Enhanced negative ion formation in ultraviolet-laser irradiated silane: Implications for plasma deposition of amorphous silicon

Observation of enhanced electron attachment to ArF-excimer-laser irradiated silane is reported. Evidence is presented that highly excited electronic states of silane or its photofragments are responsible for the observed enhanced electron attachment. Since such electronically excited states may be produced in silane plasmas (by direct electron impact or by excitation transfer via metastable states of rare gases that are commonly used in silane discharges), the possible significance of this electron attachment process for negative ion formation in silane plasmas is indicated.