Dopant diffusion in HgCdTe grown by photon assisted molecular-beam epitaxy

Abstract

The results of a systematic study of low temperature diffusion of indium and arsenic under Hg‐saturated conditions in HgCdTe epilayers grown by molecular‐beam epitaxy (MBE) are reported. Anneal temperatures ranging from 250 to 400 °C were investigated. To our knowledge, this is the first report of indium and arsenic diffusion coefficients at temperatures less than 300 °C. Indium was determined to be more stable to redistribution than arsenic in the MBE layers at the temperatures investigated. During this study, evidence of p‐type impurity outdiffusion from the substrate during anneal was discovered. Both copper and silver were observed to segregate into the HgCdTe epilayer during anneal. This latter effect represents a critical problem in the use of CdTe and CdZnTe substrates for material growth, and may be a major factor limiting yield of material and devices.