Performance enhancement of offset gated polysilicon thin-film transistors

Simple offset gated n-channel polysilicon thin film transistors (TFTs) of channel length L = 10 mum were investigated in relation to the intrinsic offset length DeltaL and the polysilicon quality. For at DeltaL less than or equal to 1 mum, the device parameters such as threshold voltage, subthreshold slope and field effect mobility are improved, while the leakage current remains unchanged. In TFTs with DeltaL > 1 mum, the leakage current decreases with increasing the offset length. When the polysilicon layer is of high quality (large grain size and low intra-grain defect density), the leakage current is completely suppressed without sacrificing the on-current in TFT's with offset length of 2 mum.