Growth Related Carrier Mobility Enhancement of Pentacene Thin-Film Transistors with High-k Oxide Gate Dielectric

Carrier mobility enhancement from 0.09 to 0.59cm₂/Vs is achieved for pentacene-based thin-film transistors (TFTs) by modifying the HfO₂ gate dielectric with a polystyrene (PS) thin film. The improvement of the transistor's performance is found to be strongly related to the initial film morphologies of pentacene on the dielectrics. In contrast to the three-dimensional island-like growth mode on the HfO₂ surface, the Stranski-Krastanov growth mode on the smooth and nonpolar PS/HfO₂ surface is believed to be the origin of the excellent carrier mobility of the TFTs. A large well-connected first monolayer with fewer boundaries is formed via the Stranski-Krastanov growth mode, which facilitates a charge transport parallel to the substrate and promotes higher carrier mobility.