Depth profiling and the effect of oxygen and carbon on the photoelectricalproperties of amorphous silicon films deposited using tungsten wire filaments

Infrared spectroscopic data are correlated here together with conductivity results, transient photoconductivity measurements and fundamental absorptio n data in an attempt to understand the physical processes involved in the g rowth of tungsten hot-wire deposited hydrogenated amorphous silicon. Film s urface growth processes initially involve diffusing thermally dissociated r adicals, with a subsequent additional contribution from evaporated silicon species. We show how changing processes at the heated wire surface, surroun ded by silane gas, affect the electronic and structural properties of the h ydrogenated amorphous silicon produced. Depth profiling by chemical etching reveals substantial variations in the level of contamination and in the el ectronic structure throughout the film. (C) 2001 Elsevier Science B.V. All rights reserved.