Modulating the metal-insulator transition in VO2/Al2O3 (001) thin films by grain size and lattice strain

Sang, Jingxin; Zheng, Tan; Xu, Liang; Zhou, Xin; Tian, Shijian; Sun, Jiatong; Xu, Xiaofeng; Wang, Jianqiang; Zhao, Shuai; Liu, Yang

doi:10.1016/j.jallcom.2021.160208

Cited by 17 publications

(18 citation statements)

References 49 publications

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“…Experimentally, Sang et al . reported that the lattice strain was related to the electronic orbital occupancy in the rutile phase . The epitaxial VO 2 on the TiO 2 substrate could modify the occupied and unoccupied orbitals of the VO 2 thin films.…”

Section: Resultsmentioning

confidence: 99%

“…Bond Distances and Octahedral Volumes in Perfect (m + n)TiO reported that the lattice strain was related to the electronic orbital occupancy in the rutile phase. 47 The epitaxial VO 2 on the TiO 2 substrate could modify the occupied and unoccupied orbitals of the VO 2 thin films. Some results from TiO 2 /VO 2 interfaces can be extended to other systems, such as HfO 2 /VO 2 superlattices.…”

Section: Resultsmentioning

confidence: 99%

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Tuning the Metal–Insulator Transition in TiO₂/VO₂ Superlattices by Modifying the Layer Thickness or Inducing Defects

2022

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Vanadium dioxide (VO2) is a thermochromic material that can be used in advanced applications such as smart energy-saving windows and other smart optical/electronic devices. However, obtaining a comfortable metal–insulator transition temperature while improving solar utilization in VO2 remains an unresolved question at both the fundamental and application levels of research. Although studies on designing TiO2/VO2 multilayers to address the above issues have been widely reported, the nature of the metal–insulator transition and how thickness and defects affect phase transition behaviors are still subjects of ongoing debate. Herein, by varying the VO2 or TiO2 layer thicknesses or inducing defects such as oxygen vacancies and interstitial Ti/V atoms, the metal–insulator behavior including the atomic and electronic structures of TiO2/VO2 superlattices was systematically investigated. Our results show that the V–V distances in (m + n)TiO2/VO2(001) superlattices exhibit discontinuous dimerization characteristic and the superlattices exhibit alternating metal–insulator transition characteristics as the layer thickness m increases from 0 to 10. When 0 < m = n < 10, the band gaps for (m + n)TiO2/VO2(001) superlattices exhibit a downward-opening parabola. However, when 0 < m < 10 and m + n = 10, the band gaps fluctuate around 0.4 eV. Additionally, defects such as oxygen vacancies or cationic interstitial Ti/V atoms have a great impact on the metal–insulator transition in (m + n)TiO2/VO2(001) superlattices. Oxygen vacancies are preferentially located in the VO2 layer. When oxygen vacancies are present in the TiO2 layer, they migrate across the interface into the VO2 layers, indicating that there is considerable interdiffusion of V/Ti interstitial atoms across the interface. The interstitial V atoms diffuse more easily into the VO2 layer than interstitial Ti atoms. The current findings may be useful in understanding the metal–insulator behavior of VO2/TiO2 superlattices by varying the layer thickness or inducing defects, thereby providing a new approach for designing VO2-based heterostructures for smart energy-saving windows or other smart optical/electronic devices.

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Tuning the Metal–Insulator Transition in TiO₂/VO₂ Superlattices by Modifying the Layer Thickness or Inducing Defects

2022

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“…Previously, the T C of VO 2 is found to increase as grain size of VO 2 gets small. [ 30 ] In Figure 1b, the resistance ratio defined as R (30 °C)/ R (100 °C) was ≈210 for VO 2 /corning glass device, ≈770 for VO 2 /TiO 2 device, ≈300 for VO 2 /Al 2 O 3 device. R (30 °C) and R (100 °C) are the resistance of the device at 30 and 100 °C, respectively.…”

Section: Resultsmentioning

confidence: 99%

Effect of Thermal Conductivity of Substrate on the Giant Persistent Photoconductivity of Vanadium Dioxide Device

Lee

Mun

2022

Adv Elect Materials

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The substrate effect on giant persistent photoconductivity (GPPC) of VO2 devices fabricated on the substrates of corning glass, Al2O3(0001), and TiO2(001) is investigated. Under the applied voltage within the hysteresis loop of voltage–current curve of the VO2 device, the GPPC is achieved by a short single pulse laser at laser intensity of 8.9 × 106 W m−2. The minimum laser pulse width (Wmin) to trigger GPPC in VO2 devices is found to be as small as 80 µs in the VO2 device fabricated on corning glass substrate. The magnitudes of Wmin for GPPC increase in the order of corning glass, TiO2, and Al2O3 substrates. The variation of the Wmin on each substrate is understood as the dissimilarity of thermal conductivity of each substrate. The minimum time required to induce GPPC (the incubation time) is estimated using 1D thermal transport model, which shows good qualitative agreement with experimental results.

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“…Building upon the knowledge we acquired for developing spectrally selective photodetectors made of NPG that detect mid-IR light by means of the photothermoelectric effect ,, and the knowledge we acquired for developing thermal emitters based on NPG, we develop here the model of a mid-IR microbolometer that consists of a hexagonal boron nitride (h-BN) coated NPG, silicon nitride (Si 3 N 4 ), indium tin oxide (ITO), VO 2 on 90 nm h-BN, polymer, and gold (Au) mirror, as shown in Figure . Ultrathin films of VO 2 grown on h-BN or sapphire are strained. Although both heterostructures provide control over the phase transition temperature depending on the thickness of VO 2 , the advantage of h-BN is that it can be transferred onto target substrates.…”

Section: Introductionmentioning

confidence: 99%

Numerical Simulations of Nanolayered Heterostructures of Nanopatterned Graphene and Vanadium Oxide for Mid-Infrared Photodetectors Operating Close to Room Temperature

Shabbir

Chandra

2022

ACS Appl. Nano Mater.

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We present the model of an ultrasensitive mid-infrared (mid-IR) photodetector consisting of a hybrid heterostructure made of nanopatterned graphene (NPG) and vanadium dioxide (VO2) which exhibits a large responsivity of V/W, a detectivity exceeding D* ∼ 1010 Jones, and a sensitivity in terms of noise-equivalent power NEP ∼ 10 fW/ close to room temperature by taking advantage of the phase change of a thin VO2 film. Our proposed photodetector can reach an absorption of nearly 100% in monolayer graphene because of localized surface plasmons (LSPs) around the patterned circular holes. The geometry of the nanopattern and an electrostatic gate potential can be used to tune the absorption peak in the mid-IR regime between 3 and 12 μm. After the photon absorption by the LSPs in the NPG sheet, the phase change of VO2 from insulating to metallic phase is triggered, resulting in a current through the VO2 sheet due to the applied bias voltage V b. The response time is about 1 ms, shorter than the detection times of current VO2 bolometers. With use of a gradient thickness of the VO2 layer, a linear dependence between input power P inc of the incident light and the photocurrent I ph is achieved. Our envisioned mid-IR photodetector reaches detectivities of cryogenically cooled HgCdTe photodetectors and sensitivities larger than VO2 microbolometers while operating close to room temperature.

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Modulating the metal-insulator transition in VO2/Al2O3 (001) thin films by grain size and lattice strain

Cited by 17 publications

References 49 publications

Tuning the Metal–Insulator Transition in TiO₂/VO₂ Superlattices by Modifying the Layer Thickness or Inducing Defects

Tuning the Metal–Insulator Transition in TiO₂/VO₂ Superlattices by Modifying the Layer Thickness or Inducing Defects

Effect of Thermal Conductivity of Substrate on the Giant Persistent Photoconductivity of Vanadium Dioxide Device

Numerical Simulations of Nanolayered Heterostructures of Nanopatterned Graphene and Vanadium Oxide for Mid-Infrared Photodetectors Operating Close to Room Temperature

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Modulating the metal-insulator transition in VO2/Al2O3 (001) thin films by grain size and lattice strain

Cited by 17 publications

References 49 publications

Tuning the Metal–Insulator Transition in TiO2/VO2 Superlattices by Modifying the Layer Thickness or Inducing Defects

Tuning the Metal–Insulator Transition in TiO2/VO2 Superlattices by Modifying the Layer Thickness or Inducing Defects

Effect of Thermal Conductivity of Substrate on the Giant Persistent Photoconductivity of Vanadium Dioxide Device

Numerical Simulations of Nanolayered Heterostructures of Nanopatterned Graphene and Vanadium Oxide for Mid-Infrared Photodetectors Operating Close to Room Temperature

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Product

Resources

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Tuning the Metal–Insulator Transition in TiO₂/VO₂ Superlattices by Modifying the Layer Thickness or Inducing Defects

Tuning the Metal–Insulator Transition in TiO₂/VO₂ Superlattices by Modifying the Layer Thickness or Inducing Defects