Photoconductive and Photovoltaic Properties in Cadmium Bismuth Aluminate Glasses

Photo-induced phenomena such as photoconductive and photovoltaic effects were investigated for the glasses in CdO-Bi(2)O(3)-Al(2)O(3) system. Photoconductive effect was characterized by a slow decay of photocurrent (persitent photoconductivity). The decay rate decreased with increasing CdO content and decreasing Bi(2)O(3) content. Photovoltage was very small at room temperature but increased to an obvious value on heating. The photoconductivity and photovoltage were increased with CdO content and enhanced by heat treatment in air. The valence band spectra of X-ray photoelectron spectroscopy showed that the hybridization of Cd 4d and O 2p orbitals increases with decreasing Bi(2)O(3) content and increasing CdO content in the glasses. As the results maximum tends to flat. This type of band structure inhibits the rapid recombination of electrons and holes. The persistent photoconductivity of the glasses may be attributed to deep energy level of DX centers. Deep energy levels of the glasses are able to prevent the recombination because they have a repulsive barrier for both electron emission and capture.