The photoconduction spectrum of GaS and GaS (:Er) stratified monocrystals irradiated by gamma-quanta

Full text: The photoconductivity of both GaS and GaS(:Er) irradiated by gamma-quanta with the dose 20-1000 krad was investigated at the room temperature. A maximum at 0,510 m and extrinsic peaks at both 0,580 m and 0,650 m were observed in the PS of the initial samples of GaS. Except the maximum at 0,510 m, an extrinsic peak at 0,620 m was present at the GaS(:Er) PS. After irradiating both GaS and GaS(:Er) samples with the dose 20 krad, photoconductivity rises. Photoconductivity decreases at 100 krad, in so doing the maximum of it does not change and besides that additional extrinsic peaks are observed at both 0,700 m and 0,925 m. We note that at 0,580 m the intensity of the peak rises but it decreases at 0,650 m. The initial peaks disappear at 300 krad and an additional maximum appears at 0,620 m. The GaS PS gets narrow at 800 krad but its sensitivity decreases, and the alignment of the characteristic tail occurs. While a dose increases to 1000 krad, sensitivity and extrinsic peaks disappear. Photosensitivity reestablishes itself relatively after annealing at 3500 degrees centigrade for 30 minutes but in this case extrinsic peaks are observed at both l=0,750 m and l=0,660 m. It is found that defects in GaS caused by gamma-radiation form systems with the initial defects and diminish the concentrations of recombination centers. The further rise in irradiation leads to the decay of the systems and this is a way to increase the concentration of defects, as a result of that the photosensitivity of the samples decreases