Role of microstructures on the M1-M2 phase transition in epitaxial VO2 thin films

Ji, Yanda; Zhang, Yin; Gao, Min; Yuan, Zhen; Xia, Yudong; Chen, Jin; Tao, Bowan; Chen, Chonglin; Jia, Q. X.; Lin, Yuan

doi:10.1038/srep04854

Cited by 101 publications

(74 citation statements)

References 29 publications

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“…The average full width at half maximum (FWHM) of the peaks from the XRD ϕ -scans are 0.97°, 0.88°, 1.08° and 0.67° for the films on the reference, 1.0°, 2.75° and 5.0° vicinal substrates, respectively. The FWHM of the ϕ -scanning patterns can reflect the density of edge dislocations in the films31323334, which will be discussed later.…”

Section: Resultsmentioning

confidence: 99%

Surface step terrace tuned microstructures and dielectric properties of highly epitaxial CaCu3Ti4O12 thin films on vicinal LaAlO3 substrates

Yao

Gao

et al. 2016

Sci Rep

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Controllable interfacial strain can manipulate the physical properties of epitaxial films and help understand the physical nature of the correlation between the properties and the atomic microstructures. By using a proper design of vicinal single-crystal substrate, the interface strain in epitaxial thin films can be well controlled by adjusting the miscut angle via a surface-step-terrace matching growth mode. Here, we demonstrate that LaAlO3 (LAO) substrates with various miscut angles of 1.0°, 2.75°, and 5.0° were used to tune the dielectric properties of epitaxial CaCu3Ti4O12 (CCTO) thin films. A model of coexistent compressive and tensile strained domains is proposed to understand the epitaxial nature. Our findings on the self-tuning of the compressive and tensile strained domain ratio along the interface depending on the miscut angle and the stress relaxation mechanism under this growth mode will open a new avenue to achieve CCTO films with high dielectric constant and low dielectric loss, which is critical for the design and integration of advanced heterostructures for high performance capacitance device applications.

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Section: Resultsmentioning

confidence: 99%

Surface step terrace tuned microstructures and dielectric properties of highly epitaxial CaCu3Ti4O12 thin films on vicinal LaAlO3 substrates

Yao

Gao

et al. 2016

Sci Rep

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“…a few nm) one could observe different microscopic patterns and strain induced behaviors. For clarity we illustrate the lattice and unit cell structures of monoclinic M1, monoclinic M2 and rutile R phases in Fig. 3 [57,59,64,65]. In the M1 phase all V atoms pair and twist to form V-V dimers, while in the M2 phase half of the V atoms pair with the other half remaining unpaired [59].…”

Section: Samplesmentioning

confidence: 99%

Phase transition in bulk single crystals and thin films ofVO2by nanoscale infrared spectroscopy and imaging

et al. 2015

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We have systematically studied a variety of vanadium dioxide (VO 2 ) crystalline forms, including bulk single crystals and oriented thin films, using infrared (IR) near-field spectroscopic imaging techniques. By measuring the IR spectroscopic responses of electrons and phonons in VO 2 with sub-grain-size spatial resolution (~20 nm), we show that epitaxial strain in VO 2 thin films not only triggers spontaneous local phase separations but also leads to intermediate electronic and lattice states that are intrinsically different from those found in bulk. Generalized rules of strain and symmetry dependent mesoscopic phase inhomogeneity are also discussed. These results set the stage for a comprehensive understanding of complex energy landscapes that may not be readily determined by macroscopic approaches.

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“…14 Reports also suggest the formation of M2 phase under uniaxial strain. 15 This variation in resistivity during M1 −→ R transition, can be huge, upto 5 orders of magnitude, in the case of single crystals 16 with the transition temperature of 68 o C. However, polycrystalline thin films of VO 2 exhibit a change in resistivity of 4 orders of magnitude. 9 MIT in VO 2 can also be triggered by optical, 17 electrical, 18 mechanical means.…”

Section: Introductionmentioning

confidence: 99%

Effect of W addition on the electrical switching of VO2 thin films

Rajeswaran

Umarji

2016

AIP Advances

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Vanadium Oxide has been a frontrunner in the field of oxide electronics because of its metal-insulator transition (MIT). The interplay of different structures of VO2 has played a crucial role in deciding the magnitude of the first order MIT. Substitution doping has been found to introduce different polymorphs of VO2. Hence the role of substitution doping in stabilizing the competing phases of VO2 in the thin film form remains underexplored. Consequently there have been reports both discounting and approving such a stabilization of competing phases in VO2. It is reported in the literature that the bandwidth of the hysteresis and transition temperature of VO2 can be tuned by substitutional doping of VO2 with W. In this work, we have adopted a novel technique called, Ultrasonic Nebulized Spray Pyrolysis of Aqueous Combustion Mixture (UNSPACM) to deposit VO2 and W- doped VO2 as thin films. XRD and Raman spectroscopy were used to investigate the role of tungsten on the structure of VO2 thin films. Morphology of the thin films was found to be consisting of globular and porous nanoparticles of size ∼ 20nm. Transition temperature decreased with the addition of W. We found that for 2.0 at % W doping in VO2, the transition temperature has reduced from 68 o C to 25 o C. It is noted that W-doping in the process of reducing the transition temperature, alters the local structure and also increases room temperature carrier concentration.

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Role of microstructures on the M1-M2 phase transition in epitaxial VO2 thin films

Cited by 101 publications

References 29 publications

Surface step terrace tuned microstructures and dielectric properties of highly epitaxial CaCu3Ti4O12 thin films on vicinal LaAlO3 substrates

Surface step terrace tuned microstructures and dielectric properties of highly epitaxial CaCu3Ti4O12 thin films on vicinal LaAlO3 substrates

Phase transition in bulk single crystals and thin films ofVO2by nanoscale infrared spectroscopy and imaging

Effect of W addition on the electrical switching of VO2 thin films

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