Effects of Oxynitride Buffer Layer on the Electrical Characteristics of Poly-Silicon TFTs Using Gate Dielectric

In this paper, we have developed high-k Pr₂O₃ poly-Si thin-film transistors (TFTs) using different N₂O plasma power treatments. High-k Pr₂O₃ poly-Si TFT devices using a 200-W plasma power exhibited better electrical characteristics in terms of high effective carrier mobility, high driving current, small subthreshold slope, and high I_ON/I_OFF current ratio. This result is attributed to the smooth Pr₂O₃/poly-Si interface and low interface trap density. Pr₂O₃ poly-Si TFT with a 200-W N₂O plasma power also enhanced electrical reliabilities such as hot carrier and positive bias temperature instability. All of these results suggest that a high-k Pr₂O₃ gate dielectric with the oxynitride buffer layer is a good candidate for high-performance low-temperature poly-Si TFTs.