Lublow, M.; Stempel, T.; Skorupska, K.; Muñoz, A.G.; Kanis, M.; Lewerenz, H.J.: Morphological and chemical optimization of ex-situ NH4F (40%) conditioned Si(111)-(1x1):H. Applied Physics Letters 93 (2008), p. 062112/1-3
10.1063/1.2972142
Abstract:
Synchrotron Radiation Photoelectron Spectroscopy was employed to investigate the chemical state of Si(111) surfaces upon anisotropic etching in concentrated NH4F solution. Minute amounts of oxidized silicon were detected and attributed to the fast Si-H-OH formation at atomic steps. With combined 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 SiO2/Si layer are removed by a two-step NH4F treatment leading to a terraced surface without triangular etch pits; subsequently, silicon in the Si1+/2+/3+ valence states is dissolved by HF (50%) while the surface topography is preserved.