High-Quality Wide-Gap Hydrogenated Amorphous Silicon Fabricated Using Hydrogen Plasma Post-Treatment

Abstract

The hydrogen plasma post-treatment of hydrogenated amorphous silicon (a-Si:H) has been investigated to obtain high-quality wide-gap films. The hydrogen plasma treatment after film deposition substantially increases the hydrogen content and the optical gap of a-Si films without deteriorating their optoelectric properties within the range of treatment conditions in this study, where no microcrystallization of the films is observed. A photoconductivity of ∼10 -5 Ω -1 cm -1 and a photosensitivity (the ratio of photoconductivity to dark conductivity) of >10 6 are obtained for a-Si:H films with an optical gap of >1.7 eV from the (α h ν) 1/3 plot (>2.0 eV from Tauc's plot) under AM-1, 100 mW/cm 2 illumination. An extremely high open circuit voltage of >1 V is obtained for an a-Si single-junction cell whose i-layer was fabricated using the hydrogen plasma treatment.