JPS5843898B2 - Vapor phase growth method for compound semiconductor single crystal thin films - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for vapor phase growth of an indirect transition type gallium arsenide phosphide mixed crystal epitaxial film suitable for manufacturing a long-life light emitting diode.

Indirect transition type gallium arsenide phosphide mixed crystal (GaAs, 11-z Px (0,45≦X<])
) I pitaxial films are used in the production of neutral color light emitting diodes such as red, orange, amber, and yellow.

Such an epitaxial film is usually formed on a single crystal substrate made of GaP or the like, and its cross section in the epitaxial growth direction has a structure as shown in FIG.

In FIG. 1, 1 is a single crystal substrate such as GaP.

2 is an epitaxial layer having the same composition as the single crystal substrate 1 such as GaP, 3 is a gradient end layer in which the mixed crystal ratio X gradually changes to the target value, and 4 is GaAs 1 having the target mixed crystal ratio.
The XPX epitaxial layer or 5 was doped with nitrogen as an isoelectronic trap.

It is a GaAs1xPx epitaxial layer.

Conventionally, when epitaxial films such as those described above are grown in a vapor phase, a group Ⅰ element, that is, gallium, contained in the epitaxial film growth gas has been used.

Atomic ratio of group Ⅰ elements, ie, phosphorus and arsenic.

Growth was performed by selecting (Ga)/(As+P'l within the range of 0.5 to 2).

However, the light emitting diode manufactured using the epitaxial film manufactured based on the above conventional method has
There was a problem that the service life was short, that is, the brightness deteriorated significantly.

For example, in the case of an orange light emitting diode, 1 forced deterioration condition is 350 with a mesa type p-n1j junction with a diameter of 180 μm.
A prismatic light emitting diode of μm x 350 μm x 250 μm (thickness) is attached to a TO-18 type head, and a pulse current with a repetition period of IKHz and a current density (peak value) of 240 A/crA is applied to the diode. Sign η.

The brightness value of the diode after 168 hours (1 week) (
According to the conventional method, the percentage of the ratio of the attenuated brightness value) to the brightness value before the start of application (initial brightness value) was approximately 35% to 40%.

Further, in the case of a yellow light emitting diode, when measured under the same conditions, the brightness deteriorated to 40 to 45% of the initial brightness.

As a result of intensive research, the present inventors have found that (Ga)/(A
By growing a GaAsI XPX mixed crystal epitaxial film in a vapor phase with s+P) of 2.5 or more.

The present invention was achieved by discovering that the above-mentioned problems of the conventional method can be solved.

That is, one object of the present invention is to provide a method for vapor phase growth of an indirect transition type GaAs1 XPX mixed crystal epitaxial film suitable for manufacturing a long-life light emitting diode.

The above object of the present invention is to vapor phase grow an indirect transition type GaAs1 XPX (0,45<X<1) mixed crystal epitaxial film on the surface of a single crystal substrate.

(Ga) contained in the above epitaxial film growth gas
This can be achieved by setting the atomic ratio of /(As+P) to 2.5 or more.

When a GaAs, XPX epitaxial film is grown in vapor phase by the method of the present invention, the mixed crystal ratio X is 0.45<
1, but in particular by selecting a value in the range 0.50<X<1.

The range of 660 to 570 nm has high utility value, that is,
An epitaxial film suitable for manufacturing a light emitting diode having an arbitrary peak emission wavelength of orange to yellow can be obtained.

In this case, since the obtained epitaxial film is of the indirect transition type, nitrogen is doped as an isoelectronic trap in the part of the 0 light emitting diode that becomes the light emitting recombination part, as shown in FIG. 1, in order to improve the 0 light emission efficiency. is preferred.

In growing the above epitaxial film, it is appropriate that CGa)/(As+P) in the growth gas be 2.5 or more, preferably 3 or more.

Also, only when growing layer 4 and layer 5 in Fig. 1 (G
a )/(A s +P) may be set to the above value.

The above method is more effective when the mixed crystal ratio X is small.

According to the test method described above, a light emitting diode manufactured using a wafer having an epitaxial film grown by the method of the present invention has a high initial brightness even in the red to yellow range, where long-life light emitting diodes have not been able to be obtained in the past. against so
1%, and the lifespan of a light emitting diode was significantly improved compared to the conventional method.

As explained above, the industrial utility and value of the method of the present invention is extremely limited.

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

Example 1 Sulfur (S) was added with 3.4X]O17 atoms/Crn3.

The crystallographic plane orientation is 4 in the <110> direction from the (100) plane.
The displaced GaP single crystal substrate and the high-purity Ga-containing quartz boat were each placed at predetermined locations in a horizontal quartz epitaxial reactor with an inner diameter of 60 m and a thickness of 0 cIIL.

Next, argon (Ar) gas was introduced into the reactor for 15 minutes to sufficiently replace and remove air, and then high-purity hydrogen (H2) was introduced as a carrier gas at a rate of 1800 cc/min.
The flow of water was stopped and the temperature rising process started.

The temperatures of the Ga-containing quartz boat installation area and the Ga P single crystal substrate installation area are 770°C and 870°C, respectively.
After confirming that the peak emission wavelength was kept constant, vapor phase growth of a GaAs,-)(Px epitaxial film with a peak emission wavelength of 630±]Onm was started.

Initially, 22 cc/min of hydrogen sulfide (H2S), an n-type impurity diluted with nitrogen gas to a concentration of 20 ppm, was introduced, and 55 cc/min of GaCl, an element of Group Ⅰ of the periodic table, was introduced.
In order to generate high-purity hydrogen chloride gas (HCl), 55 cc per minute is blown into the center bottom of the Ga reservoir in the quartz boat, and is blown out from the upper surface of the Ga reservoir, on the other hand, as a Group V element component of the periodic table.

Hydrogen phosphide (PH3) diluted with H2 to a concentration of 11 parts was introduced at a rate of 200 cc per minute, and the first GaP
An epitaxial layer (FIG. 1, corresponding to 2) was grown on a GaP single crystal substrate (FIG. 1, corresponding to 1).

Next, without changing the amount of H2S and HCI gas introduced, the amount of PH3 introduced was increased from 200 cc/min to 120 cc/min.
cc, and at the same time hydrogen arsenide (AsH3) diluted with H2 to a concentration of 11 parts per minute from OCC to 8 parts per minute.
X was introduced while gradually increasing the concentration to 0 cc, and it collapsed in 80 minutes, forming the second GaAst xPx epitaxial layer (Fig. 1, 3
) was grown on the Jth GaP epitaxial layer.

For the next 30 minutes, H2S, HCI, PH3゜AsH3
without changing the amount introduced, i.e. 22 c/min respectively.
A third GaAs 1-xPx epitaxial layer (corresponding to 4 in Fig. 1) was grown on the second GaAs 1 .

For the final 50 minutes, H2S, HCl, PH3°AsH3 were introduced at 180 c/min for nitrogen isoelectronic trap inlet while introducing the same amounts.
A fourth GaAs, -XPx epitaxial layer (corresponding to FIG. 1) is grown on the third GaAs,

Vapor phase growth has been completed.

In the case of this example (G a )/(A s +P)
was held at 2.5 during the entire growth period.

1. of the obtained epitaxial film. Second. The thickness of each of the 3rd and 4th epitaxial layers is 5 μm.

39/J, fTL x 1511m, 24 μm, the mixed crystal ratio X of the fourth epitaxial layer is 0.66, and
The n-type carrier concentration was 3.5 x IO16am-3.

Next, using ZnAs2 as a diffusion source, Zn, which is a p-type impurity, is
was diffused to form a pnn association at a depth of 6 μm from surface light.

The sheet resistance of this product was 15Ω/mouth.

Subsequently, electrodes were formed by photolithography and vacuum evaporation to form a 350 μm structure having a mesa-type p-n rattan with a diameter of 180 μm.
A prismatic light emitting diode of x 350 μm x 200 μm (thickness) was formed and its lifespan was measured by the test method described above. As a result, the attenuation brightness value was 85 times the initial brightness value.

In addition, the initial brightness value was 1510 Ft-L at a current density of 10 and without an epoxy coat.

Example 2 When growing layers 2 and 3 in FIG. 1, the HCI supply rate was set at 33 cc per minute, and Ga)/(As+P, 1 was changed to 1.
GaAs1-X was prepared in the same manner as in Example 1 except that the
A Px mixed crystal epitaxial film was formed.

When the life span and initial brightness of the light emitting diode were measured in the same manner as in Example 1, they were each 81%.

It was 1490Ft-L.

Example 3 The supply rate of HCI was 132 cc/min, (Ga, l/min).
6 in the same manner as in Example] except that (As+P) was set to 6.
GaAs1-X with a peak emission wavelength of 30±IONm
A Px mixed crystal epitaxial film was grown.

When the lifetime and initial brightness were measured by the same method as in Example 1, they were 90% and 1500 Ft-L, respectively.

Example 4 A GaP single-crystal substrate doped with 4.4 x IO17 atoms/cIn3 and with one plane orientation deviated by 5° from the (100) plane to the <110> direction was prepared as described in Example 1. Installed together with a Ga port in a similar epitaxial reactor, yellow light emission (peak emission wavelength 590±IONnm)
) GaAs, -xPx epitaxial layer was grown in vapor phase.

The temperature of the part where the Ga-containing quartz boat is installed is 770°C.

The temperature of the portion where the GaP single crystal substrate is installed is kept constant at 880° C., and the first GaP evixial layer (FIG. 1) is formed.

For the growth of 2), the supply rates of each gas were set as H2S: 22 cc/min, PH3: 200 cc/min, HCI: 66 cc/min, and carrier-attached 2: 1800 cc/min.

Introducing the shingle for 10 minutes, followed by a second GaA s 1-
XPx epitaxial layer (Fig. 1, 3), H2S:
22 cc/min, HCI: 66 cc/min, with carrier 2:/min] 800 cc, PH3' 200 c/min
AsH3 is gradually reduced to 175cc from c.
: Gradually increase from Occ to 25cc per minute\,8
The shingles were introduced for 0 minutes and vapor phase growth was performed.

A third GaAs1-XPx epitaxial layer (Fig. 1,
4), H2S: 22 cc per minute, HCI: 8 cc per minute
8cc, with carrier 2: 1800 cc/min, PH3
'175 cc/min, AsH3: 25 cc/min was introduced for 30 minutes for vapor phase growth, and then the fourth GaAs
1 XPX epitaxial layer (Fig. 1, 5)
: 22cc/min, HCI: 66cc/min, with carrier 2
: 1800 cc/min, PH3' 175 cc/min,
AsH3: 25 cc per minute, NI (3: 20 cc per minute
0 cc was introduced for 50 minutes to perform vapor phase growth.

In this example, (Ga)/CAs+P, l
was kept at 3.

When the life and initial brightness of the 0 light emitting diode were measured in the same manner as in Example 1, they were each 91%.

The current density was 3000 Ft-L (current density 20 A/CIIt).

[Brief explanation of drawings]

Figure 1 shows GaAs, XPx, formed on a single crystal substrate.
FIG. 2 is a vertical cross-sectional model diagram of a mixed crystal eviximal film. 1... Single crystal substrate, 2... Epitaxial layer having the same composition as 1, 3... Gradient layer, 4... GaAs1 XPX epitaxial layer, 5 ...GaAs doped with nitrogen
Px Ebitaxia-X le layer.

Claims (1)

[Claims] 1 In a method for vapor phase growing an indirect transition type gallium arsenide phosphide mixed crystal epitaxial film on a single crystal substrate, the atomic ratio of gallium to phosphorus and arsenic contained in the epitaxial film growth gas (Ga)/ (As+P) is 2.
5 or more.