The temperature-induced evolution of the Si(111)–H(1 x 1) surface towards the (7 x 7)-reconstruction was studied by means of UPS, high-resolution electron energy loss spectroscopy and low-energy electron diffraction techniques. It was found that H atom desorption occurred at about 500C, and the full development of the (7 x 7)-phase, checked by both UPS and low-energy electron diffraction, occurred around 700C. In the valence band spectra, the (7 x 7)-related rest-atom peak was present already for annealing temperature of 465C, while the adatom-related peak starts to appear only around 600C and fully develops at 700C. A band bending was detected and its behaviour discussed in relation to the surface state evolution. In the first annealing steps, the desorption-induced defects cause the shift of the surface Fermi level and the consequent upwards band bending, which reaches the maximum value of 0.47eV for annealing to 465C. The subsequent evolution of the dangling-bond states into the (7 x 7) surface states determines the band bending decrease till 0.1eV.

Study of the Transition from the Ideal Si(111)–H(1 x 1) Surface to the (7 x 7) Reconstruction by HREELS, UPS and LEED. V.De Renzi, R.Biagi, U.del Pennino: Surface Science, 2002, 497[1-3], 247-53