High-mobility BaSnO3 thin-film transistor with HfO2 gate insulator

Thin-film transistors have been fabricated using La-doped BaSnO3 as n-type channels and (In,Sn)2O3 as source, drain, and gate electrodes. HfO2 was grown as gate insulators by atomic layer deposition. The field-effect mobility, Ion/Ioff ratio, and subthreshold swing of the device are 24.9 cm2 V−1 s−1, 6.0 × 106, and 0.42 V dec−1, respectively. The interface trap density, evaluated to be higher than 1013 cm−2 eV−1, was found to be slightly lower than that of the thin-film transistor with an Al2O3 gate insulator. We attribute the much smaller subthreshold swing values to the higher dielectric constant of HfO2.