RETRACTED ARTICLE: Atom-vacancy hopping in ultra-high vacuum at room temperature in SrTiO3 (001)

Abstract

The diffusion at atomic scale is of considerable interest as one of the critical processes in growth and evaporation as well as a probe of the forces at an atomically flat reconstructed surface. This atomic-scale migration is critical to investigate in strontium titanate (SrTiO3) as it possesses the same status in oxide electronics as does silicon in ordinary electronics based on elemental semiconductors. Here we show that (001) terminated SrTiO3 reconstructed surface is atomically unstable enough to allow atom-vacancy hopping at room temperature. In this work, SrTiO3 (001) single crystal (7 × 2 × 0.5 mm) was sputtered (0.5 keV, 2.5 µA, 10 min) and annealed multiple times in ultra-high vacuum (UHV) and imaged using scanning tunneling microscope (STM). A relatively unstable surface was observed at low-temperature annealing and tip–surface interactions caused dislocation of mass at the surface. Both square and zig-zag nanolines were observed with atomic resolution where an atom-vacancy hopping was observed in a square diline while imaging at room temperature. The hopping was ceased when sample was annealed at higher temperature and a more compact network of nanolines was achieved. Graphic abstract

Interaction of 2-propanol with predominantly SrO- and TiO2-terminated SrTiO3(100) surfaces studied by vibrational sum frequency spectroscopy

“…In the 3rd step, the etched samples were baked at 1000 °C in air for 90 min to obtain a TiO 2 -terminated surface with large flat terraces. 22 Alternatively, the baking temperature was increased to 1200 °C and the duration extended to 72 h in order to obtain a SrO-terminated surface due to exdiffusion of Sr from the bulk. As a reference, a sample was also studied, which was prepared starting from the as-received crystal and skipping the annealing step, further referred to as the reference sample.…”