Optical second harmonic generation (SHG) spectroscopy is used to probe Si(001) following thermal decomposition of diborane at the surface. Incorporation of boron (B) at second layer substitutional sites at H-free Si(001) intensifies and redshifts the E1 SHG spectral peak, while subsequent H termination further intensifies and blueshifts E1, in sharp contrast to the effect of bulk B doping or nonsubstitutional B. Ab initio pseudopotential and semiempirical tight binding calculations independently reproduce these unique trends, and attribute them to the surface electric field associated with charge transfer to electrically active B acceptors, and rehybridization of atomic bonds.

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We calculate the reflectance anisotropy and the reflectance-difference spectra for a clean Si͑100͒ surface and two hydrogen-͑H-͒ covered Si͑100͒ surfaces. The clean surface is a 2 ϫ 1 surface reconstruction, characterized by a tilted dimer formed between the two topmost Si atoms. One of the H-covered surfaces is a monohydride surface in which the two dangling bonds of the dimer are H saturated to give a flat dimer, and the other surface is a dihydride surface in which the H saturates each of the two dangling bonds leading to a bulk ideally terminated surface. The optical response is calculated with a pseudopotential framework using the localdensity-plus-scissors approximation. A "layer-by-layer" analysis of the response is implemented with the pseudopotential calculation.

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We present a review of the formalism and application of polarizable dipole models that have been used to calculate reflectance anisotropy spectra of semiconductor and metal surfaces and thin organic films.