Surface properties of atomically flat poly-crystalline SrTiO3

Abstract

Comparison between single- and the poly-crystalline structures provides essential information on the role of long-range translational symmetry and grain boundaries. In particular, by comparing single- and poly-crystalline transition metal oxides (TMOs), one can study intriguing physical phenomena such as electronic and ionic conduction at the grain boundaries, phonon propagation, and various domain properties. In order to make an accurate comparison, however, both single- and poly-crystalline samples should have the same quality, e.g., stoichiometry, crystallinity, thickness, etc. Here, by studying the surface properties of atomically flat poly-crystalline SrTiO3 (STO), we propose an approach to simultaneously fabricate both single- and poly-crystalline epitaxial TMO thin films on STO substrates. In order to grow TMOs epitaxially with atomic precision, an atomically flat, single-terminated surface of the substrate is a prerequisite. We first examined (100), (110), and (111) oriented single-crystalline STO surfaces, which required different annealing conditions to achieve atomically flat surfaces, depending on the surface energy. A poly-crystalline STO surface was then prepared at the optimum condition for which all the domains with different crystallographic orientations could be successfully flattened. Based on our atomically flat poly-crystalline STO substrates, we envision expansion of the studies regarding the TMO domains and grain boundaries.

Realization of atomically flat steps and terraces like surface of SrTiO3 (001) single crystal by hot water etching and high temperature annealing

“…Researchers are always looking for effective methods to achieve single terminated and atomically flat substrate surface. Till date, the work reported in the literature is based on NH 4 F buffered HF solution etching technique [14][15][16]. Buffered HF (BHF) is quite aggressive chemical etchant which leads to uncontrolled etching and introduces holes on the substrate surface that affects the thin film growth.…”

Tuning electromagnetic properties of SrRuO3 epitaxial thin films via atomic control of cation vacancies

“…High-quality heteroepitaxial SRO thin films were grown on atomically flat STO single crystalline substrates using PLE at 700 °C. 8,34 Laser (248 nm; Lightmachinery, IPEX 864) fluence of 1.5 J/cm 2 and repetition rate of 2 Hz were used. To systematically control the elemental vacancies in SRO, the thin films were grown under various P(O2), ranging from 10 -1 to 10 -3 Torr.…”

Ex-situ atomic force microscopy on the growth mode of SrRuO 3 epitaxial thin film

“…High-quality epitaxial SrRuO3 (SRO) thin film was grown on TiO2-terminated (001) SrTiO3 (STO) single crystalline substrates using pulsed laser epitaxy (PLE). [3,27] The miscut angle of STO substrate was ~0.1°. A laser (248 nm; IPEX 864, Lightmachinery) fluence of 1.5 J/cm 2 and repetition rate of 2 Hz was used.…”