Authors: Gokul Gopalakrishnan Dmitry Ruzmetov Shriram Ramanathan
Publish Date: 2009/10/01
Volume: 44, Issue: 19, Pages: 5345-5353
Abstract
Vanadium dioxide VO2 has been shown to undergo an abrupt electronic phase transition near 70 °C from a semiconductor to a metal with an increase in dc conductivity of over three orders of magnitude making it an interesting candidate for advanced electronics as well as fundamental research in understanding correlated electron systems Recent experiments suggest that this transition can be manifested independent of a structural phase transition in the system and that it can be triggered by the application of an electric field across the VO2 thin film Several experiments that have studied this behavior however also involve a heating of the VO2 channel by leakage currents raising doubts about the underlying mechanism behind the transition To address the important question of thermal effects due to the applied field we report the results of electrothermal simulations on a number of experimentally realized device geometries showing the extent of heating caused by the leakage current in the “off” state of the VO2 device The simulations suggest that in a majority of the cases considered Joule heating is insufficient to trigger the transition by itself resulting in a typical temperature rise of less than 10 K However the heating following a fieldinduced transition often also induces the structural transition Nevertheless for certain devices we identify the possibility of maintaining the fieldinduced high conductivity phase without causing the structural phase transition an important requirement for the prospect of making highspeed switching devices based on VO2 thin film structures Such electronically driven transitions may also lead to novel device functionalities including ultrafast sensors or gated switches incorporating ferroelectricsThis work was supported by AFRLWPAFB and NSFSIA Supplement to the Nanoscale Science and Engineering Initiative under NSF Award Number PHY0601184 Device fabrication was performed in part at the Harvard University Center for Nanoscale Systems CNS a member of the National Nanotechnology Infrastructure Network NNIN which is supported by NSF Award No ECS0335765
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