Experimental evidence of grain-boundary related hot-carrier degradation mechanism in low-temperature poly-Si thin-film-transistors

Unique degradation behavior in the transfer characteristics was observed in low-temperature (LT) polycrystalline silicon (poly-Si) thin-film-transistors (TFTs) after hot carrier stress. To understand the degradation mechanism, stress-induced-resistance R/sub l/ is introduced, which is connected with channel resistance R/sub channel/ in series. A possible origin of R/sub l/ is potential barriers caused by negative charges generated at grain boundaries. Furthermore, using devices with a different density of grain boundary, the grain-boundary related degradation mechanism is experimentally demonstrated. Reducing the grain boundary density is effective for improving the hot carrier reliability.