In-plane structure of an arsenic-adsorbed Si(001) surface probed with grazing-angle x-ray standing waves

Abstract

The grazing-angle x-ray standing-wave technique has been employed for in-plane structure determination of an arsenic-deposited Si(001) surface with $1\ifmmode\times\else\texttimes\fi{}2$ and $2\ifmmode\times\else\texttimes\fi{}1$ domains. Experimental data were collected using the (220), $(2\ifmmode\bar\else\textasciimacron\fi{}20),$ and (040) Bragg planes nearly perpendicular to the surface under UHV conditions. Three arsenic-emission profiles were fit by calculations based on the x-ray dynamical theory for perfect crystals. The data analysis allows us to limit the possible ranges of an As-As dimer bond length L, an in-plane root mean-square thermal vibrational amplitude $\sqrt{〈{u}_{\ensuremath{\parallel}}^{2}〉},$ and the two domain fractions, ${M}_{1}$ and ${M}_{2}.$ The ranges of the structural parameters, such as L and $\sqrt{〈{u}_{\ensuremath{\parallel}}^{2}〉},$ are consistent with other works. In particular, L and a two-domain area ratio ${M}_{2}{/M}_{1}$ are restricted within the narrow ranges from 2.57 to 2.52 \AA{}, and from 1.35 to 1.29, respectively. Assuming domains are perfectly ordered, it is found that $L=2.52\ifmmode\pm\else\textpm\fi{}0.05\AA{},$ $\sqrt{〈{u}_{\ensuremath{\parallel}}^{2}〉}=0.22\ifmmode\pm\else\textpm\fi{}0.07\AA{},$ ${M}_{1}=0.44\ifmmode\pm\else\textpm\fi{}0.07,$ and ${M}_{2}=0.56\ifmmode\pm\else\textpm\fi{}0.07.$