Stress-Induced In Situ Modification of Transition Temperature in VO Films Capped by Chalcogenide.

We attempted to modify the monoclinic-rutile structural phase transition temperature () of a VO thin film in situ through stress caused by amorphous-crystalline phase change of a chalcogenide layer on it. VO films on C- or R-plane AlO substrates were capped by GeSbTe (GST) films by means of rf magnetron sputtering. of the VO layer was evaluated through temperature-controlled measurements of optical reflection intensity and electrical resistance. Crystallization of the GST capping layer was accompanied by a significant drop in of the VO layer underneath, either with or without a SiN diffusion barrier layer between the two. The shift of was by ~30 °C for a GST/VO bilayered sample with thicknesses of 200/30 nm, and was by ~6 °C for a GST/SiN/VO trilayered sample of 200/10/6 nm. The lowering of was most probably caused by the volume reduction in GST during the amorphous-crystalline phase change. The stress-induced in in situ modification of in VO films could pave the way for the application of nonvolatile changes of optical properties in optoelectronic devices.