Backside-illuminated infrared photoluminescence and photoreflectance: Probe of vertical nonuniformity of HgCdTe on GaAs

Vertical uniformity of HgCdTe epilayer is a crucial parameter for infrared detector engineering. In this work, backside illuminated infrared photoluminescence (PL) and photoreflectance (PR) measurements are carried out on an arsenic-doped Hg1-xCdxTe layer molecular-beam epitaxially grown on GaAs substrate, and the alloy composition and impurity states of the HgCdTe near the substrate are evaluated. By comparing to frontside illuminated PL and PR data, the vertical nonuniformity of composition and impurity states are evidenced. The results indicate that backside illuminated PL and PR are good pathway for evaluating contactlessly the nonuniformity of alloy composition and impurity states along the growth direction.