Crystal Growth and Investigations on the Effects of Hydrogen Doping Vo 2
Vanadium Dioxide (VO2) has been studied extensively for its interesting electronic structure that allows it to go through Metal-Insulator Transition (MIT) at 65◦C. The nature of this phenomena is not entirely clear and more research is needed to firmly establish the science behind it and to realize possible applications; such as ultra-fast electrical and optical switching, sensor devices and Mott-Field Effect Transistors. One of the important experiments to understand the electronic structure of a material is Hall-effect measurements but due to acicular (needle like) nature of VO2 crystals, this subject is only studied either on millimeter sized samples which are not suitable for many device applications or on polycrystalline thin films that are under non-uniform stress due to the substrate adhesion which gives unsatisfactory results when performing experiments. This thesis introduces a new method for CVD growth of VO2 which is used in various applications such as Hall-effect experiments, two terminal devices and TEM studies. To control the growth process the interplay between oxygen and surface chemistry of sapphire, silica, Si and quartz substrates have been investigated. TEM analysis and electronic measurements on the effect of hydrogen doping in VO2 crystals are also reported.