Asymptotic Analysis of Melt Growth for Antimonide-Based Compound Semiconductor Crystals in Magnetic and Electric Fields.

摘要

Single crystals of doped and alloyed antimonide-based semiconductors are needed for Air Force Applications because they serve as transparent, lattice-matched epitaxial growth templates for detectors. High-performance devices rely on good compositional homogeneity in the bulk substrate which is cut from wafers sliced from the crystal. Several important processes are being developed at AFRL in Hanscom AFB, which are the vertical gradient freezing process using submerged heater growth, the vertical Bridgman process using submerged heater growth, and the magnetic liquid- encapsulated Czochralski process. Because molten semiconductors are excellent electrical conductors, these processes apply magnetic and electric fields to control the melt motion and thus the convective transport of species during growth in order to optimize the properties of the crystal. Asymptotic and numerical modelling of these processes have provided predictions of the transport in the melt and of the compositional distribution in the crystal.