Trend transformation of drain-current degradation under drain-avalanche hot-carrier stress for CLC n-TFTs

Abstract

Continuous-wave green laser-crystallized (CLC) single-grain-like polycrystalline silicon n-channel thin-film transistors (poly-Si n-TFTs) demonstrate the higher electron mobility and turn-on current than excimer laser annealing (ELA) poly-Si n-TFTs. Furthermore, high drain voltage accelerates the flowing electrons in n-type channel, and hence the hot-carriers possibly cause a serious damage near the drain region and deteriorate the source/drain (S/D) current. In this study, at high drain stress voltage, it appears that CLC TFT was degraded in the initial stress time (before 50 s), but the drain current was enhanced after 50 s. After 50 s stress time, the amount of grain boundary trap states near the drain side was getting large and the reflowing holes damaged the source region or injected into gate oxide near source side as well.