Synthesis and Electrical Behavior Of Vo2Thin Films Grown on Srruo3 Electrode Layers
Abstract
Owing to the fascinating metal-insulator transition, VO2 has attracted significant research interest in terms of material physics, synthesis, and device applications. Upon heating above ~340 K, VO2 undergoes an abrupt insulator-metal transition showing several orders of resistivity drop, as well as a change in the crystal structure. Electric-field induced metal-insulator transition of VO2 is of particular interest for its potential applications in emerging electronic device paradigms. Previous studies on planar-type VO2 devices fabricated on sapphire or similar insulating substrates revealed that an electric field on the order of 105 - 106 V/cm is required to trigger the electric-field induced metal-insulator transition. Therefore, a short gap between electrodes is essential to realize switching under low voltage bias. Growing VO2thin films on conductive layers is a promising approach that is expected to reduce the voltage required for switching in vertical devices and is of interest to cross-bar type memory and neuromorphic devices. In this study, VO2 films were grown on conducting oxide SrRuO3 layers. Apart from applications in magnetism, SrRuO3 is a widely studied template material to create multi-functional oxide heterostructures. Here, SrRuO3 buffered SrTiO3 (111) and Si/SiO2 were selected as platforms for VO2 growth. The properties of VO2 thin films grown on SrRuO3 buffer layers, as well as thermally and electric-field induced metal-insulator transition were systematically studied. Numerous growth experiments were conducted to identify the optimal growth conditions. Utilizing the current shunting associated with the conductive underlayer, electric-field induced metalinsulator transition was investigated in both the in-plane and out-of-plane configurations. A distributed resistance network with general applicability to understanding metal-insulator transitions is proposed to predict the electrical behavior of VO2grown on conducting layers.
Degree
M.Sc.
Advisors
Ramanathan, Purdue University.
Subject Area
Energy|Analytical chemistry|Chemistry|Condensed matter physics|Electromagnetics|Materials science|Optics|Physics
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