Effect of low energy oxygen ion beam on optical and electrical characteristics of dual ion beam sputtered SnO2 thin films

Tin dioxide thin films were prepared by dual ion beam sputtering on various substrates. The Sn and the SnO2 targets were sputtered with 1000 eV. 1.5-2 .0 mA/cm(2) argon ion beam, and the water-cooled substrates were simultaneo usly bombarded with oxygen ion beam of 0-200 eV and 200 mu A/cm(2). All of oxygen-assisted thin films showed high transparency and bulk-like refractiv e indices, while the sputtered film without bombardment had relatively poor transmittance, As the bombarding energy increased, the absorption edge shi fted to lower wavelength and the optical band gap energy increased to a max imum value of 4.21 eV, Four-point-probe measurement nt showed that the resi stivity of as-deposited films depended strongly on target material and bomb ardment energy. After heat treatment, the optical band gap and the resistiv ity showed similar behavior and had their maxima after annealing at 400 deg rees C. (C) 1999 Elsevier Science S.A. All rights reserved.