Ultraviolet photoconduction of TiO2/Ge bilayer film

Photoconductive TiO2/Ge bilayer films sensitive to Ultraviolet light are pr epared by subsequent evaporations on quartz substrates at temperatures abov e 300 degreesC for Ge and at room temperatue for TiO2. Two threshold photon energies characterize the photoconduction. One is the threshold of 2.5 eV when the photocurrent I-p begins to rise sharply irrespective of air ambien ce and the other is the threshold of 4.0 eV when I-p begins to decrease in vacuum. The origin of photoconduction is explained in terms of photoassiste d dissociation reaction of unbound oxygen species which are induced at the interface in the non equilibrium junction of Ge and TiO2 layers. The effect of ethanol gas exposure to the sample on photoconduction is examined spect roscopically.