Quest for a pristine unreconstructed SrTiO₃(001) surface: An atomically resolved study via noncontact atomic force microscopy

Abstract

The surfaces of perovskite oxides affect their functional properties, and while a bulk-truncated (1 × 1) termination is generally assumed, its existence and stability is controversial. Here, such a surface is created by cleaving the prototypical SrTiO3(001) in ultrahigh vacuum, and its response to thermal annealing is observed. Atomically resolved noncontact atomic force microscopy (nc-AFM) shows that intrinsic point defects on the as-cleaved surface migrate at temperatures above 200 ◦C. At 400 ◦C-500 ◦C, a disordered surface layer forms, albeit still with a (1 × 1) pattern in low-energy electron diffraction (LEED). Purely TiO2-terminated surfaces, prepared by wet-chemical treatment, are also disordered despite their (1 × 1) periodicity in LEED.