PREPARATION OF H-TERMINATED SI SURFACES AND THEIR CHARACTERIZATION BYMEASURING THE SURFACE-STATE DENSITY

H-terminated n- and p-type Si(lll) surfaces are characterised by the l arge-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), diff erent methods of chemical preparation were carried out characterising the treated surfaces repeatedly during the preparation process. The id eal H-terminated surface displays a very low density of surface states , comparable to well thermally oxidised surface and a significant decr ease of HF-induced positive surface charge. The absence of these extri nsic defects indicates the successful preparation of H-terminated surf aces characterised by a nearly intrinsic surface state distribution. T he surface state density was found to be mainly influenced by three as pects of the preparation: the doping type and the surface morphology o f the substrate, the kind of chemical treatment, and the clean-room co nditions as well. Very low surface state density (5 x 10(10) cm(-2) eV (-1) and about 2 x 10(10) cm(-2) eV(-1) on n-type and p-type Si surfac es, respectively) were obtained using BHF as final etching solution, w hen the treatment was carried out in N-2 atmosphere.