Synthesis of vanadium dioxide thin films and nanoparticles

Abstract

Thin-film materials with ‘smart’ properties that react to temperature variations, electric or magneticfields, and/or pressure variations have recently attracted a great deal of attention. Vanadium dioxide(VO2) belongs to this family of ‘smart materials’ because it exhibits a semiconductor-to-metalfirst-order phase transition near 340 K, accompanied by an abrupt change in its resistivityand near-infrared transmission. It is also of great interest in condensed-matterphysics because it is a classic strongly correlated electron system. In order tointegrate vanadium dioxide into microelectronic circuits, thin-film growth ofVO2 has been studiedextensively, and studies of VO2 nanoparticles have shown that the phase transition is size-dependent. This paper presents a broadoverview of the growth techniques that have been used to produce thin films and nanoparticles ofVO2, including chemical vapor deposition, sol–gel synthesis, sputter deposition and pulsedlaser deposition. Representative deposition techniques are described, and typicalthin-film characteristics are presented, with an emphasis on recent results obtainedusing pulsed laser deposition. The opportunities for growing epitaxial films ofVO2, and fordoping VO2 films to alter their transition temperature and switching characteristics, are also discussed.