The energy spectra of the mercury vacancy, the most common acceptor in HgCdTe material, is studied via numerical calculations and low temperature photoconductivity (PC) measurements of 'vacancy-doped' HgCdTe films with low cadmium content. Since the Hg vacancy is known to be a double acceptor, the model for the helium atom was adopted for degerate valence band of zinc blende semiconductors to classify the observed PC bands. This approach provides a fairly good description of the photoionization of both neutral and singly-ionized vacancy when the central cell potential is taken into account.

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Mercury vacancies, acting as double acceptors, are the dominant point defects in ternary HgCdTe alloys. Though HgCdTe is one of the leading materials in infrared optoelectronics, the energy spectra of the vacancies are still a matter of some debate. This work investigated the rates at which holes are captured to a singly ionized mercury vacancy via acoustic phonon emission in narrow-gap Hg1−xСdxTe with technologically relevant x~0.22. Combined with the calculated rates of intracenter transitions, the data allow one to predict the most pronounced optical transitions in the emission spectrum of a double-charged acceptor. The results are sustained by the photoluminescence spectroscopy in the terahertz domain, allowing one to identify the emission band that is related to neutral vacancies.

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