Influence of thermal treatments on the sensitivity of CdSe thin films to oxygen ionosorption

Abstract

Oxygen ionosorption, i.e. chemisorption that induces changes in the electrical conductivity, has been studied by resistivity and Spectroscopie (XPS and AES) measurements, on vacuum-deposited thin polycrystalline CdSe films. The results of electrical resistance variations during isothermal adsorptions (Δ R-IA), isothermal desorptions (Δ R-ID) and temperature programmed desorptions (Δ R-TPD) are analysed on samples prepared under various conditions. The influence of cadmium and selenium excess and of surface oxidation of the film on its oxygen adsorption capacity is shown. XPS and AES measurements made after similar adsorptions and desorptions prove the correlation between oxygen presence on the film surface and the behaviour of electrical resistance variations: reversible or irreversible.