Preparation of H-terminated Si surfaces and their characterisation by measuring the surface state density

• Published in: Applied surface science Vol. 104; pp. 107 - 112
• Main Authors: Angermann, H., Kliefoth, K., Flietner, H.
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01-09-1996
• ISSN: 0169-4332; 1873-5584
• DOI: 10.1016/S0169-4332(96)00128-6

H-terminated n- and p-type Si(111) surfaces are characterised by the large-signal field-modulated photovoltage technique (SPV) measuring the surface potential and the energetic distribution of surface states
D
it(
E). Using aqueous HF acid (HF) and buffered HF solution (BHF), different methods of chemical preparation were carried out characterising the treated surfaces repeatedly during the preparation process. The ideal H-terminated surface displays a very low density of surface states, comparable to well thermally oxidised surface and a significant decrease of HF-induced positive surface charge. The absence of these extrinsic defects indicates the successful preparation of H-terminated surfaces characterised by a nearly intrinsic surface state distribution. The surface state density was found to be mainly influenced by three aspects of the preparation: the doping type and the surface morphology of the substrate, the kind of chemical treatment, and the clean-room conditions as well. Very low surface state density (5 × 10
10 cm
−2 eV
−1 and about 2 × 10
10 cm
−2 eV
−1 on n-type and p-type Si surfaces, respectively) were obtained using BHF as final etching solution, when the treatment was carried out in N
2 atmosphere.