped with zinc (Zn) and oxygen (O) are formed on an n-type GaP single crystal substrate. Zn-O pair emits red light having an emission wavelength of about 700 nm. The yellow-green light emitting diode is provided on an n-type GaP single crystal
After forming the aP buffer layer, an n-type GaP epitaxial layer and an n-type Ga
It has a P epitaxial layer and a p-type GaP epitaxial layer, and emits yellow-green light having an emission wavelength of about 570 nm. Pure green light emitting diode is n-type GaP
An n-type GaP buffer layer is formed on a single crystal substrate as needed, and then an n-type GaP epitaxial layer and a p-type GaP epitaxial layer not doped with N are formed. Although the luminance is lower than that of the yellow-green light emitting diode, pure green light with a light emission wavelength of about 555 nm can be obtained.

[0004] GaAsP-based light emitting diodes are manufactured by a vapor phase epitaxial growth method. GaP and GaAsP
Are different from each other on the n-type GaP single crystal substrate.
First, an n-type GaAsP composition gradient layer is formed by a vapor phase epitaxial growth method, and then an n-type GaAsP composition constant layer is similarly formed by a vapor phase epitaxial growth method.
By diffusing Zn to the surface of the AsP constant composition layer, p
An n-junction is formed. By changing the composition of As and P in the n-type GaAsP constant composition layer, red (about 660 nm)
Luminescent color from yellow to about 590 nm through orange (about 610 nm). In addition, when the composition of P is high, an indirect transition occurs, so that N is doped as the emission center to increase the luminance.

[0005] AlGaInP-based light emitting diodes are mainly manufactured by metal organic chemical vapor deposition (MOCVD). Usually, a GaAs single crystal substrate is often used,
It can also be manufactured using a GaP single crystal substrate. Ga
Since the band gap of As is smaller than the band gap of AlGaInP, which is the active layer, light emission is absorbed.
Since aP has a larger band gap than AlGaInP, it does not absorb light emission. Therefore, when GaP is used as the substrate, there is an advantage that light emitted from the active layer to the substrate side is not absorbed and high luminance is obtained. When GaP is used as a substrate, since the lattice constants of GaP and AlGaInP are different, a composition gradient layer of InGaP or AlGaInP or AlInP is first formed on an n-type GaP single crystal substrate by MOCVD, and then n-type AlG is formed by MOCVD.
aInP cladding layer, AlGaInP active layer, p-type Al
A GaInP cladding layer is formed, and if necessary, a contact layer or a window layer is further formed thereon. The cladding layer may be made of AlInP. GaAs, GaAlAs, GaP or the like is usually used as a crystal of the contact layer or the window layer, and other growth methods such as a vapor phase epitaxial growth method may be used in addition to MOCVD as a growth method of these layers. it can. AlGaInP-based light emitting diodes are made of AlGaI
By changing the crystal composition of the nP active layer, 640 nm
Light emission from about red to about 550 nm through orange and yellow can be obtained.

The above-mentioned GaP system, GaAsP system and Al
GaInP-based light emitting diodes are all Te, Si
It is manufactured using an n-type GaP single crystal substrate using such as a dopant.

[0007]

Although the brightness of these light-emitting diodes has been improved by recent technological improvements,
The market demands higher brightness. Further, as the application to a large-sized display or the like is widened, a demand for reduction in luminance variation is increasing. An object of the present invention is to provide an epitaxial wafer for a light emitting diode that has high luminance and has little luminance variation.

[0008]

According to the present invention, there is provided an epitaxial wafer for a light emitting semiconductor device, comprising at least an n-type semiconductor epitaxial layer and a p-type semiconductor epitaxial layer formed on an n-type GaP single crystal substrate. In the epitaxial wafer, the boron (B) concentration in the n-type GaP single crystal substrate is 1 × 10 ¹⁷ cm ⁻³ or less,
More preferably, by setting it to 5 × 10 ¹⁶ cm ⁻³ or less, high luminance and reduction in luminance variation are achieved.

Further, the present invention provides that the n-type semiconductor epitaxial layer and the p-type semiconductor epitaxial layer
It can be suitably used for an epitaxial wafer for a light emitting semiconductor device made of aP. Further, the present invention relates to the aforementioned n
The p-type semiconductor epitaxial layer and the p-type semiconductor epitaxial layer can be suitably used for a light-emitting semiconductor device epitaxial wafer made of GaAs _x P _1-x (0 <x <1). Further, in the invention, it is preferable that the n-type semiconductor epitaxial layer and the p-type semiconductor epitaxial layer include (Al _x Ga _{1 -x} ) _y In _{1 -y} P (0 <x <1, 0
<Y <1) can be suitably used for the epitaxial wafer for a light emitting semiconductor device composed of <y <1).

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION The present inventor first studied high luminance and reduced luminance variation of an epitaxial wafer for a GaP red light emitting diode. On an n-type GaP single crystal substrate with the same dopant and the same carrier concentration,
Even if an n-type GaP epitaxial layer and a p-type GaP epitaxial layer are formed in the same process to produce an epitaxial wafer, the brightness of the obtained light emitting diode varies greatly depending on the epitaxial wafer. Examination of the cause of the luminance variation revealed that the luminance level often differs depending on the production lot of the n-type GaP single crystal.

The relationship between various physical properties and luminance of an n-type GaP single crystal substrate was examined in detail.
It was found that there was a correlation between the boron (B) concentration in the P single crystal substrate and the luminance. That is, an n-type GaP epitaxial layer and a p-type GaP epitaxial layer are formed on an n-type GaP single crystal substrate having the same carrier concentration and different B concentrations by the same process to produce an epitaxial wafer, and the luminance and n-type GaP Investigation of the relationship between the B concentration in the single crystal substrate revealed that the epitaxial wafer had a B concentration of 1 × 10 ¹⁷ cm ⁻³ or less, more preferably 5 × 10 ¹⁶ cm ⁻³ or less, and high luminance and little luminance variation. was gotten.

Therefore, using an n-type GaP single crystal substrate as a substrate, GaP yellow-green, GaP pure green, GaAsP
The relationship between the B concentration in the n-type GaP single crystal substrate and the luminance was similarly investigated for the Al-based and AlGaInP-based epitaxial wafers for light-emitting diodes. As a result, in any of the above-described epitaxial wafers for a light emitting diode, the B concentration in the n-type GaP single crystal substrate is 1 × 10 ¹⁷ cm ⁻³ or less, more preferably 5 × 10 ¹⁶ cm ^−3.
It has been found that by setting the value to ^-3 or less, it is possible to obtain an epitaxial wafer having a high luminance and a small luminance variation. The B concentration in the n-type GaP single crystal substrate was measured by secondary ion mass spectrometry (SIMS).

The n-type GaP single crystal substrate is usually obtained from an n-type GaP single crystal grown by a liquid-sealed Czochralski (LEC) method. In the LEC method, B ₂ O ₃
Since B is used, B easily mixes in the crystal, and 1
It can have a concentration of 0 ¹⁷ cm ^-3 or more. Therefore, it is necessary to appropriately select the conditions for growing the single crystal and to reduce the amount of B mixed in the crystal. As a method for reducing B, for example, B ₂ O
By adjusting the water content contained in the ₃ there is a method of inhibiting the decomposition of B ₂ O _3. In addition, trace amounts of P ₂ O ₅ and Ga ₂ O
_By adding an oxide such as ₃ into B ₂ O ₃ ,
Can be reduced. In addition, B can be reduced by adjusting the holding time and the pulling speed before starting the single crystal pulling, for example. There may be several other ways to reduce B. Considering the effect on other properties of the single crystal, select from these methods,
Alternatively, by applying them in combination, the concentration of B in the crystal can be reduced to 1 × 10 ¹⁷ cm ⁻³ or less, more preferably 5 × 1 ¹⁷
It can be controlled to 0 ¹⁶ cm ^-3 or less.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail based on embodiments.

Embodiment 1 First, an example of a GaP red light emitting diode will be described. FIG. 1 schematically shows the structure of the GaP red light emitting diode manufactured in this example. In FIG. 1, 1 is an n-type GaP single crystal substrate, 2 is n
The type GaP epitaxial layer 3 is a p-type GaP epitaxial layer doped with Zn and O.

As the n-type GaP single crystal substrate 1, a Te-doped GaP single crystal substrate manufactured by a liquid-sealed Czochralski (LEC) method is used, and the carrier concentration is 2 × 10
¹⁷ cm ^-3 , and the main surface was (111) B surface. The n-type GaP single crystal substrate 1 is set in a substrate holder of a known horizontal slide boat, and G serving as a growth solution is set in a solution reservoir.
a metal and GaP polycrystal, and Si as a dopant
Was set in a predetermined amount. With the substrate and the solution for growth separated, this slide boat was set in an epitaxial growth furnace, heated to 1000 ° C. under a hydrogen stream, held for 1 hour, and dissolved in Ga metal until GaP polycrystal was saturated. Was. Thereafter, the substrate holder was slid to bring the substrate 1 into contact with the growth solution, and then gradually cooled to 800 ° C. to grow the Si-doped n-type GaP epitaxial layer 2 on the substrate 1. After the growth, the substrate holder is slid to separate the growth solution from the substrate 1 on which the n-type GaP epitaxial layer 2 has been grown, and then cooled to room temperature.
The substrate 1 on which the aP epitaxial layer 2 was grown was taken out.

Next, the substrate 1 on which the n-type GaP epitaxial layer 2 has been grown is set in the substrate holder of the slide boat, and Ga metal, GaP polycrystal, Zn, and Ga as a growth solution are placed in the solution reservoir. _A predetermined amount of ₂ O ₃ was set. The slide boat was set in an epitaxial growth furnace, heated to 1000 ° C. under a hydrogen stream, and maintained for 1 hour to dissolve GaP polycrystal in Ga metal until saturation. Then, slide the substrate holder to n
The growth solution is brought into contact with the substrate 1 on which the n-type GaP epitaxial layer 2 has been grown, and the temperature is increased to 1005 ° C. to partially dissolve the surface of the n-type GaP epitaxial layer 2.
After slowly cooling to 950 ° C., a p-type GaP epitaxial layer 3 doped with Zn and O was grown on the n-type GaP epitaxial layer 2. After the growth is completed, the substrate holder is slid to separate the growth solution from the substrate 1 on which the n-type GaP epitaxial layer 2 and the p-type GaP epitaxial layer 3 have been grown, and cooled to room temperature. I got

In the first embodiment, the B concentration in the crystal is reduced to 1 × 10 ¹⁷ c by reducing the amount of water in B ₂ O ₃ used for growing the GaP single crystal to lower the B concentration in the crystal.
Three levels of n-type GaP single crystal substrates having different B concentrations at m ⁻³ or less were produced. Using the n-type GaP single crystal substrate, an epitaxial wafer for a GaP red light emitting diode was manufactured by the above process. FIG. 2 shows the relationship between the B concentration in the n-type GaP single crystal substrate and the luminance of the light emitting diode in the obtained epitaxial wafer for GaP red light emitting diode.

Comparative Example 1 For comparison, a single crystal was grown by a conventional method, and the concentration of B in the crystal was 1 × 10 ¹⁷ cm ^−3.
As described above, three levels of n-type GaP single crystal substrates having different B concentrations were prepared. Using the n-type GaP single crystal substrate, an epitaxial wafer for a GaP red light emitting diode was manufactured by the above process. FIG. 2 shows the relationship between the B concentration in the n-type GaP single crystal substrate and the luminance of the light-emitting diode of the obtained epitaxial wafer for GaP red light-emitting diode together with the result of Example 1.

FIG. 2 shows that the B concentration in the n-type GaP single crystal substrate is 1 × 10 ¹⁷ cm ^-3 or less, more preferably 5 × 10 ¹⁶ cm ^-3.
It is clear that light emitting diodes obtained at cm ^-3 or less have high brightness. In addition, the variation in luminance is n-type Ga
Ga having a B concentration of 1 × 10 ¹⁷ cm ⁻³ or less in a P single crystal substrate
In the epitaxial wafer for P red light emitting diode,
σ _n-1 was 0.16. On the other hand, in the conventional epitaxial wafer for a GaP red light emitting diode having a B concentration of 1 × 10 ¹⁷ cm ⁻³ or more in the conventional n-type GaP single crystal substrate, σ _n−1 was 0.43. That is, n-type GaP
By setting the B concentration in the single crystal substrate to 1 × 10 ¹⁷ cm ⁻³ or less, the variation in the brightness of the epitaxial wafer for the GaP red light emitting diode could be reduced.

(Embodiment 2) Next, an example of a GaP yellow-green light emitting diode will be described. FIG. 3 schematically illustrates the structure of the GaP yellow-green light emitting diode manufactured in this example. In FIG. 3, 4 is an n-type GaP single crystal substrate, 5 is an n-type GaP buffer layer, 6 is a Si-doped n-type GaP epitaxial layer, and 7 is an n-type GaP doped with nitrogen (N).
The epitaxial layer 8 is a p-type GaP epitaxial layer.

As the n-type GaP single crystal substrate 4, a Te-doped GaP single crystal substrate manufactured by a liquid sealing Czochralski (LEC) method is used, and the carrier concentration is 2 × 10
¹⁷ cm ^-3 , and the main surface was (111) B surface. First, an n-type GaP buffer layer 5 was grown on the single crystal substrate 4 by a normal liquid phase epitaxial growth method. This n-type G
The aP buffer layer is doped with Si, and the carrier concentration is 4 ×
10 ¹⁷ cm ⁻³ , and the layer thickness was 100 μm.

The n-type GaP single crystal substrate 4 on which the n-type GaP buffer layer 5 has been grown is set in a substrate holder of a known horizontal slide boat, and a predetermined amount of Ga metal serving as a growth solution is set in a solution reservoir. I set it. With the substrate and Ga metal separated, this slide boat was set in an epitaxial growth furnace, the temperature was raised to 1000 ° C. under a hydrogen stream, and the substrate holder was slid into n-type GaP.
The surface of the buffer layer 5 was brought into contact with the Ga metal, held for 1 hour, and dissolved in the Ga metal until a part of the n-type GaP buffer layer 5 was saturated. At this time, Si contained as a dopant in a part of the dissolved n-type GaP buffer layer 5;
Si generated by the reduction of the quartz in the reaction tube of the epitaxial growth furnace with hydrogen dissolves into the Ga metal. Thereafter, the temperature was gradually decreased to 960 ° C., and a Si-doped n-type GaP epitaxial layer 6 was grown on the n-type GaP buffer layer 5. Next, while maintaining the temperature at 960 ° C., the atmospheric gas is switched from hydrogen to argon gas to which a predetermined amount of ammonia gas has been added. In this case, the ammonia gas reacts with the Ga solution to cause nitrogen (N) in the Ga solution.
Is taken in. Thereafter, the temperature is gradually cooled to 900 ° C.
On the doped n-type GaP epitaxial layer 6, N-doped n
A GaP epitaxial layer 7 was grown. Continued
The temperature is maintained at 900 ° C., and zinc (Zn) is contained in the atmosphere gas.
To supply a predetermined amount of Zn into the Ga solution. The temperature is gradually cooled again to 800 ° C., and the N-doped n-type G
A Zn-doped p-type GaP epitaxial layer 8 was grown on the aP epitaxial layer 7. After the growth was completed, the growth solution was separated by sliding the substrate holder and cooled to room temperature to obtain an epitaxial wafer for a GaP yellow-green light emitting diode.

In the second embodiment, the B concentration in the crystal is reduced to 1 × 10 ¹⁷ c by reducing the amount of water in the B ₂ O ₃ used for growing the GaP single crystal to lower the B concentration in the crystal.
Three levels of n-type GaP single crystal substrates having different B concentrations at m ⁻³ or less were produced. Using the n-type GaP single crystal substrate, an epitaxial wafer for a GaP yellow-green light emitting diode was manufactured by the above process. FIG. 4 shows the relationship between the B concentration in the n-type GaP single crystal substrate and the luminance of the light emitting diode of the obtained epitaxial wafer for GaP yellow-green light emitting diode.
Shown in

Comparative Example 2 For comparison, a single crystal was grown by a conventional method, and the concentration of B in the crystal was 1 × 10 ¹⁷ cm ^−3.
As described above, three levels of n-type GaP single crystal substrates having different B concentrations were prepared. Using the n-type GaP single crystal substrate, an epitaxial wafer for a GaP yellow-green light emitting diode was manufactured by the above process. Example 2 shows the relationship between the B concentration in the n-type GaP single crystal substrate and the luminance of the light emitting diode in the obtained epitaxial wafer for a GaP yellow-green light emitting diode.
The results are shown in FIG.

FIG. 4 shows that the B concentration in the n-type GaP single crystal substrate is 1 × 10 ¹⁷ cm ⁻³ or less, more preferably 5 × 10 ¹⁶ cm ^−3.
It is clear that light emitting diodes obtained at cm ^-3 or less have high brightness. In addition, the variation in luminance is n-type Ga
Ga having a B concentration of 1 × 10 ¹⁷ cm ⁻³ or less in a P single crystal substrate
In the epitaxial wafer for P yellow-green light emitting diode, σ _n-1 was 2.27. On the other hand, in the conventional epitaxial wafer for a GaP yellow-green light emitting diode having a B concentration of 1 × 10 ¹⁷ cm ⁻³ or more in the conventional n-type GaP single crystal substrate, σ _n-1 was 6.54. That is, by setting the B concentration in the n-type GaP single crystal substrate to 1 × 10 ¹⁷ cm ⁻³ or less, the variation in luminance of the epitaxial wafer for a GaP yellow-green light emitting diode could be reduced.

(Embodiment 3) Next, an example of a GaP pure green light emitting diode will be described. FIG. 5 schematically shows the structure of the GaP pure green light emitting diode manufactured in this example. In FIG. 5, 9 is an n-type GaP single crystal substrate, 10
Denotes an n-type GaP buffer layer, 11 denotes a sulfur (S) -doped n-type GaP epitaxial layer, and 12 denotes a p-type GaP epitaxial layer.

As the n-type GaP single crystal substrate 9, a Te-doped GaP single crystal substrate manufactured by a liquid-sealed Czochralski (LEC) method is used, and the carrier concentration is 2 × 10
¹⁷ cm ^-3 , and the main surface was (111) B surface. First, an n-type GaP buffer layer 10 was grown on the single crystal substrate 9 by a normal liquid phase epitaxial growth method. The n-type GaP buffer layer is doped with Si and has a carrier concentration of 4
× 10 ¹⁷ cm ⁻³ , and the layer thickness was 60 μm.

The n-type GaP buffer layer 10 is grown in a substrate holder of a known horizontal slide boat.
Type GaP single crystal substrate 9 is set, and S
Ga metal as a solution for growing the doped n-type GaP epitaxial layer 11, polycrystalline GaP, and Ga as an S source
The ₂ S ₃ by a predetermined amount set. The second solution reservoir contains p-type Ga
A Ga metal and a GaP polycrystal serving as a growth solution for the P epitaxial layer 12 were set. With the substrate and the solution for growth separated, this slide boat was set in an epitaxial growth furnace, heated to 1000 ° C. under a hydrogen stream, held for 1 hour, and dissolved in Ga metal until GaP polycrystal was saturated. Was. Thereafter, the surface of the n-type GaP buffer layer 10 is brought into contact with the growth solution in the first solution reservoir by sliding the substrate holder, and then gradually cooled to 900 ° C., and the S-doped n-type is placed on the n-type GaP buffer layer 10. A GaP epitaxial layer 11 was grown. Next, the substrate holder is further slid at 900 ° C., and the surface of the S-doped n-type GaP epitaxial layer 11 is brought into contact with the growth solution in the second solution reservoir. After a predetermined amount of Zn was introduced, the temperature was gradually cooled to 800 ° C. to grow an n-type GaP epitaxial layer 12 on the S-doped n-type GaP epitaxial layer 11. After the growth, the growth solution was separated by sliding the substrate holder and cooled to room temperature to obtain an epitaxial wafer for GaP pure green light emitting diode.

In the third embodiment, the B concentration in the crystal is reduced to 1 × 10 ¹⁷ c by reducing the amount of water in the B ₂ O ₃ used for growing the GaP single crystal to lower the B concentration in the crystal.
Three levels of n-type GaP single crystal substrates having different B concentrations at m ⁻³ or less were produced. Using the n-type GaP single crystal substrate, an epitaxial wafer for a GaP pure green light emitting diode was manufactured by the above process. FIG. 6 shows the relationship between the B concentration in the n-type GaP single crystal substrate and the luminance of the light emitting diode of the obtained epitaxial wafer for GaP pure green light emitting diode.
Shown in

Comparative Example 3 For comparison, a single crystal was grown by a conventional method, and the concentration of B in the crystal was 1 × 10 ¹⁷ cm ^−3.
As described above, three levels of n-type GaP single crystal substrates having different B concentrations were prepared. Using the n-type GaP single crystal substrate, an epitaxial wafer for a GaP pure green light emitting diode was manufactured by the above process. Example 3 shows the relationship between the B concentration in the n-type GaP single crystal substrate and the luminance of the light emitting diode of the obtained epitaxial wafer for GaP pure green light emitting diode.
The results are shown in FIG.

FIG. 6 shows that the B concentration in the n-type GaP single crystal substrate is 1 × 10 ¹⁷ cm ⁻³ or less, more preferably 5 × 10 ¹⁶ cm ^−3.
It is clear that light emitting diodes obtained at cm ^-3 or less have high brightness. In addition, the variation in luminance is n-type Ga
Ga having a B concentration of 1 × 10 ¹⁷ cm ⁻³ or less in a P single crystal substrate
In the epitaxial wafer for P pure green light emitting diode, σ _n-1 was 0.34. On the other hand, in the conventional epitaxial wafer for a GaP pure green light emitting diode having a B concentration of 1 × 10 ¹⁷ cm ⁻³ or more in the conventional n-type GaP single crystal substrate, σ _n−1 was 1.01. That is, by setting the B concentration in the n-type GaP single crystal substrate to 1 × 10 ¹⁷ cm ⁻³ or less, the variation in the luminance of the epitaxial wafer for GaP pure green light emitting diode could be reduced.

(Embodiment 4) Next, an example of a GaAsP light emitting diode will be described. FIG. 7 schematically shows the structure of the GaAsP light emitting diode manufactured in this example. In FIG. 7, reference numeral 13 denotes an n-type GaP single crystal substrate;
Is an n-type GaAs _x P _{1 -x} composition gradient layer, and 15 is an n-type GaAs
The s _x P _1-x constant composition layer 16 is a Zn diffusion p-type layer.

As the n-type GaP single crystal substrate, a Te-doped GaP single crystal substrate manufactured by a liquid sealing Czochralski (LEC) method is used, and the carrier concentration is 2 × 10 ^17.
cm ^-3 , and the main surface was a surface off by 5 ° from the (100) surface in the <110> direction. The n-type GaP single crystal substrate 13 and a G
The quartz container containing the metal a was set, and the substrate 13 and the quartz container containing the Ga metal were heated to a predetermined temperature under a hydrogen stream. Next, HCl gas is added to Ga
While flowing so as to be in contact with the metal surface, PH ₃ diluted with hydrogen, AsH ₃ and H ₂ S diluted with hydrogen were introduced into the reactor, and n-type GaAs _x P _{1 -x} was placed on the substrate 13.
A composition gradient layer 14 was grown. At this time, As composition x
Is from x = 0 at the start of growth to x = 0.35 at the end of growth
P diluted with hydrogen such that x varies continuously until
The ratio of AsH ₃ diluted with H ₃ and hydrogen was adjusted. Next, P diluted with hydrogen so as to be constant at x = 0.35
The ratio of AsH ₃ diluted with H ₃ and hydrogen is fixed, and n-type G
The n-type GaAs _x P is formed on the aAs _x P _1-x composition gradient layer 14.
_{A 1-x} constant composition layer 15 was grown. At this time, a predetermined amount of NH ₃ gas is simultaneously introduced into the reactor, and n-type GaAs _x
The P _{1 -x} constant composition layer 15 was doped with nitrogen (N).

After completion of the growth, the substrate 13 on which the n-type GaAs _x P _{1 -x} composition gradient layer 14 and the n-type GaAs _x P _{1 -x} constant composition layer 15 have been grown is taken out of the reaction furnace, and the n-type GaAs _x P _{1 -x} Zn was diffused on the surface of the GaAs _x P _{1 -x} constant composition layer 15 to form a p-type layer 16 to obtain an epitaxial wafer for a GaAsP orange light emitting diode.

In the fourth embodiment, the B concentration in the crystal is reduced to 1 × 10 ¹⁷ c by reducing the amount of water in the B ₂ O ₃ used for growing the GaP single crystal to lower the B concentration in the crystal.
Three levels of n-type GaP single crystal substrates having different B concentrations at m ⁻³ or less were produced. Using the n-type GaP single crystal substrate, an epitaxial wafer for a GaAsP orange light emitting diode was manufactured by the above process. N-type GaP of the obtained epitaxial wafer for GaAsP orange light emitting diode
FIG. 8 shows the relationship between the B concentration in the single crystal substrate and the luminance of the light emitting diode.

(Comparative Example 4) For comparison, a single crystal was grown by a conventional method, and the B concentration in the crystal was 1 × 10 ¹⁷ cm ^−3.
As described above, three levels of n-type GaP single crystal substrates having different B concentrations were prepared. Using the n-type GaP single crystal substrate, an epitaxial wafer for a GaAsP orange light emitting diode was manufactured by the above process. FIG. 8 shows the relationship between the B concentration in the n-type GaP single crystal substrate and the luminance of the light emitting diode of the obtained epitaxial wafer for GaAsP orange light emitting diode, together with the result of Example 4.

FIG. 8 shows that the B concentration in the n-type GaP single crystal substrate is 1 × 10 ¹⁷ cm ⁻³ or less, more preferably 5 × 10 ¹⁶ cm ^−3.
It is clear that light emitting diodes obtained at cm ^-3 or less have high brightness. In addition, the variation in luminance is n-type Ga
Ga having a B concentration of 1 × 10 ¹⁷ cm ⁻³ or less in a P single crystal substrate
In the epitaxial wafer for AsP orange light emitting diode, σ _n-1 was 0.94. On the other hand, in the conventional epitaxial wafer for a GaAsP orange light emitting diode having a B concentration of 1 × 10 ¹⁷ cm ⁻³ or more in the conventional n-type GaP single crystal substrate, σ _n−1 was 2.97. That is, n
By setting the B concentration in the type GaP single crystal substrate to 1 × 10 ¹⁷ cm ⁻³ or less, the variation in the brightness of the epitaxial wafer for GaAsP orange light emitting diode could be reduced.

(Embodiment 5) An example of the case of an AlGaInP light emitting diode will be described. FIG. 9 schematically shows the structure of the AlGaInP light-emitting diode manufactured in this example. In FIG. 9, reference numeral 17 denotes an n-type GaP single crystal substrate;
Is an n-type Ga _y In _1-y P composition gradient layer, and 19 is an n-type (Al
_x Ga _{1 -x} ) _y In _{1 -y} P cladding layer, 20 is an undoped (Al _x Ga _{1 -x} ) _y In _{1 -y} P active layer, 21 is p-type (Al _x Ga _{1 -x} ) _y In _{1 -y} P cladding layer, 22 is p
GaAs contact layer.

As the n-type GaP single crystal substrate, a Te-doped GaP single crystal substrate manufactured by a liquid sealing Czochralski (LEC) method was used, and the carrier concentration was 2 × 10 ^17.
cm ^-3 , and the main surface was a surface off by 5 ° from the (100) surface in the <110> direction. The n-type GaP single crystal substrate 17 was set on a susceptor of an MOCVD reactor, and after the inside of the furnace was set to a hydrogen atmosphere, the substrate was heated to a predetermined temperature. Hydrogen is used as a carrier gas, and trimethyl indium (TMI), trimethyl gallium (TMG),
By supplying phosphine (PH ₃ ) and hydrogen selenide (H ₂ Se), n-type Ga _y In is formed on the n-type GaP single crystal substrate 17.
_{A 1-y} P composition gradient layer 18 was grown. At this time, the supply amount of the source gas was adjusted so that the Ga composition y continuously changed from y = 1 at the start of growth to y = 0.5 at the end of growth. Next, trimethyl aluminum (TMA), TMI, TMG, PH ₃ ,
H ₂ Se is supplied, and the n-type (Al
_0.7 Ga _0.3) was grown _{0. 5} In _0.5 P cladding layer 19. Then, TMA, TMI, TM
G and PH ₃ were supplied, and an undoped (Al _0.2 Ga _0.8 ) _0.5 In _0.5 P active layer 20 was grown on the n-type cladding layer 19. Further, TMA, TMI, T
MG, PH ₃ and dimethylzinc (DMZ) are supplied, and p-type (Al _0.7 Ga _0.3 ) _0.5
An In _0.5 P cladding layer 21 was grown. Finally, TMG, arsine (AsH ₃ ), and DMZ were supplied as source gases, and a p-type GaAs contact layer 22 was grown on the p-type cladding layer 21 to obtain an AlGaInP orange light emitting diode epitaxial wafer.

In the fifth embodiment, the B concentration in the crystal is reduced to 1 × 10 ¹⁷ c by reducing the amount of water in the B ₂ O ₃ used for growing the GaP single crystal to lower the B concentration in the crystal.
Three levels of n-type GaP single crystal substrates having different B concentrations at m ⁻³ or less were produced. Using the n-type GaP single crystal substrate, an epitaxial wafer for an AlGaInP orange light emitting diode was manufactured by the above process. AlGaIn obtained
N of epitaxial wafer for P orange light emitting diode
FIG. 10 shows the relationship between the B concentration in the type GaP single crystal substrate and the luminance of the light emitting diode.

Comparative Example 5 For comparison, a single crystal was grown by a conventional method. The B concentration in the crystal was 1 × 10 ¹⁷ cm ^−3.
As described above, three levels of n-type GaP single crystal substrates having different B concentrations were prepared. Using the n-type GaP single crystal substrate, an epitaxial wafer for an AlGaInP orange light emitting diode was manufactured by the above process. N-type G of the obtained epitaxial wafer for AlGaInP orange light emitting diode
The relationship between the B concentration in the aP single crystal substrate and the luminance of the light emitting diode is shown in FIG.

FIG. 10 shows that B in the n-type GaP single crystal substrate
The concentration is 1 × 10 ¹⁷ cm ⁻³ or less, more preferably 5 × 10 ¹⁷ cm ⁻³
It is clear that the light emitting diode has a high brightness below ¹⁶ cm ^-3 . In addition, the variation in the brightness is caused by the fact that the B concentration in the n-type GaP single crystal substrate is less than 1 × 10 ¹⁷ cm ⁻³ of AlGaI
In the epitaxial wafer for nP orange light emitting diode, σ _n-1 was 7.45. On the other hand, in the conventional epitaxial wafer for an AlGaInP orange light emitting diode having a B concentration of 1 × 10 ¹⁷ cm ⁻³ or more in the conventional n-type GaP single crystal substrate, σ _n−1 was 20.9. That is, the B concentration in the n-type GaP single crystal substrate is set to 1 × 10 ¹⁷ cm
By setting the value to ^-3 or less, the variation in luminance of the epitaxial wafer for an AlGaInP orange light emitting diode could be reduced.

[0044]

As described above, according to the present invention,
An epitaxial wafer for a light-emitting semiconductor device having higher luminance than before can be obtained. Further, in the conventional case, a large luminance variation occurs between wafers. However, by limiting the B concentration as in the present invention, the effect of reducing the luminance variation between wafers can be obtained. In the GaAsP-based light emitting diode epitaxial wafer and the AlGaInP-based light emitting diode epitaxial wafer, the same effect can be obtained even when the emission wavelength is changed by changing the mixed crystal composition. Further, in the embodiment, n-type Ga
Although an example in which Te is used as the dopant for the P single crystal substrate has been described, similar effects can be obtained when other dopants such as Si and S are used.

[Brief description of the drawings]

FIG. 1 is a schematic diagram showing a structure of a GaP red light emitting diode according to a first embodiment.

FIG. 2 is a diagram showing the relationship between the B concentration in an n-type GaP single crystal substrate and the luminance of the GaP red light-emitting diodes according to Example 1 and Comparative Example 1.

FIG. 3 is a schematic diagram showing a structure of a GaP yellow-green light emitting diode according to a second embodiment.

FIG. 4 is a diagram showing the relationship between the B concentration in an n-type GaP single crystal substrate and the luminance of the GaP yellow-green light emitting diodes according to Example 2 and Comparative Example 2.

FIG. 5 is a schematic diagram showing the structure of a GaP pure green light emitting diode according to a third embodiment.

FIG. 6 is a diagram showing the relationship between the B concentration in an n-type GaP single crystal substrate and the luminance of the GaP pure green light emitting diodes according to Example 3 and Comparative Example 3.

FIG. 7 is a schematic view showing the structure of a GaAsP orange light emitting diode according to a fourth embodiment.

FIG. 8 is a diagram showing the relationship between the B concentration in an n-type GaP single crystal substrate and the luminance of the GaAsP orange light emitting diodes according to Example 4 and Comparative Example 4.

FIG. 9 is a schematic diagram showing a structure of an AlGaInP orange light emitting diode according to a fifth embodiment.

FIG. 10 shows AlGaI according to Example 5 and Comparative Example 5.
FIG. 4 is a graph showing a relationship between a B concentration in an n-type GaP single crystal substrate and luminance of an nP orange light emitting diode.

[Explanation of symbols]

Reference Signs List 1 n-type GaP single crystal substrate 2 n-type GaP epitaxial layer 3 p-type GaP epitaxial layer doped with Zn and O 4 n-type GaP single crystal substrate 5 n-type GaP buffer layer 6 n-type GaP epitaxial layer 7 n-doped n -Type GaP epitaxial layer 8 p-type GaP epitaxial layer 9 n-type GaP single crystal substrate 10 n-type GaP buffer layer 11 n-type GaP epitaxial layer 12 p-type GaP epitaxial layer 13 n-type GaP single crystal substrate 14 n-type GaAs _x P _{1- x} composition gradient layer 15 n-type GaAs _x P _{1 -x} constant composition layer 16 Zn diffusion p-type layer 17 n-type GaP single crystal substrate 18 n-type Ga _y In _1-y P composition gradient layer 19 n-type (Al _x Ga _{1 -x} ) _y In _1-y P cladding layer 20 undoped (Al _x Ga _{1 -x} ) _y In _{1 -y} P active layer 21 p-type (Al _x Ga _{1 -x} ) _y In _{1- y} P cladding layer 22 p-type GaAs contact layer

Claims (5)

[Claims] 1. An epitaxial wafer for a light emitting semiconductor device comprising at least an n-type semiconductor epitaxial layer and a p-type semiconductor epitaxial layer formed on an n-type GaP single crystal substrate. B) An epitaxial wafer for a light emitting semiconductor device, wherein the concentration is 1 × 10 ¹⁷ cm ⁻³ or less. 2. The B concentration in the n-type GaP single crystal substrate is 5 × 10 ¹⁶ cm ⁻³ or less.
An epitaxial wafer for a light emitting semiconductor device according to the above. 3. The epitaxial wafer for a light emitting semiconductor device according to claim 1, wherein the n-type semiconductor epitaxial layer and the p-type semiconductor epitaxial layer are made of GaP. 4. The method according to claim 1, wherein the n-type semiconductor epitaxial layer and the p-type semiconductor epitaxial layer are GaAs _x P _{1 -x}
3. The epitaxial wafer for a light-emitting semiconductor device according to claim 1, wherein (0 <x <1). 5. The semiconductor device according to claim 1, wherein the n-type semiconductor epitaxial layer and the p-type semiconductor epitaxial layer are (Al _x Ga
3. The epitaxial wafer for a light emitting semiconductor device according to claim _{1, comprising 1-x} ) _y In _1-y P (0 <x <1, 0 <y <1). 4.