Minority carrier lifetime in iodine-doped molecular beam epitaxy-grown HgCdTe

Abstract

The minority carrier lifetime in molecular beam epitaxy grown layers of iodine-doped Hg1-xCdxTe (x ∼ 0.3) on CdZnTe substrates has been studied. The samples demonstrated extrinsic donor behavior for carrier concentrations in the range from 2 × 1016 cm-3 to 6 × 1017 cm-3 without any post-growth annealing. At a temperature of 77 K, the electron mobility was found to vary from 104 cm2/V s to 7 × 103 cm2/V s and minority carrier lifetime from 1.6 μs to 790 ns, respectively, as the carrier concentration was increased from 2 × 1016 cm-3 to 6 × 1017 cm-3. The diffusion of iodine is much lower than that of indium and hence a better alternative in heterostructures such as nBn devices. The influence of carrier concentration and temperature on the minority carrier lifetime was studied in order to characterize the carrier recombination mechanisms. Measured lifetimes were also analyzed and compared with the theoretical models of the various recombination processes occurring in these materials, indicating that Auger-1 recombination was predominant at higher doping levels. An increase in deep-level generation-recombination centers was observed with increasing doping level, which suggests that the increase in deep-level trap density is associated with the incorporation of higher concentrations of iodine into the HgCdTe.