A PN gate polysilicon thin film transistor

We propose and fabricate a new polysilicon thin film transistor (poly-Si TFT) which exhibits the properties of an offset gated structure in the OFF state, while acting as a non-offset structure in the ON state. The fabrication process is compatible with the conventional non-offset poly-Si TFTs process and does not require any additional mask. Experimental results show that the leakage current of the new device is two orders of magnitude lower than that of the non-offset device, while the ON current of the new device is almost identical with that of the non-offset device. It is observed that the ON/OFF current ratio of the proposed poly-Si TFT is improved remarkably.