Doubly Triggered Conductance Across Thin Zinc Oxysulfide Films

Abstract

Chemically resolved electrical measurements (CREM) of zinc oxysulfide (ZnOS) over-layers on gold show very poor conductance under either electrical or optical input signals, whereas simultaneous application of the two yields extremely high sample currents. The effect and its dependence on wavelength and electrical parameters is explained by the in-situ derived band diagram, in which a buffer level of charge traps cannot contribute directly to conductance, however amplifies the photoconductance by orders of magnitudes under sub-bandgap illumination. This AND-type doubly-triggered response proposes interesting applications and an answer to problems encountered in related optoelectronic devices.