Above-Hg1-x Cdx Te-bandgap photoluminescence and interfacial channels in Hg1-x Cdx Te-CdTe heterostructure

HgCdTe-CdTe heterostructures are important for HgCdTe-based low-dimensional structures and infrared detectors. However, studies concerning parasitic heterostructure introduced by the passivation are very limited and within electrical characterizations. In this work, temperature-dependent infrared photoluminescence (PL) measurements are performed on CdTe-passivated-HgCdTe interfaces with 1064-nm laser excitation. Besides the common HgCdTe band-edge PL, abnormal PL features are observed about 100meV above the HgCdTe band gap, which are active at low temperatures and accompanied by the quench of near-band-edge ones. Photoreflectance and temperature dependent PL analysis indicate that such abnormal features are from radiative recombinations between electrons in HgCdTe and holes in the passivation layer. Such channels compete severely with the near-band-edge ones, and may deteriorate the detector performance.