Molecular Dynamics Study of Heteroepitaxial Growth of HgCdTe on Perfect and Dislocated (211)B CdZnTe Substrates

The presence of threading dislocations in the depletion region of Hg1–xCdxTe detectors remains a problem due to its negative impact on the electrical and electronic properties of these detectors. We used molecular dynamics (MD) simulations to study the impact of the simulated growth rate, substrate temperature, and Hg/Te flux ratio on the Hg sticking coefficient and crystallinity of Hg1–xCdxTe on a perfect (211)B CdZnTe substrate during molecular beam epitaxy (MBE) growth. The trends were consistent with the experiments, namely, a decrease in crystallinity with an increase in the growth rate, the exponential decrease of the Hg sticking coefficient with the increase in substrate temperature, and an optimum substrate temperature and Hg/Te flux ratio for a given growth rate. We then used one of the optimum growth conditions found to conduct MD simulations on (211)B CdZnTe substrates with a quadrupole of either 0° perfect, 60° perfect, 30° partial, or 90° partial dislocations. All dislocations extended into the epilayer as expected and various phenomena were observed─change of line direction, movement by climb, and the dissociation of a glide perfect dislocation into two partials. These phenomena give insight into the types of low-energy dislocations that may be present in Hg1–xCdxTe after MBE growth.