A Center-Offset Polycrystalline-Silicon Thin-Film Transistor With ${\rm n}^{+}$ Amorphous-Silicon Contacts

We have studied a bottom-gate polycrystalline-silicon thin-film transistor (poly-Si TFT) with amorphous-silicon (a-Si) n⁺ contacts and center-offset gated structure, where intrinsic poly-Si is used in the center-offset region. The fabrication process is compatible with the conventional a-Si TFT with addition of thermal annealing for crystallization of a-Si. The bottom-gate poly-Si TFT with a 5-mum offset length exhibited a field-effect mobility of 18.3 cm²/V middots and minimum OFF-state current of 2.79 times 10^-12A/mum at V_ds= 5 V. The leakage currents are two orders of magnitude lower than those of a nonoffset TFT with mobility drop from 23.8 to 18.3 cm²/ Vmiddots.