Morphological and chemical optimization of ex situ NH4F (40%) conditioned Si(111)-(1 x 1) : H

Synchrotron radiation photoelectron spectroscopy was employed to investigate the chemical state of Si(111) surfaces upon anisotropic etching in concentrated NH(4)F solution. Minute amounts of oxidized silicon were detected and attributed to the fast Si-H-OH formation at atomic steps. Combining in situ optical and scanning probe techniques, consecutive chemical treatments were developed to achieve optimized morphological and chemical surface properties. Native oxides and a stressed SiO(2)/Si layer are removed by a two-step NH(4)F treatment leading to a terraced surface without triangular etch pits; subsequently, silicon in the Si(1+/2+/3+) valence states is dissolved by HF (50%) while the surface topography is preserved. (C) 2008 American Institute of Physics.