Effect of channel implantation on the device performance of low temperature processed polycrystalline silicon thin film transistors

The characteristics of polycrystalline silicon thin film transistors (TFT s ) were experimentally investigated. Boron ions were implanted into the silicon films deposited by LPCVD, and then npn-type TFT s were fabricated on glass substrates using a low-temperature process of below 600°C. The current-voltage curves were measured before and after plasma hydrogenation. The off-state current at a gate voltage of 0 V after the hydrogenation decreased with increasing implantation dose, although the current before the hydrogenation was not affected. It was concluded from comparisions with calculations considering the density of trap states in the silicon energy gap that the dose dependence was attributed to the reduction of defects in the silicon films.