Electrical and optical studies of a tellurium‐related defect in molecular‐beam epitaxy‐grown HgCdTe

Electrical and optical studies of defects in molecular beam epitaxy (MBE)-grown HgCdTe films, undoped and doped with arsenic, were carried out. By comparing results of ion milling-assisted Hall-effect measurements with micro-Raman spectroscopy data, it was shown that the films contained electrically neutral defects related to excessive tellurium. It is suggested that these defects are Te nanocomplexes and that they are typical of the MBE HgCdTe technology. Under ion milling, they get electrically activated by interstitial mercury and form donor centers with concentration of ∼1017 cm-3, which allows for detecting them with measurements of electrical parameters of the material. Also, it can be suggested that in films doped with arsenic with high-temperature cracking, As2 dimers in the arsenic flux react with excessive tellurium and form As2Te3 donor complexes, thus preventing formation of Te nanocomplexes. Arsenic activation annealing may break As2Te3 complexes and release Te, which can again form the complexes under ion milling. (© 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)