Measurement of Minority Carrier Lifetime in n-Type MBE HgCdTe and Its Dependence on Annealing

摘要

Results are presented for minority carrier lifetime in n-type molecular beam epitaxy Hg_1-xCd_xTe with x ranging from 0.2 to 0.6. It was found that the lifetime was unintentionally degraded by post-growth annealing under Hg saturated conditions in a H, atmosphere that was both time and temperature dependent. This effect was minimal or non-existent for x～0.2 material, but very strong for × 2 0.3. Hydrogen was identified as responsible for this degradation. Identical annealing in a He atmosphere avoids this degradation and results in near- theoretical lifetime values for carrier concentrations as low 1 × 10~15 cm~-3 in 20.3 material. Modeling was carried out for x～0.2 and x～0.4 material that shows the extent to which lifetime is reduced by Shockley-Real-Hall recombination for carrier concentrations below 1 × 10~15 cm~-3, as well as for layers annealed in H_2. It appears that annealing in H_2 results in a deep recombination center in Wider bandgap HgCdTe that lowers the lifetime without affecting the majority carrier concentration and mobility.