Suppression of doping striations in zone melting of InSb by enhanced convection on a centrifuge

doi:10.1016/0022-0248(82)90377-3

Journal of Crystal Growth

Volume 59, Issue 3, October 1982, Pages 548-556

https://doi.org/10.1016/0022-0248(82)90377-3 Get rights and content

Abstract

An experimental study of convective effects in horizontal zone melting of InSb at large inertial accelerations (up to 30 times earth gravity) is reported. The experiments were carried out on a centrifuge arrangement which permits to vary the driving force of convection in a wide range. The occurrence of temperature fluctuations in the melt zone and of doping striations in the growing crystal is investigated in dependence on resulting acceleration. This is explained by unsteady convection which is discussed in relation to existing theoretical work. A suppression of unsteady convection and doping striations at large acceleration is reported which has been observed for the first time in horizontal zone melting.

References (15)

D. Schwabe et al.
J. Crystal Growth
(1981)
G. Müller et al.
J. Crystal Growth
(1980)
M.J. Stewart et al.
J. Crystal Growth
(1972)
J.R. Carruthers
J. Crystal Growth
(1976)
A. Müller et al.
Z. Naturforsch.
(1964)
G.S. Cole et al.
J. Inst. Metals
(1965)
D.T.J. Hurle
Phil. Mag.
(1966)

There are more references available in the full text version of this article.

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Suppression of doping striations in zone melting of InSb by enhanced convection on a centrifuge

Abstract

J. Crystal Growth

J. Crystal Growth

J. Crystal Growth

J. Crystal Growth

Z. Naturforsch.

J. Inst. Metals

Phil. Mag.