Engineering the stoichiometry of a TiO2-rich SrTiO3(001) surface

We investigate the stoichiometry of a TiO2-rich SrTiO3(001) surface by depositing less than one monolayer of SrO under typical epitaxy conditions. We find that this deposition yields atomically flat islands on the step-and-terrace surface. All these islands have a height of exactly one full SrTiO3 unit cell, instead of the expected half unit cell. Reflection high-energy electron diffraction indicates that a reconstruction occurs on the bare surface, which disappears with SrO deposition. To explain these results, we propose a simple model with two key elements: (i) a TiO2 double layer must intrinsically be present on the as-prepared SrTiO3(001) surface, and (ii) with deposited SrO, this top layer rearranges itself to form islands with a height of one unit cell. (C) 2022 Author(s).

Automated summary

We investigated the stoichiometry of a TiO2-rich SrTiO3(001) surface by depositing less than one monolayer of SrO. Our results show that this deposition leads to atomically flat islands on the step-and-terrace surface with a height of exactly one full SrTiO3 unit cell. The presence of a TiO2 double layer on the as-prepared SrTiO3(001) surface and the rearrangement of the top layer with deposited SrO are proposed to explain these findings.