Quasi-two-dimensional electron systems (q-2DES) are formed in various hetero-structures, including oxide interfaces. Oxygen vacancies (OVs) in oxides like SrTiO3 are known to produce electronic carriers. A novel way to produce SrTiO3−δ on the surface using a low-energy H2 plasma is shown here. It results in a q-2DES with mobility as high as μ∼20,000cm2V−1s−1, displaying quantum oscillations in magneto-resistance. We can achieve a sharper or weaker confinement potential by adjusting the process pressure. The system with sharper confinement displays clearer quantum oscillations and Kondo-like temperature dependence of resistance. OVs close to the surface behaving like a correlated Anderson impurity is responsible for the Kondo behaviour. Quantum oscillations are less prominent in the weakly confined system. A cross-over from weak-localization to anti-localization with temperature is seen, but no Kondo behavior. The process also results in a transparent conductor amenable to lithographic patterning. This conductor's standard figure of merit is comparable to poly-crystalline ITO films in the visible regime and extends with similar performance into the λ∼1.5μm telecommunication wavelength.
@article{arxiv.2207.12933,
title = {Engineering Surface Oxygen Vacancies in $\mathrm{SrTiO_3}$ to Form a High Mobility and Transparent Quasi Two dimensional Electron System},
author = {Shyam Sundar Yadav and Shelender Kumar and Pankaj Kumar and Ananth Venkatesan},
journal= {arXiv preprint arXiv:2207.12933},
year = {2022}
}