Temperature dependence of the responsivity of II-VI ultraviolet photodiodes

High-temperature dependence, up to 150 degrees C, of the photoresponsivity of ZnS, ZnSTe, and ZnSSe photodiodes was investigated in this study. It was found that, in general, the responsivity at higher temperatures will shift to longer wavelengths because of band-gap narrowing. A remarkable observat ion is that the near-band-edge responsivities of these diodes increase at h igher temperature. We believe that this observation is attributed to the ch ange of the density-of-state distribution due to lattice expansion at high temperatures, and a simplified model is used to illustrate this hypothesis. (C) 2000 American Institute of Physics. [S0003-6951(00)04009-2].