Scanning tunneling microscopy study of the hydrogen-terminated n- and p-type Si 001/surfaces

We have investigated hydrogen-passivated Si 001.surfaces with various doping conditions using X-ray photoelectron spectroscopy XPS., scanning tunneling microscopy STM.and scanning tunneling spectroscopy STS.. It is found that Si 2p peak energies of XPS for the hydrogen-passivated surfaces depend on the doping conditions while Si 2p XPS peaks for reconstructed surfaces after annealing them at 7008C always have the same binding energies without depending on the doping conditions. This suggests that the surface Fermi level on the hydrogen-passivated Si 001. surface is unpinned. STMrSTS measurements reveal that a shoulder originating from a dopant level exists in the current–voltage I–V.curve obtained by STS. We discuss the possibility to obtain bulk electronic characteristics of Si through its hydrogen-passivated surface with the use of STMrSTS. q1998 Elsevier Science B.V. All rights reserved.