Vanadium–Al 2O 3 nanostructured thin films prepared by pulsed laser deposition: Optical switching

Abstract

The formation and optical response of VO x nanoparticles embedded in amorphous aluminium oxide (Al 2O 3) thin films by pulsed laser deposition is studied. The thin films have been grown by alternate laser ablation of V and Al 2O 3 targets, which has resulted in a multilayer structure with embedded nanoparticles. The V content has been varied by changing the number of pulses on the V target. It is found that VO x nanoparticles with dimensions around 5 nm have been formed. The structural analysis shows that the vanadium nanoparticles are oxidized, although probably there is not a unique oxide phase for each sample. The films show a different optical response depending on their vanadium content. Optical switching as a function of temperature has been observed for the two films with the highest vanadium content, at transition temperatures of about −20 °C and 315 °C thus suggesting the presence of nanoparticles with compositions V 4O 7 and V 2O 5, respectively.