CHARACTERIZATION OF CHEMICALLY PREPARED SI-SURFACES BY UV-VIS AND IR SPECTROSCOPIC ELLIPSOMETRY AND SURFACE PHOTOVOLTAGE

Roughness and oxide coverage of silicon (Si) surfaces after various ch emical treatments were investigated using ex situ spectroscopic ellips ometry (SE) both in the ultraviolet-visible (uv-vis) and in the infrar ed (IR) spectroscopic region. For control and optimization of electron ic interface properties the large-signal field-modulated surface photo voltage technique was used for contactless measurement of the surface band-bending and the energetic distribution of interface states D-it(E ). Applying a special hydrogen (H)-termination procedure, very smooth Si(111) surfaces without any native oxide coverage were prepared, char acterized by a U-shaped intrinsic surface state distribution and very low surface state density D-it,D-min < 3 x 10(10) cm(-2) eV(-1). On th ese surfaces the resonant absorbance due to the Si-H bonds was observe d directly by IR ellipsometry. By comparing the SE data and interface state distributions of differently treated silicon surfaces the densit y of intrinsic and extrinsic surface states was correlated to the surf ace roughness and oxide coverage. (C) 1997 Elsevier Science B.V.