Optically Monitored Electric-Field-Induced Phase Transition in Vanadium Dioxide Crystal Film

Abstract

Vanadium dioxide (VO2), due to its electrically induced metal-to-insulator transition with dramatic changes in electrical and optical properties, is considered to be a powerful material for electro-optical devices. However, there are still some controversies about phase transition mechanism under voltage. Here, based on optical characterizations on VO2 crystal nanofilm during the whole process of phase transition, temporal evolution and spatial distribution of changes in electricity, optic and temperature are investigated simultaneously, to explore the mechanism. The variations of Raman spectrum and reflected spectrum, and changes in current and temperature are evidences for occurrence of phase transition, which exhibit different changing behaviors with time and space. These results offer a better understanding of the phase transition mechanism, implying that lattice structure of VO2 changes gradually after applying voltage until the structure is completely converted to metallic structure, which causes a rapid increase in carrier density, resulting in a rapid change in current, reflected spectrum and temperature. Temperature rise before phase transition and applied electric field alone are not enough for triggering metal-insulator transition, but these two factors can act synergistically on structural transformation to induce phase transition.

An Interesting Functional Phase Change Material VO2: Response to Multivariate Control and Extensive Applications in Optics and Electronics

“…With the study of microscopic processes and advances in detection techniques, multiple E‐MIT mechanisms have been reported. [ 5b,21,64,72,75 ] The following paper mainly discusses the regulatory mechanism of VO 2 ‐based devices from the Joule heating, electric field mechanism and electrochemical mechanism.…”

“…In Table 1, the phase transition mechanism involved in the research of VO 2 ‐based devices in recent years is summarized. In recent years, the application of VO 2 material field‐induced phase transition involves a diversified mechanism, the most common of which is the combination of electric field mechanism and Joule heating mechanism, some studies use electric field to trigger phase transition, Joule heat to maintain the metal phase, [ 72 ] or use electric field to maintain VO 2 phase in the hysteresis region, with Joule heating to induce two‐phase transition. [ 9 ] In addition, the fusion of hydrogen doping and oxygen vacancies in electrochemical mechanisms has also been reported in recent years.…”

VO2 Thin Film Enabled Free Space Modulation of Infrared Light Using Pulsed Electric Field

“…35,41 In order to trigger the semiconductor-to-metal transition (SMT) with electric field only, past reports mentioned large voltage requirements to cause a noticeable transition. 44,45 In this work, we have synthesized a good quality VO 2 film on a small circular area of the GaN substrate and the oxidized silicon-on-insulator (SOI) substrate, using a modified synthesis method, 35,41 and have used interdigitated metal finger patterns on the VO 2 film layers to apply required electric field. The film quality and device geometry resulted in a fast phase transition via localized heating of the membrane, allowing for more than 50% intensity modulation at 2600 nm IR wavelength with frequencies exceeding 10 kHz.…”

“…In previous work, we demonstrated near-IR modulation using the VO 2 film on the GaN substrate for 790 and 1550 nm IR beam, which resulted in optical modulation of 7 and 14%, respectively, for up to 300 μs pulses. However, the IR modulation was demonstrated with the application of external heating to the VO 2 film to vary the temperature of the film and initiate phase transition and significant optical modulation. , In order to trigger the semiconductor-to-metal transition (SMT) with electric field only, past reports mentioned large voltage requirements to cause a noticeable transition. , In this work, we have synthesized a good quality VO 2 film on a small circular area of the GaN substrate and the oxidized silicon-on-insulator (SOI) substrate, using a modified synthesis method, , and have used interdigitated metal finger patterns on the VO 2 film layers to apply required electric field. The film quality and device geometry resulted in a fast phase transition via localized heating of the membrane, allowing for more than 50% intensity modulation at 2600 nm IR wavelength with frequencies exceeding 10 kHz.…”

A Microwave Field-Induced Nonlinear Metamaterial with Wafer Integration Level

“…Some nonlinear materials have been reported in which the material itself, such as graphene, − vanadium dioxide, , etc., can change electromagnetic propagation parameters under the action of electromagnetic fields, so as to control the electromagnetic wave transmission. It has been proved that those materials have great application potential in the field of electromagnetic manipulation, but their properties in microwave band have not been made fully usable due to problems of difficult processing and insufficient electromagnetic manipulation ability.…”