Projects Synthesis Materials Fabrication Devices Characterization Theory
This year we have nearly 30 projects covering a wide range of nanoscience, including facile synthesis of organic and inorganic nanowires and nanostructures, novel fabrication routes, building of functional bioarchitectures, nanostructured devices and nanowire applications. Please browse the menu (hover on a group and click on the project of choice) to view brief overviews of our projects.
Observation of metal insulator transition from an electron beam direct written VO2 nanostructures
Vanadium dioxide (VO2) is of great technical interest because of its applications in thermally activated optical switching devices, electrochromic and photochromic devices, thermal sensors and transparent electrical conductors. Such applications derive their origin from a insulator to metal phase transition at 670C as a result of slight but abrupt atomic rearrangement from monoclinic to a tetragonal phase. This phase transition is reversible, extremely fast (occurs in less than 500 femtoseconds), and is characterized by high spatial resolution and large changes in optical and electrical properties. Changes in resistivity of more than four orders of magnitude and large changes in optical properties in the visible and near infrared spectrum have been reported. Such behaviour makes this oxide a promising candidate for erasable optical storage devices, fast switching devices and energy conserving coating for windows and walls in buildings. Nanostructures of this material are expected to yield new properties resulting in novel optical behaviour. Electron beam lithography is an excellent method for defining small geometries in complex nano-devices. Direct electron beam writing using an electron beam-sensitive resist can be one of the solutions to solve these problems. Recently, alkoxide-based precursors have attracted great attention as electron beam resists for high resolution patterning. In order to reduce the size of VO2 structures in a controllable fashion and the ability to pattern them at desired locations with high precision, we have developed an electron beam-sensitive spin-coatable VO2 resist by stabilizing vanadium (V) triisopropoxide oxide, VO(OPri)3, with benzoylacetone, BzAc. This resist is capable of sub-10 nm resolution and on heat-treatment in a reducing atmosphere gives VO2 which shows insulator to metal transition.