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

Thin-film transistors have been fabricated using La-doped BaSnO 3 as n-type channels and (In,Sn) 2 O 3 as source, drain, and gate electrodes. HfO 2 was grown as gate insulators by atomic layer deposition. The field-effect mobility, I on / I off ratio, and subthreshold swing of the device are 24.9 cm 2 V −1 s −1 , 6.0 × 10 6 , and 0.42 V dec −1 , respectively. The interface trap density, evaluated to be higher than 10 13 cm −2 eV −1 , was found to be slightly lower than that of the thin-film transistor with an Al 2 O 3 gate insulator. We attribute the much smaller subthreshold swing values to the higher dielectric constant of HfO 2 .