Conductivity and Hall effect measurements were performed on dark and infra-red photo-excited p-type samples at temperatures of between 77 and 300K. Acceptor vacancy complexes with activation energies of 0.09 to 0.1eV were found to be present in the photo-excited samples. Various possible scattering mobilities were considered for both samples in order to explain the observed hole mobility. In the photo-excited sample, a scattering mobility due to vacancy complexes was suggested here for the first time to explain the results. The scattering centers were associated with native vacancy complexes which segregated at dislocation sites. The expression for the complex scattering mobility was deduced, by using the curve-fitting method, to be:

mobility = 6.6 x10-11T5exp[725/T]

M.Nagabhooshanam: Journal of the Less-Common Metals, 1990, 163[1], 63-78