Abstract:
Chemisorption of oxygen on the surface of the grains of ZnO powder layers mainly controls
the photoconductivity. The adsorption of oxygen ions is regarded as a chemical reaction at the
interface and involves oxygen from the gas atmosphere and electrons from the metal oxide. The
changes in the conductivity of ZnO-layers calculated on this basis are in fair agreement with the
experimental results. At low light levels deviations from the theory are observed which result from
an “ overdepletion ” of the conductivity controlling regions in the powder layer. Considering a
ZnO layer as a secondary photoconductor has allowed the calculation of a maximum photosensitivity
for such layers.
