Surface preparation of (110) oriented pure and Nb doped SrTiO3 single crystal substrates by microwave assisted hydrothermal method

• Realization of single termination along (110) orientation in pure and Nb doped SrTiO3 single crystal substrates.
• Microwave assisted hydrothermal alkaline etching is a universal method to realize single termination in SrTiO3 (110).
• Method is fast and does not need an ultra-high vacuum environment and long annealing time at high temperatures.
• Singly-terminated surface is of interest in the growth of layered multifunctional oxide heterostructures on SrTiO3 (110)

We present a simple and fast microwave-assisted hydrothermal etching process for (110) oriented pure and Nb doped SrTiO3 substrates. An annealing in oxygen atmosphere at 1000 °C after the etching in both deionized water and ammonia solution resulted in single-terminated surface for pure SrTiO3. In the case of niobium-doped substrates, such a surface could be realized only through etching in ammonia solution and subsequent annealing at 1100 °C. Observed step height of a/√ 2 nm in the topography by atomic force microscopy suggests [(SrTiO)4 +] or (O2)4 − termination. This realization of conducting/non-conducting, singly-terminated surface is of interest in the growth of layered multifunctional oxide heterostructures on SrTiO3 (110).