JPS5825079B2 - Vapor phase epitaxial growth method of GaP single crystal layer - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for vapor phase epitaxial growth of a GaP single crystal layer suitable for manufacturing green light emitting diodes.

related.

Conventionally, light emitting diodes that emit green light have been manufactured by doping an n-type GaP epitaxial wafer doped with nitrogen, which is an isoelectronic trap, with zinc, which is a p-type impurity, using a thermal diffusion method to form a p-n junction. was.

However, when using such a method, it is difficult to obtain a sharp change in the carrier concentration at the pn junction, and a wide depletion layer is formed at the pn junction, making it difficult to manufacture a light emitting diode with high luminous efficiency. It was difficult to do so.

Furthermore, when using a liquid phase epitaxial growth method, the process is complicated and mass productivity is lacking.

The present inventors have arrived at the present invention as a result of intensive research to solve the problems of the conventional method described above.
The object of the present invention is to provide a new method for vapor phase epitaxial growth of single crystal layers.

The above object of the present invention is to provide n-type G in contact with the single crystal substrate.
vapor phase epitaxial growth of the aP single crystal layer, followed by
A nitrogen-doped n-type GaP single-crystal layer is grown by vapor phase epitaxial growth to a thickness of at least 10 μm, and the nitrogen-doped n-type GaP single-crystal layer is further grown using dialkylzinc as a p-type impurity source, and the above-mentioned single-crystal substrate This is achieved by vapor phase epitaxial growth to a thickness of at least 10 μm while gradually lowering the temperature.

GaP is most suitable for the single crystal substrate used in the present invention, but single crystal substrates such as Ge or Si may also be used.

The crystallographic plane orientation of the surface of the single crystal substrate has a great influence on the crystallinity of the obtained single crystal layer, but the (100) plane, or more preferably the plane having an inclination of 2 to 5 degrees with respect to the (100) plane is extremely reasonable.

During epitaxial growth, the temperature of the substrate is 80°C.
During the growth of the p-type layer, the temperature is gradually increased to 50-100℃ over the entire growth period of the p-type layer.
℃ lower.

As a result, the rise of the p-type carrier concentration at the pn junction becomes steeper, the thickness of the carrier depletion layer is reduced, and the luminous efficiency can be improved.

In addition, since GaP is an indirect transition type, doping with nitrogen, which is an isoelectronic wrap, is performed to improve the luminous efficiency.
When measured from the pn junction and formed on both sides of the pn junction, that is, on the p-layer side and the n-layer side, respectively, with a width sufficiently larger than the carrier diffusion length, the injected carriers will be sufficiently radiatively recombined, resulting in improved luminous efficiency. do.

That is, it is appropriate to form nitrogen doped layers of 10 μm or more, preferably 20 to 30 μm, on both sides of the pn junction.

As the dialkylzinc used for growing the p-type layer, dimethylzinc, diethylzinc, diluted by 10 to 100 pX with hydrogen, nitrogen, argon, etc., and other alkyl groups having carbon atoms of 4 or less are suitable.

Further, NH3 is used for nitrogen doping.

The luminance of the light emitting diode manufactured using the epitaxial wafer according to the method of the present invention was 5000 Ft-L or more, which was two to three times as high as that of the conventional product.

Furthermore, since there is no need to perform thermal diffusion of p-type impurities, the process is simplified, and there is no heat-induced deterioration of the epitaxial wafer, improving productivity, making the method of the present invention extremely valuable in industrial applications. .

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

EXAMPLE In a horizontal vapor phase epitaxial reactor, metal Ga and a GaP single crystal substrate whose crystallographic plane orientation was tilted by 5° in the <110> direction with respect to the (100) plane were placed.

The temperature of the metal Ga installation part was raised to 750°C, and the temperature of the substrate installation part was raised to 820°C.

After the temperature of the reactor reaches the set value, increase the concentration of 40% with nitrogen gas.
pp! 20rnl/min of diluted H2S and 60rnl/min of HC7 for Ga transport. rnl 1 min, and 200 ml/min of PH3 diluted with hydrogen gas to a concentration of 12% was introduced.
An n-type GaP single crystal layer was grown by vapor phase epitaxial growth for 0 minutes.

Further, 35 ml of NH3 was introduced to form an n-type GaP single crystal layer doped with 1 nitrogen by vapor phase epitaxial growth for 40 minutes.

Next, stop the supply of H2S and increase the concentration by hydrogen gas.
ppm < this diluted diethylzinc ((C2H5)2z
n) was introduced at 25 m1/min, and the substrate temperature was gradually lowered from 820°C to 720°C (decrease rate 1.75°C/min).
An n-type GaP single-crystal layer doped with nitrogen was grown under the same conditions.

The thickness of each layer of the obtained GaP epitaxial layer/''% is 48 μm, 23 μm, and 2 μm, respectively, in the order of description above.
2 μm, and the carrier concentration is similarly I x 101
7/m, 7 x 1016/7 and I x 101
It was 8/m.

The brightness of a green light emitting diode (peak emission wavelength 567 nm) with a chip size of 350 μm x 350 μm manufactured from the above epitaxial wafer was 7500 Ft-L on average without epoxy coating and under the conditions of a current density of 20 A/crl.

This is the average brightness of conventional products measured under the same conditions of 250
This corresponds to three times 0Ft-L.

Claims (1)

[Claims] 1. In a method of vapor phase epitaxial growth of a GaP single crystal layer having a pn junction on a single crystal substrate, an n-type GaP single crystal layer is vapor phase epitaxially grown in contact with the single crystal substrate, and then a nitrogen-doped n Type GaP
A single crystal layer was grown by vapor phase epitaxial growth to a thickness of at least 10 μm, and a nitrogen-doped n-type Ga
A method characterized in that the P single crystal layer is grown by vapor phase epitaxial growth to a thickness of at least 10 μm while using a dialkyl subacute as a p-type impurity source and gradually lowering the temperature of the single crystal substrate.