Nanoscale composition analysis of atomically flat SrTiO3(001) by friction force microscopy

Abstract

Friction force microscopy (FFM) was used to distinguish the different surface terminations on the nanoscale on atomically flat SrTiO3(001) surfaces, obtained by a combination of ultrasonic agitation and subsequent annealing in air at 1000 °C. The surface exhibits atomically flat terraces and sharp steps whose height is 0.2 nm, corresponding to half the height of a unit cell of SrTiO3, or a single atomic layer, where strong friction contrast appears. A compositional analysis of the topmost surface by coaxial-impact-collision ion-scattering spectroscopy (CAICISS) indicated that the friction contrast corresponded to different surface terminations, namely, the SrO and TiO2 layer as a topmost surface, where the TiO2 domain was dominant. This is further supported by the correlation between the compositional Sr/Ti ratio and the area ratio which was observed by CAICISS and FFM, respectively.