INFLUENCE OF CRYSTALLINITY AND STRUCTURAL DEFECTS ON THE ELECTRONIC-PROPERTIES OF TRANSPARENT AND CONDUCTIVE SRTIO3 FILMS, AMORPHOUS OR CRYSTALLINE - COMPARATIVE-STUDY WITH ITO FILMS

The electronic properties of transparent and conductive SrTiO3 films, amorphous or crystalline, deposited by RF cathodic sputtering have been investigated and compared with those of amorphous or crystalline ITO deposits. The interactions between Ti3+:3d1(t2g) non-bonding states, occurring in crystalline SrTiO3 films that have a high oxygen deficiency, are responsible for the unexpectedly small band gap energy (E(g) = 2.5 eV). On the other hand, the band gap energy of amorphous SrTiO3 deposits (E(g) = 3.0 eV) is close to that reported for a single crystal of SrTiO3 (E(g) = 3.2 eV). Similar behaviour is not observed for ITO since amorphous and crystalline films have rather similar E(g) values (2.6 and 2.7 eV respectively). Finally, the work function of SrTiO3 films is smaller than that of ITO films.