Photoluminescence spectra of polycrystalline ZnSe in different experimental geometries

. We study the photoluminescence in polycrystalline ZnSe synthesized using a chemical vapour-deposition technique, which arises from excitation by the sources of different types and wavelengths. Two experimental geometries are used, which are related to the normal incidence of exciting radiation upon either polished or unpolished ZnSe surfaces. The excitation from the polished surface is carried out by the lasers with the wavelengths λ ex = 335 and 325 nm (i.e., the photon energies higher than the bandgap, hv ex > E g ), semiconductor lasers with λ ex = 532, 642 and 785 nm (i.e., hv ex < E g ) and a xenon lamp. The sample is also excited from the unpolished surface, using the lasers with λ ex = 325 nm ( hv ex > E g ) and λ ex = 532 nm ( hv ex < E g ), as well as the semiconductor laser with λ ex = 532 nm ( hv ex < E g ). Following from our experimental results, we analyze and compare the edge (exciton) luminescence and the impurity-defect luminescence. Different behaviours of the luminescence spectra are observed, which depend on the type of excitation. Instruments) grating 1800 and ANDOR IDUS CCD (DU420-OE respectively them spectral of our