Formation and bleaching of optically-induced absorption bands in CdS:Cd,Cu crystals

Our earlier work has revealed the occurrence of three photoinduced bands in cadmium sulphide crystals appropriately doped with both cadmium and copper: one in the visible and two in the near IR region of the optical absorption spectrum. This investigation is now extended by examining the growth kinetics, their dependences on the temperature and on the excitation-light intensity, as well as the kinetics of thermal bleaching of the induced absorption. The data obtained are discussed in terms of the formation of photochemical complexes which give rise to the visible band. The IR bands are attributed to centers which are also responsible for the IR quenching of the photoconductivity.