Hydrogen-terminated silicon surfaces produced by etching in solutions of HF were studied using photo-electron spectroscopy and low-energy electron diffraction. They were found to be remarkably free from contamination, locally ordered and electrically passivated. The hydrogen could be removed from the (100) surface by annealing in ultra-high vacuum at 520C. At that temperature, the initial (1 x 1) structure of the surface changes to a two domain (2 x 1) reconstruction and the Fermi level becomes pinned by surface states. The relationship between residual contamination and etching parameters such as time, concentration and crystallographic orientation of the sample was examined, together with the degradation of the hydride surface with exposure to various environments. This had shown that the contamination levels of the surface were sensitive to etching procedure, but with suitable care, a 5% non-aqueous HF solution was the optimum etchant.

A Photoemission Study of Passivated Silicon Surfaces Produced by Etching in Solutions of HF. J.M.C.Thornton, R.H.Williams: Semiconductor Science and Technology, 1989, 4[10], 847-51