The effects of microcrystalline silicon film structure on low-high-low band-gap thin film transistor

The effects of hydrogenated microcrystalline silicon (mu c-Si:H) film with various crystalline factors on thin-film transistors (TFTs) with low-high-l ow band gap structure are studied. Compared to hydrogenated amorphous silic on (a-Si:H) TFT with conventional inverted-stagger structure, the device wi th mu c-Si:H film of high crystalline factor in the active channel depicts improved interfacial active layer near the gate insulator interface as well as the later-grown bulk active layer, resulting in improved device paramet ers including field effect mobility, threshold voltage, subthreshold swing and ON-current. While a-Si:H film of low crystalline factor and high-band-g ap is proposed for the source and drain offset regions in the new device to prevent the band-to-band tunneling, thus alleviates the high OFF-current i nherent in conventional mu c-Si:H thin-film transistors, resulting in an im proved ON/OFF current ratio. (C) 2000 Elsevier Science S.A. All rights rese rved.