Study of alloy disorder in (Hg,Cd)Te with the use of infrared photoluminescence

摘要

Infrared photoluminescence (PL) measurements were used to probe compositional disorder in semiconductor (Hg,Cd)Te alloy. PL was studied in Hg_(1-x)Cd_xTe samples with x=0.38 and 0.57,fabricated by molecular beam epitaxy on GaAs substrates. Both as-grown and annealed in Hg vapor and in He atmosphere samples were studied. In all the samples, the PL peak energy was found to be redshifted from the position of band-to-band recombination maximum expected from the energy gap of the material. The value of the shift depended on temperature. This effect was attributed to recombination of excitons localized at compositional fluctuations, and an analysis was carried out that provided a way for evaluation of a fluctuation measure. The amplitude of the fluctuations was shown to strongly decrease as a result of post-growth annealing.