November 26, 2018
Report

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 is discussed where crystals larger than 1-cm have been achieved over times of a few days. Here, a metal getter (i.e., stainless steel, Pt, Cu, Ni, and Ag) was placed in the annulus outside of a glassy carbon crucible containing CdTe and Te (Cd30Te70) and this was sealed within an evacuated fused quartz ampoule. During the heat-treatment, the Te flux lowered the melting temperature of the mixture. After melting, the flux (and some CdTe) 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 temperature of CdTe (~1041 °C) and once the flux was removed, the CdTe solidified into a solid polycrystalline ingot with several large grains. Following a 24-hr soak, a variety of cooling rates were evaluated including 0.1 °C min-1, 1 °C min-1, as well as furnace, air, and water quenching all with Pt as the getter. The slowest quench rate (0.1 °C min-1) yielded the largest-grained crystals. This process was then demonstrated in a gradient furnace using Cu and Ni getters to grow ingots of ~100 g. Additional data is presented showing how this approach was also used to grow CdSe (Tm = ~1268 °C), albeit with smaller grain sizes than were achieved with CdTe.

Published: November 26, 2018

Citation

Riley B.J., C.H. Henager, D.W. Matson, N.R. Overman, and D.A. Pierce. 2018. Flux-assisted CdTe and CdSe growth using an in-situ dynamic flux removal process Richland, WA: Pacific Northwest National Laboratory.