SPECTROSCOPIC CHARACTERIZATION OF ELECTRON-BEAM EVAPORATED V2O5 THIN-FILMS

Thin films of vanadium pentoxide (V2O5) were prepared by electron beam evaporation at different deposition temperatures. The chemical compos ition and structural and optical properties were investigated employin g spectroscopic techniques, viz. X-ray photoelectron spectroscopy (XPS ), inductively coupled plasma atomic emission spectroscopy (ICP-AES), infrared spectroscopy (IR), Raman spectroscopy (RS) and optical spectr oscopy (OS). The influence of deposition temperature on the film prope rties were deduced from the spectroscopic measurements. The room tempe rature (303 K) electron-beam evaporated V2O5 films were nearly stoichi ometric. The films formed at elevated temperatures were sub-stoichiome tric as revealed (XPS) from the shift of the V(2p(3/2)) emission peak, the broadening of full width at half maximum (FWHM) and the decrease in the O(ls):V(2p(3/2)) ratio. The shift of vanadyl mode in the IR and Raman spectra, decrease of the optical band gap and increase in the n ear-infrared-broad band absorption also supported the sub-stoichimetri c nature. Annealing of the films formed at T-s similar to 553 K in an oxygen atmosphere (a partial pressure of 10(-4) mbar) at 693 K led to the existence of vanadium in its highest oxidation state. (C) 1997 Els evier Science S.A.