Tunable threshold voltage and flatband voltage in pentacene field effect transistors

Charged interface states are introduced by UV-ozone treatment of a polymer gate dielectric, parylene, prior to deposition of the organic semiconductor, pentacene, thereby modifying the organic field effect transistor (OFET) operation from enhancement to depletion mode. Quasistatic capacitance-voltage measurements and the corresponding current-voltage characteristics show that the threshold voltage $V_T$ and flatband voltage $V_{\mathrm{FB}}$ can be shifted by over $+50\mathrm{V}$ , depending on the ozone exposure time. This work demonstrates that careful control of the semiconductor-insulator interface state densities is essential to $V_T$ and $V_{\mathrm{FB}}$ control and the fabrication of reliable OFET integrated circuits.