Pentacene-thin film transistors with ZrO2 gate dielectric layers deposited by plasma-enhanced atomic layer deposition

The effect of the dielectric constant and surface roughness of gate dielectrics on the electrical performance of pentacene-thin-film transistor (TFT) was investigated using high-kappa ZrO2 films deposited by plasma-enhanced atomic layer deposition. The dielectric constant of ZrO2 (kappa(ZrO2)) was in the range of 15.6-33.0, and the surface roughness was increased with kappa(ZrO2) in the presently reported devices. Threshold voltage and subthreshold swing were effectively reduced with increasing kappa(ZrO2) and were remarkably low, with values of -0.42 V and 0.15 V/dec, respectively, when kappa(ZrO2) = 33.0. To the contrary, the carrier mobility was determined by the surface roughness of ZrO2 gate dielectrics. (c) 2007 The Electrochemical Society.