Photoeffects in CdTe with acid−grown Te layers

Abstract

Immersion of CdTe in dilute HNO₃ produces a layer of tellurium whose thickness grows with immersion time. These Te−CdTe junctions rectify and are photosensitive. Spectral response measurements show (a) a flat band extending to photon energies of 1.5 eV, characteristic of interband transitions in CdTe, (b) a peak at 1.4 eV in CdTe without a Te layer which disappears as the layer is added, and (c) a peak at 0.59 eV observed only with a Te layer present. The 1.4−eV peak is consistent with reports from electroluminescence experiments, but there are no previous reports of an effect in CdTe with energy near 0.59 eV. The latter peak may result from states created at the Te−CdTe interface.