Inverted stagger hydrogenated amorphous silicon ͑a-Si: H͒ fork-shaped thin-film transistors ͑TFTs͒ were fabricated with a five-photomask process used in the processing of the active-matrix liquid crystal displays ͑AM-LCDs͒. 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.