Photoconductivity Stability Improvement in Hydrogenated Amorphous Silicon by Ultraviolet Illumination

Abstract

AbstractWe observe improved photoconductivity stability against light-soaking in hydrogenated amorphous silicon thin films as a result of an ultraviolet (UV) illumination and etch treatment. UV-etch treated samples begins with red-light photoconductivities inferior to that of a control sample which is only etched. After less than an hour of 1 sun red light-soaking, the photoconductivity of the etched-only control falls below that of the UV-etch treated sample. After 2 to 3 days light soaking, the UV-etch films can have a photosensitivity 20 to 38% above their control. We observe no corresponding improvement of defect optical absorption by constant photocurrent method spectroscopy. The UV-etch treatment also produces small improvements in the stabilized open-circuit voltage of Schottky barier solar cells. We speculate that mobile hydrogen produced during UV illumination is penetrating the film and improving stability.