Low Temperature Physics: 37, 856 (2011); https://doi.org/10.1063/1.3672008 (10 pages)
Fizika Nizkikh Temperatur: Volume 37, Number 9-10 (September 2011), p. 1073-1084 ( to contents , go back )
Surface and electron structure of the 6H-SiC(0001)-(3×3) surface and ultrathin Ag films on Si(111) and Si(001)
Institute of Solid State Physics RAS, Chernogolovka, Moscow district 142432, Russian Federation
Received February 23, 2011
Surface topographic (LEED, STM) and spectroscopic (ARUPS, XPS, STS) studies have been performed on the Si-terminated 6H-SiC(0001)-(3×3) surface and Ag superstructures and ultrathin films on Si(001) and Si(111) surfaces, using a scanning tunneling microscope (STM) in ultrahigh vacuum. Our results confirm that a 2D epitaxial metal growth is favored on Si(001) at low temperatures and a solid, two-domain Ag(111) film has been achieved at coverage’s as low as 10 ML. We have found that the films reveal a morphology with 3-dimensional features and with well defined honeycomb structure in between. An atomically flat Si(111)/Ag-(√3̅×√3̅)R30° surface has been modified by use of a scanning tunneling microscope (STM) in ultrahigh vacuum (UHV). High quality 6H-SiC(0001)-(3×3) and Si(111)-Ag(√3̅×√3̅)R30° over structures have been prepared and studied by means of ARUPS, XPS and LEED. The local density of states proportional to the normalized differential conductivity (dI / dV )/(I / V ) vs V spectra show a distinct bands of empty (–0.6 eV) and filled (0.65 eV) sites separated by 1.2 eV, for both areas. The results support a Mott–Hubbard-type model as used for the calculation of the density of states of 6H-SiC(0001)-(3×3) surface with Hubbard gap 1 eV.
PACS: 62.23.Eg Nanodots;
Key words: low-energy electron diffraction, visible ultraviolet and x-ray photoelectron spectroscopy, scanning tunneling spectroscopy, surface electrical transport (surface conductivity, surface recombination, etc.), silicon, silver.