HIGH-QUALITY WIDE-GAP HYDROGENATED AMORPHOUS-SILICON FABRICATED USINGHYDROGEN PLASMA POSTTREATMENT

The hydrogen plasma post-treatment of hydrogenated amorphous silicon ( a-Si:H) has been investigated to obtain high-quality wide-gap films. T he hydrogen plasma treatment after film deposition substantially incre ases the hydrogen content and the optical gap of a-Si films without de teriorating their optoelectric properties within the range of treatmen t conditions in this study, where no microcrystallization of the films is observed. A photoconductivity of approximately 10(-5) OMEGA-1 cm-1 and a photosensitivity (the ratio of photoconductivity to dark conduc tivity) of > 10(6) are obtained for a-Si:H films with an optical gap o f > 1.7 eV from the (alphahnu)1/3 plot (> 2.0 eV from Tauc's plot) und er AM-1, 100 mW/cm2 illumination. An extremely high open circuit volta ge of > 1 V is obtained for an a-Si single-junction cell whose i-layer was fabricated using the hydrogen plasma treatment.