Adsorbed water on hydrothermal BaTiO3 films: work function measurements

We have investigated the time dependence of water adsorption on polycrystal line barium titanate films fabricated on silicon under hydrothermal conditi ons. X-ray photoelectron spectroscopy showed surface OH groups on the films but no molecular H2O. The time dependent behavior of water adsorption was investigated by measuring the work function changes with a Kelvin probe. Th e film response time for both increasing and decreasing humidity is less th an one minute. The typical amplitude change was about 0.05 eV for a 50% hum idity variation, with higher variations at lower humidity. (C) 1999 Elsevie r Science Ltd. All rights reserved.