Future Trends in Microelectronics

2.4

On the Field-Induced Insulator–Metal Transition in VO₂ Films

Serge Luryi and Boris Spivak

Department of Electrical and Computer Engineering, Stony Brook University, Stony Brook, NY, 11794, USA

Department of Physics, University of Washington, Seattle, WA, 98195, USA

1 Introduction

First-order metal–insulator transitions (MITs) in crystalline materials have been known for many years¹ and correspond to a transformation between states with a dielectric (semiconductor) and a metallic types of conductivity. These transitions occur under the influence of certain external parameters, such as temperature and pressure, as well as with varying material composition. Materials exhibiting these phenomena include many transition metal oxides, of which over 40 are known to possess MITs.^{2 3}

Among the best-known MIT materials are vanadium oxides. Being able to combine with oxygen in 2-, 3-, 4-, and 5-valent states, vanadium forms a series of oxides of which at least eight exhibit MITs.⁴ Phase transition in V₂O₃ occurs at a critical temperature T_C = 150 K and in VO₂ at T_C = 340 K, with the electrical conductivity changing by up to 10 and 5 orders of magnitude, respectively. The MIT in vanadium oxides is also accompanied by a discontinuous variation of other than electrical properties, such as optical and magnetic. Vanadium dioxide, VO₂, is of particular interest for technology because its transition occurs near room temperature and furthermore its T_C is tunable over a wide range by doping ...