Temperature-dependent (11–290 K) infrared photoreflectance (PR) measurements are performed on as-grown arsenic-doped HgCdTe epilayers in a midinfrared spectral region. Main PR features near bandedge manifest clear evolution of lineshape with temperature, of which the fittings identify besides a band-band process several below-gap processes. Analyses show that these features are due to photomodulation-induced screening of donor-acceptor pairs and photomodulation of band-impurity and band-band reflectance, their intensities correlate to the joint concentration of the involved energetic states. Temperature-dependent infrared PR may be a right optical spectroscopy for identifying impurity levels in semiconductors such as HgCdTe with high-density impurities.

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