PHOTOVOLTAIC EFFECT AND ELECTRONIC-TRANSITIONS IN RBAG4I5

A study has been made of the effect of local light irradiation and sil ver saturation on the contact photo-emf excitation spectrum of alpha-R bAg4I5 superionic crystals at room temperature. It was found that irra diation with light having energies 2.75 eV and 2.92 eV causes color ce nters formation in the crystals. The possible nature of the bands in t he photo-emf excitation spectrum is discussed. Time dependences of the photo-emf for the main excitation bands were measured at various illu mination levels. A characteristic asymmetry of the relaxation curves g overned by the excitation kinetics was observed at high illumination i ntensities. The estimation of the photon capture cross sections for th e electronic transitions gives the values of the order of magnitude of 10-(17)cm(2). The transient experiments have shown that the photocarr ier lifetimes in the crystals are of the order of 1000 sec.