Advanced functional oxide thin films grown by pulsed-laser deposition

Abstract

Pulsed-laser deposition is now a largely used growth method to prepare functional and multifunctional oxide films for application in microelectronics, spintronics, optics, materials for energy… The functional properties of such oxide films are strongly depending on the crystalline structure, and on the chemical composition through the local environment of cationic species surrounded by oxygen. While large oxygen deficiency cannot be obtained by classical growth method or in bulk state, oxide films with a high content of oxygen vacancies may be obtained by PLD. For oxide systems presenting possible stable sub-oxides, the formation of oxygen vacancies is linked to a decrease of the cationic valence state. A complete reduction can be observed leading to particular electronic properties: the case of TiOx (1.5<x<2) will be therefore presented and discussed. When no thermodynamically stable sub-oxides can be involved, the large oxygen deficiency may lead to the formation of nanocomposite films constituted by a metallic phase embedded in a stoichiometric oxide matrix. This phase separation induced by the control of oxygen pressure during the growth is in particular evidenced on Ga2Ox (2.1<x<3) films and their related physical (electrical and optical) properties are discussed.