A hydrogen terminated Si(111) surface was prepared by etching in NH4F
solution and investigated by quantitative analysis of reflection high
energy electron diffraction data. The positions of the topmost silicon
atoms were found to be very close to their bulk-like sites. Their dis
placements can be estimated as -0.01 +/- 0.03 Angstrom for the top Si
layer and -0.01 +/- 0.03 Angstrom for the second layer. (C) 1998 Elsev
ier Science B.V. All rights reserved.