Pentacene thin-film transistors with Al2O3+x gate dielectric films deposited on indium-tin-oxide glass

We report on the fabrication of pentacene thin-film transistors (TFTs) with ${\mathrm{Al}}_2{\mathrm{O}}_{\text{3+x}}$ films as the gate dielectric that has been deposited on indium-tin-oxide glass by rf magnetron sputtering at room temperature. Although the ${\mathrm{Al}}_2{\mathrm{O}}_{\text{3+x}}$ was expected to show lower capacitance and breakdown field than stoichiometric ${\mathrm{Al}}_2{\mathrm{O}}_3,$ our pentacene TFTs with optimized thin ${\mathrm{Al}}_2{\mathrm{O}}_{\text{3+x}}$ gate dielectric exhibited a moderately high field mobility of 0.14 ${\mathrm{cm}}^2/\mathrm{V s},$ an outstanding subthreshold slope of 0.88 V/dec, and an on/off ratio over ${10}^6.$ Our work demonstrates that RT-deposited ${\mathrm{Al}}_2{\mathrm{O}}_{\text{3+x}}$ is a promising gate dielectric material for organic TFTs.