Oxide materials are important candidates for the next generation of electronics due to a wide array of desired properties which they can exhibit alone or when combined with other materials. While SrTiO3 (STO) is often considered a prototypical oxide, it too hosts a wide array of unusual properties including a two dimensional electron gas (2DEG) which can form at the surface when exposed to UV light. Using layer-by-layer growth of high quality STO films, we show that the 2DEG only forms with the SrO termination and not with the TiO2 termination, contrary to expectation. This behavior is similarly seen in BaTiO3 (BTO), in which the 2DEG is only observed for BaO terminated films. These results will allow for a deeper understanding, and better control, of the electronic structure of titanate films, substrates and heterostructures.
@article{arxiv.1811.12652,
title = {Dichotomy of the Photo Induced 2-Dimensional Electron Gas on SrTiO$_3$ Surface Terminations},
author = {Slavko Rebec and Tao Jia and Hafiz Sohail and Makoto Hashimoto and Donghui Lu and Zhixun Shen and Robert Moore},
journal= {arXiv preprint arXiv:1811.12652},
year = {2019}
}