Leed investigation of (111) oriented Si, Ge and GaAs surfaces following pulsed laser irradiation

摘要

The low energy electron diffraction (LEED) patterns obtained from clean (111) oriented Si, Ge, and GaAs single crystals subsequent to their irradiation with the output of a pulsed ruby laser in an ultra-high vacuum (UHV) environment suggest that metastable (1 x 1) surface structures are produced in the regrowth process. Conventional LEED analyses of the Si and Ge surfaces suggest that they terminate in registry with the bulk but that the two outermost interlayer spacings differ from those of the bulk. For the case of Si these changes are a contraction of 25.5 +- 2.5% and an expansion of 3.2 +- 1.5% between the first and second and second and third layers, respectively.