MASS FLUX OF ZNSE BY PHYSICAL VAPOR TRANSPORT

Mass fluxes of ZnSe by physical vapor transport (PVT) were measured in the temperature range of 1050 to 1160 degrees C using an in-situ dyna mic technique. The starting materials were either baked out or distill ed under vacuum to obtain near-congruently subliming compositions. Usi ng an optical absorption technique Zn and Se-2 were found to be the do minant vapor species. Partial pressures of Zn and Se-2 over the starti ng materials at temperatures between 960 and 1140 degrees C were obtai ned by measuring the optical densities of the vapor phase at the wavel engths of 2138, 3405, 3508, 3613, and 3792 Angstrom. The amount and co mposition of the residual gas inside the experimental ampoules were me asured after the run using a total pressure gauge. For the first time, the experimentally determined partial pressures of Zn and Se-2 and th e amount and composition of the residual gas were used in a one-dimens ional diffusion limited analysis of the mass transport rates for a PVT system. Reasonable agreement between the experimental and theoretical results was observed.