Characteristics of polycrystalline silicon thin-film transistors with electrical source/drain extensions induced by a bottom sub-gate

Abstract

Characteristics of polycrystalline silicon thin-film transistors (TFT) with source/drain extensions induced by a bottom sub-gate were explored, high on/off current ratio up to 10(7) could be achieved for both n- and p-channel devices. Nevertheless, the performance is significantly degraded by a marked increase of off-state leak-age current when the channel length is scaled below 1 mum. Moreover, a hump in the subthreshold current-voltage regime is observed. After careful analysis, it is found that the leakage current is strongly dependent on the field strength and is not a thermally activated process. A leakage path along the bottom interface of the poly-Si channel layer is proposed to explain these results.