Dember and photo-electromotive-force currents in silicon photoconductive detectors

Abstract

Dember and photo-electromotive-force (PEMF) currents are investigated in silicon photoconductive detectors both theoretically and experimentally. Dember photocurrents were found to dominate the response of high-purity silicon samples with top-surface electrodes to a moving interference pattern. The use of surface electrodes leads to shadowed regions beneath the electrodes, and Dember photocurrents appear under short-circuit conditions. A single-charge-carrier model of the Dember effect is in good qualitative agreement with experimental results. We also show theoretically that the PEMF effect in silicon is weak compared with other semiconductors because of its relatively high intrinsic conductivity.