Structure of hydrogen on the Si{100} surface in the (2×1)-H monohydride, (1×1)-H dihydride, and<i>c</i>(4×4)-H phases

Abstract

The hydrogen atom adsorption sites on the Si{100} surface in the (2\ifmmode\times\else\texttimes\fi{}1)-H monohydride, (1\ifmmode\times\else\texttimes\fi{}1)-H dihydride, and c(4\ifmmode\times\else\texttimes\fi{}4)-H phases have been studied by time-of-flight (TOF) scattering and recoiling spectrometry. The experimental procedures and methods employed were similar to those of paper I [Y. Wang, M. Shi, and J. W. Rabalais, Phys. Rev. B 48, 1678 (1993)]. Structural analyses were obtained by measuring TOF spectra of neutrals plus ions for H atoms recoiled from 4-keV ${\mathrm{Ar}}^{+}$ as a function of crystal azimuthal angle and Ne atoms scattered by a 4-keV ${\mathrm{Ne}}^{+}$ beam as a function of beam incident angle to the surface. Through the use of calibrated shadow cones, the data provide a direct determination of the hydrogen atom coordinates relative to the outermost layer of silicon atoms. Si-H bond lengths and bond angles are calculated from these coordinates.