Flux-assisted CdTe and CdSe growth using an in-situ dynamic flux removal process

Abstract

A flux-assisted in situ dynamic-flux-removal process for growing CdTe and CdSe using a getter metal is discussed. A metal getter (e.g., stainless steel, Pt, Cu, Ni, and Ag) was placed in the annulus outside of a glassy carbon crucible containing the CdTe+Te or CdSe+Se and this was sealed within an evacuated fused quartz ampoule. The excess Te and Se were added as fluxes. After melting, the flux and some Cd(Te,Se) was removed from the crucible through volatility and reacted with the metal getter forming metal tellurides. This process was conducted at temperatures below the melting temperatures of CdTe (Tm ~1041 °C) and CdSe (Tm ~1268 °C) and once the flux was removed, the CdTe or CdSe solidified into a solid polycrystalline ingot with several large grains. Following a 24-hr soak, different cooling rates were used including 0.1 °C min-1 , 1 °C min-1 , as well as furnace, air, and water quenching. The slowest quench rate (0.1 °C min-1) yielded the largest-grained crystals for the CdTe experiments. This process was then demonstrated in a gradient furnace using Cu and Ni getters to grow CdTe samples of ~100 g. The experiments conducted for CdSe were not as successful as for CdTe, yielding products of smaller grain sizes than were achieved with CdTe.