Hybrid insulator organic thin film transistors with improved mobility characteristics

Hybrid insulator pentacene thin film transistors (TFTs) were fabricated with thermally grown oxide and cross-linked polyvinylalcohol (PVA) including surface treatment by dilute ploymethylmethacrylate (PMMA) layers on n ⁺ doped silicon wafer. Through the optimization of SiO₂ layer thickness in hybrid insulator structure, carrier mobility was increased to above 35 times than that of the TFT only with the gate insulator of SiO ₂ at the same transverse electric field. The carrier mobility of 1.80 cm²/V-s, subthreshold swing of 1.81 V/decade, and I_on/ I_off current ratio > 1.10 × 10⁵ were obtained at low bias (less than -30 V) condition. The result is one of the best reported performances of pentacne TFTs with hybrid insulator including cross-linked PVA material at low voltage operation.