Deposition-Temperature-Mediated Selective Phase Transition Mechanism of VO₂ Films

Abstract

A clear experimental explanation of the contribution of Mott and Peierls transitions to the insulator−metal transition (IMT) characteristics in vanadium dioxide (VO 2 ) is still lacking. Examining the crystal and electronic structures of epitaxial VO 2 films grown at various deposition temperatures, a Mott or a Peierls transition was observed. The VO 2 film deposited at 500 °C showed suppressed Peierls transition characteristics because of the large inplane compressive strain in the insulating phase. The VO 2 films deposited at 600 and 650 °C had a higher IMT temperature because of the relaxation of both the in-plane and out-of-plane strain, and there were abundant V 4+ states. Therefore, it was related to a collaborative Mott−Peierls transition. Finally, the VO 2 film deposited at 720 °C showed a suppressed Mott transition because of the abundance of V 3+ states in the insulating phase. Furthermore, an analysis of the electronic structure of the insulating and metallic phases using in situ X-ray photoelectron spectroscopy and X-ray absorption spectroscopy provide a complete band diagram to support the above explanation of the deposition-temperature-dependent IMT characteristics.

High quality VO2 thin films synthesized from V2O5 powder for sensitive near-infrared detection

“…4 c, with increasing temperatures, the two-terminal resistance gradually decreases, exhibiting the classical activated semiconductor behavior and switches to metallic behavior for temperature above 339 K. Upon cooling, the film displays a reverse jump to the insulating phase at temperature of 337 K, thus a very narrow hysteresis is exhibited. There is a dramatic change in resistance ( ) by over four orders of magnitude over the MIT, which shows comparable or better phase transition properties than that of VO 2 thin films synthesized by molecular beam epitaxy 34 and magnetron sputtering 8 , 12 , 35 . The inset of Fig.…”

“…Mott transition) 4 , 5 . The underlying physical picture of the MIT process has been studied by both theoretical and in situ experimental studies 6 – 8 . Moreover, the change in crystal structure is simultaneously accompanied by colossal changes in the electrical 8 – 10 , optical 11 – 14 , magnetic 15 , and thermal properties 16 , 17 .…”

“…The underlying physical picture of the MIT process has been studied by both theoretical and in situ experimental studies 6 – 8 . Moreover, the change in crystal structure is simultaneously accompanied by colossal changes in the electrical 8 – 10 , optical 11 – 14 , magnetic 15 , and thermal properties 16 , 17 . These properties make VO 2 promising in applications in smart windows 14 , 18 , 19 , optical modulators 20 , gas sensors 21 , memory devices 22 , photodetectors 23 and so forth 24 , 25 .…”

“…Different techniques such as chemical vapor deposition 10 , 21 , 23 , 26 , 27 , physical vapor deposition 15 , 28 , atomic layer deposition 29 , and hydrothermal method 9 , 11 , 30 – 32 has been used to synthesize VO 2 micro-and nanostructures including micro- and nanowires/beams/nets or nanoparticles. On the other hand, magnetron sputtering 8 , 12 – 14 , pulsed laser deposition 22 , 33 and molecular beam epitaxy 34 , are usually used to synthesize epitaxial films of VO 2 (constructed by the nanoparticles). Various factors that affect the MIT behavior of the resultant VO 2 have also been extensively investigated, including size 35 , morphology 2 , 12 , 13 , oxygen defect 22 , 36 , 37 , hydrogen 15 , and chemical doping 17 , 30 , 38 , etc.…”

Sensitive and Selective Electrochemical Resolution of Tyrosine with Ascorbic Acid through the Development of Electropolymerized Alizarin Sodium Sulfonate Modified Carbon Nanotube Paste Electrodes

“…Various techniques were reported for the examination of TR such as fluorimetry, gas chromatography‐mass spectrometry, liquid chromatography‐tandem mass spectrometry, chemiluminescence, spectrometric analysis, and capillary electrophoresis, but these methods were time consuming, tedious and costly as compare to electrochemical methods . The electrochemical methods mainly depends on modified sensors, recent works presented many modified sensors likely Europium hexacyanoferrate film, Boron‐doped diamond electrode, Nanostructures on gold electrodes, Carbon electrode modified with a Nafion/TiO2‐graphene composite film, Poly (thionine) glassy carbon electrode, Boron‐doped diamond and diamond nanowire electrode .…”