Influence of Si substrate preparation on surface chemistry and morphology of L-CVD SnO_2 thin films studied by XPS and AFM

摘要

Results of experimental studies of the influence of substrate preparation on the surface chemistry and surface morphology of the laser-assisted chemical vapour deposition (L-CVD) SnO_2 thin films are presented in this paper. The native Si(100) substrate cleaned by UHV thermal annealing (TA) as well as thermally oxidized Si(l 00) substrate cleaned by ion bombardment (IBA) have been used as the substrates. X-ray photoemission spectroscopy (XPS) has been used for the control of surface chemistry of the substrates as well as of deposited films. Atomic force microscopy (AFM) has been used to control the surface morphology of the L-CVD SnO_2 thin films deposited on differently prepared substrates. Our XPS shows that the L-CVD SnO_2 thin films deposited on thermally oxidized Si(100) substrate after cleaning with ion bombardment exhibit the same stoichiometry, i.e. ratio [O]/[Sn] -1.30 as that of the layers deposited on Si(100) substrate previously cleaned by UHV prolonged heating. AFM shows that L-CVD SnO_2 thin films deposited on thermally oxidized Si(100) substrate after cleaning with ion bombardment exhibit evidently increasing rough surface topography with respect to roughness, grain size range and maximum grain height as the L-CVD SnO_2 thin films deposited on atomically clean Si substrate at the same surface chemistry (nonstoichiometry) reflect the higher substrate roughness after cleaning with ion bombardment.