Electrical Study of Device Arrays on Thin Film Vanadium Dioxide
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0966-T10-18
Electrical Study of Device Arrays on Thin Film Vanadium Dioxide R. G. Mani1,2, S. Ramanathan2, and V. Narayanamurti2 1 Department of Physics and Astronomy, Georgia State University, 29 Peachtree Center Avenue, Atlanta, GA, 30303 2 DEAS-Division of Engineering and Applied Sciences, Harvard University, 29 Oxford Street, Cambridge, MA, 02138
ABSTRACT Thin films of vanadium oxide (VO2) prepared by electron beam evaporation have been processed by photolithography into two-terminal strips with different length to width ratios for electrical measurements. Measurements on such specimens exhibit reproducibility across a chip, in addition to hysteretic transport, and a one-to-two orders of magnitude change in the resistance in the vicinity of the structural transition. In sum, these experiments show the feasibility of processing e-beam evaporated VO2 into small strip-like devices and maintaining concurrent material and electrical homogeneity over a number of electrical devices on the same chip. INTRODUCTION The VO2 phase of the transition-metal-oxide vanadium-oxide undergoes a structural monoclinic- to tetragonal- phase transition in the vicinity of 68 0C. This phase transition brings with it a change in the band structure and an insulator-to-metal transition which, in single crystals, includes orders-of-magnitude changes in the electrical resistance, and a large change in the infrared transmission.[1-5] The observed electronic-phase-transition in this strongly correlated material has been attributed both to the Peierls-type lattice distortion, and a Mott transition.[2,3,4,5] From a practical perspective, these large observed changes in the electrical and optical properties in the vicinity of room temperature have also created interest in applying this system as a smart material in novel switching applications.[6] This convergence of practical and scientific interest have served as the motivation for further investigations that aim to better understand the basic phenomena, and simultaneously improve the control over the electronic insulator-metal transition, independent of the structural transition. Studies thus far have shown that a large applied electrical bias[7,8] or intense photoexcitation[9,10,11,12] can trigger the electrical transition even below the structural transition temperature, and these studies have demonstrated a fast transition, ~ 102 fs, in thin films and small particles.[10,11,12] A fast electrically-induced or photo-induced change in the resistance suggests many applications. Thus, we study the characteristics of devices fabricated on thin films, which have thus far generally exhibited less dramatic changes than single crystals. Here, we report on the simultaneous electrical study of several small devices on a single chip processed by photolithography of e-beam evaporated thin VO2 films. The aim here has been to demonstrate- and obtain control over- device homogeneity in processed thin films.
EXPERIMENT AND RESULTS Thin films of VO2 were deposited by electron beam evaporation of VO2 pellet
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