Improved performance of pentacene OTFT with HfLaO gate dielectric by annealing in NH 3

Abstract

Pentacene organic thin-film transistors with HfLaO as gate dielectric were fabricated. The dielectric was prepared by sputtering method with a dielectric constant over 11, and hence the OTFTs could operate at a voltage less than 5 V. The dielectric was annealed in N 2, NO or NH 3 at 400 °C after sputtering to passivate the surface of the dielectric. The OTFT treated in NH 3 displayed higher carrier mobility, smaller sub-threshold swing, and lower 1/f noise than the OTFTs annealed in N 2 and NO respectively. SEM image indicated that pentacene inclined to form larger grains on the dielectric annealed in NH 3 than the dielectric annealed in N 2 or NO. The enhanced electrical performance of OTFTs annealed in NH 3 can be attributed to the improved interfacial characteristics between the organic film and the gate dielectric. ©The Electrochemical Society.