STRUCTURE OF HYDROGEN ON THE SI(100) SURFACE IN THE (2X1)-H MONOHYDRIDE, (1X1)-H DIHYDRIDE, AND C(4X4)-H PHASES

The hydrogen atom adsorption sites on the Si{100} surface in the (2 X 1)-H monohydride, (1 X 1)-H dihydride, and c(4 X 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 Ar+ as a function of crystal azimuthal angle and Ne atoms scattered by a 4-keV 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.