The behaviour of copper dopant in p-Hg 1−x Cd x Te single crystals is analysed for in-diffusion in the samples with heterogeneous distribution of Hg vacancies and for ion beam milling. For the case of low Hg vacancy, p-Hg 1−x Cd x Te (x ∼ 0.2) material, copper is found to diffuse by a relay-race interstitial mechanism at low temperature. When the Cu-doped p-Hg 1−x Cd x Te samples are exposed to ion milling, the p-n conversion of conductivity type occurs in a substantially thick subsurface layer (∼10 µm). Unstable donor centres such as copper in interstitials rapidly relax so that residual donors control the conductivity in a converted layer after several hours. The possible causes of the incomplete p-type reconversion are discussed.

The relaxation of electrical properties of As-and Sb-doped HgCdTe epitaxial layers, which were converted into n-type by ion milling, is studied. It is shown that donor complexes formed under ion milling and responsible for p-to-n conductivity type conversion are not stable, and their concentration decreases upon storage even at room temperature. Increasing the temperature of the storage speeds up the relaxation process. It is demonstrated that the relaxation is caused by the disintegration of the donor complexes that starts right after the end of the milling process because of the decrease in the concentration of interstitial mercury atoms, which were generated during the milling. The results presented in the paper are important for the development of the technology of photodetectors based on HgCdTe doped with V-group acceptors.

The dependence of conductivity-type conversion depth in vacancy-doped Hg 1−x Cd x Te (MCT) alloys subjected to ion milling on alloy composition and treatment temperature is studied both experimentally and theoretically. It is shown that both in compositionally homogeneous crystals and in samples with a wide bandgap protective layer the dependence is defined by internal electric fields, which affect the diffusion of mercury interstitial atoms that are generated during the treatment. Results of the calculation of the effect of the potentials of a p-n junction formed by ion milling and of a varyband structure field (in samples with the protective layer) on the conversion depth fit both the original experimental data and those taken from the literature well. The data obtained confirms the validity of the diffusion model of the formation of the excessive mercury source in MCT subjected to ion milling, which was proposed by the authors previously. The results presented in the paper allow one to predict and control the conversion depth in MCT subjected to ion milling for p-n junction fabrication, which makes them useful in MCT infrared detector technology.

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