Low (approximately 5K) temperature photoluminescence spectroscopy was used to study undoped CdTe epilayers which had been grown, by means of molecular beam epitaxy, onto (211)B-oriented bulk GaAs at substrate temperatures which ranged from 230 to 275C. The emission spectra of all of the samples revealed signs of the diffusion of Ga and As atoms from the substrate. A broad low-amplitude emission band which was observed at 1.594eV was attributed to the GaCd donor level in CdTe. A donor-acceptor pair recombination which was observed at 1.51eV was attributed to the substitutional GaCd donor and AsTe acceptor. The level of compensation in the CdTe layers was deduced from the energy shift in the donor-acceptor emission peak with excitation power. The lowest degree of compensation was observed in a sample which had been grown at 230C. Also, a bright emission peak was observed at 1.47eV. This peak, which had previously been observed in homo-epitaxially and hetero-epitaxially grown CdTe, was attributed to the electron-hole recombination of a structural defect in the CdTe/GaAs epilayers; with an electronic binding energy of about 0.13eV.

J.S.Gold, T.H.Myers, N.C.Giles, K.A.Harris, L.M.Mohnkern, R.W.Yanka: Journal of Applied Physics, 1993, 74[11], 6866-71