Exciton Absorption of GaSe Crystals in the Indirect Transition Region

An experiment conducted to measure the exciton absorption of semiconductor gallium selenide crystals in the indirect transition region as a function of temp. is reported. The absorption edge was measured with polarized light propagating along crystal layers to characterize the nature of optical transitions in the absorption edge region. The observed data supported the conclusion that the absorption edge is red-shifted for the polarization - > E!!- > C. Test results showing absorption curves up to 300 deg K are presented.7 refs.--G.P.K.