Oxide Electronics Utilizing Ultrafast Metal-Insulator Transitions

Abstract

Although phase transitions have long been a centerpiece of condensed matter materials science studies, a number of recent efforts focus on potentially exploiting the resulting functional property changes in novel electronics and photonics as well as understanding emergent phenomena. This is quite timely, given a grand challenge in twenty-first-century physical sciences is related to enabling continued advances in information processing and storage beyond conventional CMOS scaling. In this brief review, we discuss synthesis of strongly correlated oxides, mechanisms of metal-insulator transitions, and exploratory electron devices that are being studied. Particular emphasis is placed on vanadium dioxide, which undergoes a sharp metal-insulator transition near room temperature at ultrafast timescales. The article begins with an introduction to metal-insulator transition in oxides, followed by a brief discussion on the mechanisms leading to the phase transition. The role of materials synthesis in influencing functional properties is discussed briefly. Recent efforts on realizing novel devices such as field effect switches, optical detectors, nonlinear circuit components, and solid-state sensors are reviewed. The article concludes with a brief discussion on future research directions that may be worth consideration.

Speed limit of the insulator–metal transition in magnetite

“…After an initial 300 femtosecond destruction of individual trimerons, phase separation occurs on a 1.5 ± 0.2 picosecond timescale to yield residual insulating and metallic regions. This work establishes the speed limit for switching in future oxide electronics [10] Crossing the Verwey transition of magnetite (T V = 123 K) from above, charge fluctuations marking the conducting state freeze into an electronically ordered structure with octahedrally coordinated Fe 2+ and Fe 3+ sites, resulting in a hundred-fold increase in the resistivity [1]. This transition is accompanied by a change in the crystal symmetry from a high-temperature cubic inverse spinel to a monoclinic phase, the fine details of which have eluded crystallographers for decades.…”

Pressure–Temperature Phase Diagram of Vanadium Dioxide

“…[1][2][3] The electron correlation interplaying with lattice stabilizes a very rich phase diagram of VO2 that consists of many phases with distinct structures and electronic properties. Transitions between these phases can be driven by temperature, photo-excitation, hydrostatic pressure, uniaxial stress, or electrical gating.…”

Hydrogen Diffusion and Stabilization in Single-Crystal VO2 Micro/Nanobeams by Direct Atomic Hydrogenation

“…[5][6][7][8] In addition, this material has attracted much attention for its potential applications in ultrafast optical and electrical switching. [9][10][11][12][13] Therefore, much effort has been made to modulate the MIT by various approaches such as strain engineering, 14,15 ionic liquid gating, [16][17][18] electric field-induced oxygen vacancy, 19 and chemical doping. [20][21][22][23][24][25] In terms of chemical doping, using metal elements such as tungsten during growth can dramatically change the transition properties 20,26 , but it is an irreversible process.…”