Changes of surface potentials of Hex. CdS single crystals and powders caused by irradiation of visible light were investigated. Their dependence on wavelengths, decay after irradiation, superposition of the two beams of different wavelengthsand effects of heat treatment were measured in the ordinary atmosphere.
From the qualitative discussions about these results, it may be expectedthat the photosensitive surface barriers exist in Hex. CdS crystals.