Share Email Print

Proceedings Paper

Interface demarcation in Bridgman-Stockbarger crystal growth of II-VI compounds
Author(s): Donald C. Gillies; Sandor L. Lehoczky; Frank R. Szofran; Ching-Hua Su; David J. Larson Jr.
Format Member Price Non-Member Price
PDF $17.00 $21.00

Paper Abstract

NASA has considerable interest in the growth of strategically important materials in microgravity. Bridgman-Stockbarger directional solidification within a sealed ampoule are planned for CdZnTe, HgCdTe, HgZnTe and GaAs. In order to optimize the thermal parameters for the growth conditions, it is necessary to characterize the furnace and understand its behavior. This entails the use of appropriate thermal modelling based on the known physical properties of the material, the ampoule material and the furnace itself. A suitable test is the determination of the shape and location of the solid-liquid interface relative to the furnace. Electrical and chemical etching techniques have been used to locate this interface for certain materials. One of these, germanium doped with gallium, a material with well-known properties, has been used to characterize the furnace model. Demarcation has been extended to cadmium telluride by post-growth examination of the precipitation of tellurium inclusions at positions of abrupt thermal changes in the furnace regime. Deliberately imposed mechanical vibration of the melt can also produce evidence of interface location. This work was done with infrared microscopy. Other techniques, available in termary solid solutions, involve the effect of change of lower zone furnace temperatures on the compositional profile. Examples of demarcation are shown in gallium-doped germanium, cadmium telluride, and mercury zinc telluride.

Paper Details

Date Published: 1 August 1991
PDF: 9 pages
Proc. SPIE 1484, Growth and Characterization of Materials for Infrared Detectors and Nonlinear Optical Switches, (1 August 1991);
Show Author Affiliations
Donald C. Gillies, NASA/Marshall Space Flight Ctr. (United States)
Sandor L. Lehoczky, NASA/Marshall Space Flight Ctr. (United States)
Frank R. Szofran, NASA/Marshall Space Flight Ctr. (United States)
Ching-Hua Su, NASA/Marshall Space Flight Ctr. (United States)
David J. Larson Jr., Grumman Corporate Research Ctr. (United States)

Published in SPIE Proceedings Vol. 1484:
Growth and Characterization of Materials for Infrared Detectors and Nonlinear Optical Switches
Randolph E. Longshore; Jan W. Baars, Editor(s)

© SPIE. Terms of Use
Back to Top
Sign in to read the full article
Create a free SPIE account to get access to
premium articles and original research
Forgot your username?