Homo-epitaxial films were grown by the co-evaporation of CdTe and P in a vacuum where the P vapor was ionized and accelerated towards the substrate. Hole densities of up to 2 x 1017/cm3 were obtained by using an ion energy of 60eV. The effects of residual ion damage were studied by using cross-sectional transmission electron microscopy, etch-pit density, and minority-carrier diffusion length techniques. It was found that the ion damage depended upon both the ion dose and the ion energy. Reduction of the ion energy to below 60eV resulted in lower doping densities but, by using electron irradiation and a Cd over-pressure during deposition, it was possible to achieve similar doping levels for 20eV ions, while reducing the ion damage. At an ion energy of 20eV, and using electron irradiation of the growing film and an 0.2% over-pressure of Cd, films with a hole density of 1017/cm3 and a diffusion length of 0.35 were obtained.

D.Kim, A.L.Fahrenbruch, A.Lopez-Otero, R.H.Bube, K.M.Jones: Journal of Applied Physics, 1994, 75[5], 2673-9