SCANNING-TUNNELING-MICROSCOPY STUDY OF THE HYDROGEN-TERMINATED N-TYPEAND P-TYPE SI(001) SURFACES

We have investigated hydrogen-passivated Si(001) surfaces with various doping conditions using X-ray photoelectron spectroscopy (XPS), scann ing tunneling microscopy (STM) and scanning tunneling spectroscopy (ST S). It is found that Si 2p peak energies of XPS for the hydrogen-passi vated surfaces depend on the doping conditions while Si 2p XPS peaks f or reconstructed surfaces after annealing them at 700 degrees C always have the same binding energies without depending on the doping condit ions. This suggests that the surface Fermi level on the hydrogen-passi vated Si(001) surface is unpinned. STM/STS 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 bul k electronic characteristics of Si through its hydrogen-passivated sur face with the use of STM/STS. (C) 1998 Elsevier Science B.V. All right s reserved.