Heat treatment and impurity effects on the photoelectron mobility in CdS monocrystals

The article provides experimental data on the way photo-electron mobility in CdS monocrystals is affected by alloying with admixtures of indium and cadmium with subsequent partial compensation of dark conductivity with copper and sulphur, and also by treatment in sulphur fumes and various thermal treatment. It was shown that alloying with impurities and thermal treatment of the types used in alloying experiments has no marked effect on photo-electron mobility, which is important for the determination of effective output (quantum) in CdS monocrystals. Since photo-electron mobility changes very little, study of photoconductivity amounts to the measurement of Ysub(f) (quantum output) and t (life of nonequilibrium current carriers). After thermal treatment the following values of photo-electron mobility were obtained for CdS: (values given for 5 series in order untreated, at 4500C, at 7500C). 1) 210+-14, 218+-16, 224+-10; 2) 216+-18, 217+-14, 233+-18; 3) 218+-10, 224+-16, 228+-16; 4) 214+-14, 218+-10, 218+-14; 5) 220+-16, 219+-15, 230+-12. On the basis of the values given for mobility in kinetic measurements, it is possible to estimate Ysub(f) and t separately for each sample, which is extremely important for the study of the kinetics of electron processes in CdS monocrystals and the control of the practically important photoelectric properties of CdS photoconductors by the creation of crystalline imperfections. (N.K.)