The direct transfer of excitation energy among localized states via tunneling (hopping) in semiconductors is to be investigated. This process has often been neglected in the past. A study of the extent and of the mechanisms governing this transfer related to donor-acceptor pairs (DAPs) are necessary for a full understanding of luminescence phenomena. The proper material parameters for the luminescence processes will be re-evaluated using samples which have negligible transfer or where the correction factors are known. The work will center on Zinc-Selenium, for which a large number of samples are available. The study will include a detailed examination of time decay, and of spectral and intensity evolution as a function of excitation intensity and wavelength, temperature, and impurity concentration.
