Subthreshold characteristics of submicrometer polysilicon thin film transistor

The subthreshold characteristics of both hydrogenated and unhydrogenated su b-micrometer polysilicon thin-film transistors have been investigated in de tail, The subthreshold slope of unhydrogenated TFTs becomes steeper at high er drain voltage. This is attributed to the floating-body effect that resul ts from the positive feedback between transistor current and impact ionizat ion current. The floating-body effect of poly-TFTs was found to relate to g rain size, drain voltage and hydrogenation. For the TFTs with larger poly-g rain, the floating-body effect was more obvious and appeared at lower drain bias. After hydrogenation, the floating-body effect was suppressed. Theref ore, the subthreshold swing of hydrogenated TFTs is continuously increasing with drain voltage. (C) 2001 Elsevier Science B.V. All rights reserved.