Surface topographic (LEED, STM) and spectroscopic (ARUPS, XPS, STS) studies have been performed on the Si-terminated 6H-SiC(0001)-(<$E 3~times~3>) surface and Ag superstructures and ultrathin films on Si(001) and Si(111) surfaces, using a scanning tunneling microscope (STM) in ultrahigh vacuum. Our results confirm that a 2D epitaxial metal growth is favored on Si(001) at low temperatures and a solid, two-domain Ag(111) film has been achieved at coverage's as low as 10 ML. We have found that the films reveal a morphology with 3-dimensional features and with well defined honeycomb structure in between. An atomically flat <$E roman {Si(111) "/" Ag-( sqrt 3~times~sqrt 3 )R30 symbol Р}> surface has been modified by use of a scanning tunneling microscope (STM) in ultrahigh vacuum. High quality 6H-SiC(0001)-(<$E 3~times~3>) and <$E roman {Si(111) "/" Ag-( sqrt 3~times~sqrt 3 )R30 symbol Р}> 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)-(<$E 3~times~3>) surface with Hubbard gap 1 eV.