The photoeffect in powdered semiconductors

A simple technique makes possible the measurement of spectral dependences of the photoeffect and photoeffect time relaxations in powdered semiconductors. Our qualitative explanation of the photoeffect in powdered semiconductors is presented. The photoeffect onsets observed in CdS, GaAs, Ge, Si, and ZnO are in good agreement with the energy gaps of these materials. Both the spectral dependences and the time relaxations of the photoeffect are strongly dependent on the quality of the particle surface. The extrinsic photoeffect was observed in GaAs and CdS.