(Invited) Towards the Realization of Bulk Dynamic Strain By Vertically Aligned VO2 Nanowire Hybrid Arrays

Monday, 2 October 2017: 11:50
Chesapeake E (Gaylord National Resort and Convention Center)
Y. Wang and J. Shi (Rensselaer Polytechnic Institute)
Significant epitaxial strain (~1%) is conventionally believed to exist only below the critical thickness limit at tens of nanometer scale, which greatly hinders the possible applications of strain engineering. The development of nanocomposite materials recently attempts to overcome the barrier by the inclusion of instantaneous phase separation between two materials during growth that ends up with a larger surface area, thus promoting large-scale strain. Here as a step forward, we report the growth of vertically aligned VO2 hybrid nanowire arrays that circumvents the pairing requirements for common nanocomposite and at the same time introduces the dynamic bulk strain by triggering the VO2 phase transformation. By controlling the growth temperature and oxygen vapor pressure, dense arrays of VO2 nanowires are obtained via a Chemical Vapor Deposition method. The ZnO/VO2 and BaTiO3/VO2 nanohybrid was then obtained by radio frequency sputtering. By varying the temperature to trigger the VO2 metal-insulator transition (MIT), we were able to dynamically strain the semiconductor overlayer. By studying both the single core-shell nanowire and the VO2 hybrid by photoluminescence and Raman spectroscopy, we show sound evidence of the dynamical strain from MIT. The utilization of phase transition from strongly correlated oxides thus provides a very promising approach for the realization of strain at bulk.