Reconstructions on the polarSrTiO3(110) surface: Analysis using STM, LEED, and AES

Abstract

Scanning tunneling microscopy, Auger electron spectroscopy (AES), and low energy electron diffraction are used to investigate $0.5\phantom{\rule{0.3em}{0ex}}\mathrm{wt}\phantom{\rule{0.2em}{0ex}}%$ Nb doped $\mathrm{Sr}\mathrm{Ti}{\mathrm{O}}_{3}$ (110) samples, which are annealed in ultrahigh vacuum. An $(n\ifmmode\times\else\texttimes\fi{}1)$ family of reconstructions constituting $(3\ifmmode\times\else\texttimes\fi{}1)$, $(4\ifmmode\times\else\texttimes\fi{}1)$, and $(6\ifmmode\times\else\texttimes\fi{}1)$ periodicities form on the surface at varying annealing temperatures. Wood's notation of the reconstructions is defined such that the first integer represents the multiple of the bulk terminated periodicity in the [001] direction and the second digit shows the multiple of the periodicity in the [$1\overline{1}0$] direction. AES reveals that all the reconstructions are O deficient, but the $(4\ifmmode\times\else\texttimes\fi{}1)$ is also Ti enriched and the $(6\ifmmode\times\else\texttimes\fi{}1)$ is Sr enriched with respect to stoichiometry. The $(3\ifmmode\times\else\texttimes\fi{}1)$ surface possesses step edges which are decorated with a $(1\ifmmode\times\else\texttimes\fi{}4)$ reconstruction on the upper terrace. Similarly, step edges on the $(6\ifmmode\times\else\texttimes\fi{}1)$ surface often possess small regions of $(1\ifmmode\times\else\texttimes\fi{}2)$ reconstruction on the lower terrace. Step heights are always found to be equivalent to integer multiples of the distance between two similar {110} planes (the ${d}_{110}$ lattice parameter, $0.28\phantom{\rule{0.3em}{0ex}}\mathrm{nm}$).