Hot carrier degradation in low temperature processed polycrystalline silicon thin film transistors

The effects of hot carrier degradation on the characteristics of low temperature processed polycrystalline silicon thin film transistors (poly-Si TFTS) have been studied for devices formed by several different technologies. In all cases the degradation is found to result from the formation of interface acceptor states in the upper half of the band gap, and to donor states near to mid-gap. The worst case conditions for degradation are identified, and device reliability lifetime is deduced. No additional effects are found to arise from AC stressing, and degradation in NMOS shift registers is found to be consistent with the results of simple stress tests.