Method of fabrication of highly resistive GaN bulk crystals

Details Method of fabrication of highly resistive GaN bulk crystals Method of fabrication of highly resistive GaN bulk crystals

1999-12-06

2001-08-14

Utech, Benjamin L. (Department: 1765)

Single-crystal, oriented-crystal, and epitaxy growth processes;

Processes of growth from liquid or supercritical state

Havin growth from molten state

C117S907000, C117S952000

Reexamination Certificate

active

06273948

ABSTRACT:

FIELD OF THE INVENTION
This Invention relates to the method of fabrication of highly resistive GaN bulk crystals for manufacturing of optoelectronic devices.
BACKGROUND OF THE INVENTION
According to the present state of the art of growth of single crystals there are not known methods of manufacturing of highly resistive GaN bulk crystals.
OBJECT AND SUMMARY OF THE INVENTION
According to the Invention, GaN crystallization is effected in the solution of atomic nitrogen in molten mixture of the metals containing gallium in the concentration not lower than 90 at % and at least one of Periodic Table group II metals: Mg, Ca, Be, Zn, Cd in the concentration: 0.01-10 at % in order to reduce the concentration of free electron carriers in the crystal by change of microscopic growth mechanism leading to the improvement of the stoichiometry and compensation on nonintentionally introduced donor impurities. The process is conducted under nitrogen pressure 0.5-2.0 GPa and in the temperature 1300-1700° C. in order to assure the stability of GaN and high concentration of nitrogen in liquid solution. Crystallization in conducted the temperature gradient not smaller than 10° C./cm, which assures low supersaturation in the growth zone, necessary to obtain GaN crystal growth velocity lower than 0.2 mm/h, necessary for stable growth of large size crystals.
In the results of the growth process hexagonal GaN plate-like crystals are obtained, having the specific resistivity 10
4
-10
8
&OHgr;cm, characterized by high structural quality and the lattice parameters close to the perfect crystal. These so obtained crystals, are not available at present, and can be used as perfect substrates for unstrained homoepitaxial GaN layers.
The subject of the Invention is demonstrated on the examples of applications.


REFERENCES:
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patent: 9713891 (1997-04-01), None
Patent Abstracts of Japan, vol. 98, No. 5 & JP 10 007496 A (Hitachi Cable Ltd).
Porowski et al: “Thermodynamical Properties of III-V Nitrides and Crystal Growth of Gan at High N2 Pressure” Journal of Crystal Growth., vol. 178, Jun. 2, 1997, pp. 174-188,.
Karpinski et al: “Equilibrium Pressure of N2 Over Gan and High Pressure Solution Growth of Gan” Journal of Crystal Growth., vol. 66, 1984, pp. 1-10.
Yamane et al: “Preparation of Gan Single Crystals Using A NA Flux” Chemistry of Materials, vol. 9, Feb. 1997, pp. 413-416.

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