In situ photoluminescence study of plasma-induced damage at the a -Si:H/c-Si interface

In situ photoluminescence combined with optical emission spectroscopy, effective carrier lifetime, radio-frequency (RF) and self-bias potential measurements has been used to study plasma-induced damage at the a-Si:H/c-Si interface. Passivated crystalline silicon wafers were exposed to Ar, H₂, and Ar-H₂ RF plasmas using the same value of RF power and pressure in the range of 80-100 mTorr. The substrate temperature during the plasma exposure was room temperature or 200 °C. It is found that Ar-H₂ plasma has the most detrimental effect on the photoluminescence intensity/effective carrier lifetime which correlates well with its UV spectrum. After plasma exposure, surface passivation can be recovered by thermal annealing - an effect similar to that observed in the case of light-induced degradation of a-Si:H.