By simultaneous surface photovoltage (SPV) as well as ultraviolet-visible (UV-Vis) and Fourier-transform infrared (FTIR) spectroscopic ellipsometry (SE) measurements on H-terminated Si(111) and Si(100) wafers as well as muc-Si:H surfaces directly after preparation and after storage in clean-room air, correlations were established between the preparation-induced surface morphology and the stability of the surface passivation against native oxidation. It was shown that the progression of the initial oxidation phase on differently prepared H-terminated and etched surfaces strongly depends on the remaining surface microroughness and interface state density. (C) 2002 Elsevier Science B.V. All rights reserved.