Electronic structure modification of theKTaO3single-crystal surface byAr+bombardment

Abstract

Oxygen vacancies play an important role in controlling the physical properties of a perovskite oxide. We report alterations in the electronic properties of a cubic perovskite oxide, namely, ${\mathrm{KTaO}}_{3}$, as a function of oxygen vacancies. The conducting surface of the ${\mathrm{KTaO}}_{3}$ single-crystal substrate has been realized via ${\mathrm{Ar}}^{+}$ irradiation. The band gap changes as a function of conductivity which is controlled by irradiation time, indicating the formation of defect states. Kelvin probe force microscopy suggests a sharp increase in the work function upon ${\mathrm{Ar}}^{+}$ irradiation for a short period of time followed by a monotonic decrease, as we increase the irradiation time. Our experimental findings along with theoretical simulations suggest a significant surface dipole contribution and an unusual change in the electronic band line-up of ${\mathrm{KTaO}}_{3}$ due to oxygen vacancies.