Correlation between carrier mobility of pentacene thin-film transistor and surface passivation of its gate dielectric

The carrier mobility of pentacene thin-film transistor is studied by passivating the surface of its SiO2 gate dielectric in NH3 at different temperatures, namely, 900, 1000, 1100, and 1150 °C. Measurements demonstrate that the higher the annealing temperature, the higher the carrier mobility of the OTFT is. The device annealed at 1150 °C has a field-effect mobility of 0.74 cm2 /V s, which is 35% higher than that of the device annealed at 900 °C. Energy-dispersive x-ray analysis, scanning-electron microscopy, and atomic-force microscopy show that the higher carrier mobility should be due to more nitrogen incorporated at the gate-dielectric surface which results in more passivated dielectric surface and larger pentacene grains for carrier transport.