Impurity activation in MBE-grown as-doped HgCdTe by modulated photoluminescence spectra

Modulated photoluminescence spectra have been performed to investigate the impurity activation in MBE-grown As-doped Hg_1-xCd_xTe (x 0.3). The results show that the doped As mainly acting as donors in the as-grown samples can be fully activated as As_Te by two-stage anneals of 285°C/16 h + 240°C/48 h, of which the ionization energy has been determined to be about 10.5 meV, slightly smaller than that of intrinsic V _Hg (about 14.5 meV). However, the higher activation temperature (e.g. 400°C) at the first-stage can produce large numbers of excessive V _Hg and seriously deteriorate the quality of epilayers. This could give a brief guideline for preparing extrinsic p-type HgCdTe materials or devices.