Improved performance of pentacene OTFT by incorporating Ti in NdON gate dielectric

Pentacene organic thin-film transistors (OTFTs) with high-k NdON gate dielectric incorporating different Ti contents are fabricated and their physical and electrical characteristics are studied. With appropriate Ti content, the OTFT with NdTiON as gate dielectric can achieve improved performance, e.g. a carrier mobility of 0.80 cm2/V·s, a small threshold voltage of -1.25 V, and a small sub-threshold swing of 0.13 V/dec. The AFM results of the pentacene layer and the dielectric layer reveal that incorporating Ti into NdON can obtain a smoother dielectric surface, which should be due to the suppressed hygroscopicity of Nd oxide caused by the Ti incorporation. Both the smoother dielectric surface and thus larger pentacene grains grown are responsible for the improved carrier mobility of the device.