Thermally induced impurity edge photoconductivity of CdS crystals

We investigate the effect of hardening on the edge photoconductivity spectra of “perfect” CdS crystals, measured at room temperature and at the boiling point of liquid nitrogen ($T$ = 77 K). It is found that hardening leads to a spectrally nonuniform increase in the photosensitivity of the semiconductor and that the effect is predominantly observed in the (impurity) edge region of the spectrum. This effect is hypothetically attributed to thermally stimulated decay of intrinsic-defect clusters.