THE ROLE OF ACCELERATED CRUCIBLE ROTATION IN THE GROWTH OF HG1-XCDXTE AND CDTE/CDZNTE

Bulk growth methods for producing Hg1-xCdxTe (MCT), CdTe and CdZnTe are still important for a number of applications. Infrared detectors, particularly photoconductors, are still made in bulk-grown MCT and the CdTe/CdZnTe family of materials are crucial as lattice-matched substrates in the growth of layers of MCT by several epitaxial techniques, particularly Liquid Phase Epitaxy, (LPE). For many years the Accelerated Crucible Rotation Technique, (ACRT), has been used in the Bridgman growth of MCT and more recently in the Bridgman growth of CdTe/CdZnTe and in the Travelling Heater Method, (THM), for both MCT and CdTe. This paper reviews tile various applications of ACRT to the growth of these important semiconductor materials. ACRT is shown to produce increases in stable growth rates, marked improvements in compositional uniformity, larger single crystal regions, better crystalline quality, lower second phase precipitate levels and improved control of segregation behaviour. All of these changes are compared, where possible, to tile equivalent growth technique used in tile absence of ACRT. Theroretical considerations of the fluid flows produced by ACRT can help in understanding the differences in material properties obtained. Mass and heat transfer effects have been studied but there is, as yet, no complete model which can explain the interactions between heat, mass and fluid flows and their combined effect on tile growth process.