Asymmetric electrical properties of fork a-Si:H thin-film transistor and its application to flat panel displays

Abstract

Inverted stagger hydrogenated amorphous silicon (a-Si:H) fork-shaped thin-film transistors (TFTs) were fabricated with a five-photomask process used in the processing of the active-matrix liquid crystal displays (AM-LCDs). We investigated the asymmetric electrical characteristics of a fork-shaped a-Si:H TFT under different bias conditions. To extract the electrical device parameters, we developed asymmetric geometrical factors. Current-voltage measurements indicate that the ON-OFF current ratio of fork TFT can be enhanced significantly by choosing the outer electrode as the drain, while the field-effect mobility and threshold voltage have the identical values when different drain bias conditions are used. Finally, we developed concepts of its possible application to AM-LCDs.