Reversible conductivity changes in discharge‐produced amorphous Si

A new reversible photoelectronic effect is reported for amorphous Si produced by glow discharge of SiH₄. Long exposure to light decreases both the photoconductivity and the dark conductivity, the latter by nearly four orders of magnitude. Annealing above 150 °C reverses the process. A model involving optically induced changes in gap states is proposed. The results have strong implications for both the physical nature of the material and for its applications in thin‐film solar cells, as well as the reproducibility of measurements on discharge‐produced Si.