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Epitaxial Crystal Growth

IP.com Disclosure Number: IPCOM000074130D
Original Publication Date: 1971-Mar-01
Included in the Prior Art Database: 2005-Feb-23
Document File: 3 page(s) / 42K

Publishing Venue

IBM

Related People

Chicotka, RJ: AUTHOR

Abstract

Single crystal epitaxial growth of bulk ternary semiconductor alloys has not been achieved when there is an appreciable lattice mismatch between the epitaxially deposited ternary alloy and the seed crystal. Single crystal growth may be achieved if the lattice parameters of the epitaxially grown solid and the seed crystal are about the same, e.g., within 1%. A process is described herein of forming a single crystal seed by the partial solidification of a pseudo-binary ternary alloy onto one of its terminal components including steps of the prior solid-liquid-solid method described in Abstract No. 73 by S. B. Blum and R. J. Chicotka: in Journal of the Electrochemical Society, Vol. 117, No. 3, March 1970, p.

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Epitaxial Crystal Growth

Single crystal epitaxial growth of bulk ternary semiconductor alloys has not been achieved when there is an appreciable lattice mismatch between the epitaxially deposited ternary alloy and the seed crystal. Single crystal growth may be achieved if the lattice parameters of the epitaxially grown solid and the seed crystal are about the same, e.g., within 1%. A process is described herein of forming a single crystal seed by the partial solidification of a pseudo-binary ternary alloy onto one of its terminal components including steps of the prior solid-liquid-solid method described in Abstract No. 73 by S. B. Blum and R. J. Chicotka: in Journal of the Electrochemical Society, Vol. 117, No. 3, March 1970,
p. 940; and the Electrochemical Society Extended Abstracts, Spring Meeting, The Electrochemical Society, Spring Meeting, Los Angeles, California, May 10- 15, 1970, p.202.

In the noted prior solid-liquid-solid method, a mixed crystal, e.g., Ca(x)In(1- x)P, of controlled composition in the growth direction, either of substantially homogeneous composition or of variable composition, is prepared from the melt or liquid solution. Illustratively, the starting materials are two different pure III-V compounds with different melting points, e.g., GaP and Inp, which are to be the components from which the mixed crystal is to be grown. A three layered composite or charge is fabricated consisting of a layer of the lower melting compound which is flanked on both top and bottom by layers of the higher melting compound. The composite is established in a crucible which is sealed in a quartz ampoule in vacuum to form an assembly. When an over-pressure of either an inert or a reactive gas is required, the quartz ampoule is sealed inside a stronger container, e.g., of graphite. The assembly is allowed to equilibrate isothermally in a furnace at a given temperature to yield a liquid solution from which the desired solid solution of mixed crystal can crystallize. For crystal growth with homogeneous composition, the assembly is lowered slowly into a slightly cooled temperature zone of the furnace and crystallization of the mixed crystal occurs at the lower one of the two liquid-solid interfaces. A single crystal is obtained by epitaxial growth when the substrate is a single crystal seed. As the liquid becomes depleted in the higher melting component at the growth interface, the dissolution of the higher...