A high-voltage hydrogenated amorphous silicon thin film transistor (H-V a-Si:H TFT) with thick double layer gate insulator (∼0.95 μm) has been developed for reflective active-matrix cholesteric liquid crystal displays. The double layer gate insulator consists of 0.85 and 0.10 μm thick benzocyclobutene and hydrogenated amorphous silicon nitride, respectively. This HV a-Si:H TFT operates at the gate-tosource and drain-to-source biases up to 100V without any serious leakage current degradation and device breakdown.