A Hybrid a-Si and Poly-Si TFTs Technology for AMOLED Pixel Circuits

A hybrid thin film transistor (TFT) technology is proposed and demonstrated, which features a simultaneous fabrication of amorphous silicon (a-Si) TFTs with low off-current and polycrystalline silicon (poly-Si) TFTs with high carrier mobility on one substrate in one single process. For the a-Si TFT fabrication, the active film is the as-deposited LPCVD a-Si film, whereas, for the poly-Si TFT fabrication, the poly-Si active film is the locally crystallized LPCVD a-Si film. The localized crystallization is realized via using metal-induced lateral crystallization (MILC) method. This proposed technology is applicable to active-matrix organic light-emitting diode (AMOLED) pixel circuits where switching TFTs and driving TFTs are required to be with low off-current and high on-current, respectively.