High Mobility P-Channel Thin-Film Transistors with Ultralarge-Grain Polycrystalline Silicon Formed Using Nickel-Induced Crystallization

In this study, p-channel polycrystalline silicon (poly-Si) thin-film transistors (TFTs) using an active layer of ultralarge-grain (ULG) silicon and multistack gate insulators of SiNx/SiO2 were fabricated and investigated. The ULG silicon thin films were formed by nickel (Ni)-induced crystallization and the average grain area of ULG silicon is 118 mu m(2). The field-effect mobility of p-channel ULG poly-Si TFTs was 111 cm(2)/(V.s), which can be sufficiently applied to high driving parts of display systems. The p-channel ULG poly-Si TFT has a low threshold voltage of -1.06 V, a high ON/OFF current ratio of 9.2 x 10(7), and a subthreshold swing of 0.27 V/decade. Moreover, the fabricated TFTs have stable characteristics under temperature and gate bias stress owing to the large grains and smooth surface. These results show that the ULG poly-Si TFTs are remarkably suitable for the application to a low power and high speed pixel-driving device in flat panel displays. (C) 2012 The Japan Society of Applied Physics