Electrothermal actuation of vanadium dioxide for tunable capacitors and microwave filters with integrated microheaters

Vitale, Wolfgang A.; Petit, Luca; Moldovan, Camelia; Fernández-Bolaños, Montserrat; Paone, Antonio; Schüler, Andreas; Ionescu, Adrian M.

doi:10.1016/j.sna.2016.01.027

Cited by 36 publications

(31 citation statements)

References 13 publications

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“…Pure vanadium dioxide (VO 2 ) has two phases; below 340 K it has the monoclinic or M 1 phase with a band gap, whereas above 340 K it has the metallic rutile form, called the R phase [1][2][3]. The phase transition is fully reversible so that it is a promising material for various applications [4] such as smart windows [5], optical [6] or rf switches [7,8], and as a component of steep slope transistors [9][10][11]. Although the structural change at 340 K has been heavily studied, the electronic structures and especially the magnetic ground states of both R and M 1 phases are still debated [1,3,12].…”

Section: Introductionmentioning

confidence: 99%

Electronic structure of metallic and insulating phases of vanadium dioxide and its oxide alloys

Guo

Robertson

2019

Phys. Rev. Materials

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VO 2 attracts much attention due to its metal-insulator transition. Alloying VO 2 with MgO and GeO 2 allows the band gap and the transition temperature to be varied. We find that the spin order plays a key role in creating the band gap in the low-temperature M 1 phase. For MgO alloying, the alloying fraction n (Mg n V 1−n O 2−n) is varied from 12.5 to 33.3%. The minimum band gap does not change without a structural rearrangement because both band edges of insulating VO 2 consist of only V 3d states on sixfold-coordinated V sites. A crystal search finds that if the Mg fraction in the alloy is large enough (>20%), fivefold-coordinated V sites can have lower energy than the sixfold sites, and the band gaps are doubled. For GeO 2 alloying, the insulating M 1 structure reverts to rutile because GeO 2 has a rutile phase. The result matches the experimental observation and is very important in guiding VO 2 's applications such as smart coating and nonlinear resistor.

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Section: Introductionmentioning

confidence: 99%

Electronic structure of metallic and insulating phases of vanadium dioxide and its oxide alloys

Guo

Robertson

2019

Phys. Rev. Materials

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“…Most recently, 9 an order-of-magnitude breakdown of the Wiedemann-Franz law has been reported in metallic VO 2 in the vicinity of the semiconductor-to-metal transition. Moreover, VO 2 became a prominent candidate for ultrafast optical and electrical switches, 10,11 tunable capacitors, 12 microbolometers, 13 smart windows, 14,15 smart radiators in solar thermal 16 or space 17 applications, etc. For practical applications, various transition temperatures are desired and, through doping, the phase transition temperature can be tailored to fit a wide range of requirements.…”

Section: Introductionmentioning

confidence: 99%

“…22 However, shifting the SMT temperature in the other direction is less efficient and less studied. Introduction of smart thermochromic VO 2 based solar thermal collectors 16 and recent developments at the microelectronic device level 11,12 emphasize the importance of a reliable, inexpensive, and efficient doping that enables a precise control over a wide range of elevated T SMT in vanadium dioxide thin films. Studies on dopants shown to increase the transition temperature were mainly published for single crystal or powder VO 2 .…”

Section: Introductionmentioning

confidence: 99%

Elevated transition temperature in Ge doped VO2 thin films

Krammer

Magrez

Vitale

et al. 2017

Journal of Applied Physics

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“…Vanadium dioxide (VO 2 ) has been intensively studied due to its metal–insulator transition (MIT) at 340 K, between a high‐temperature metallic rutile phase and a low‐temperature insulating monoclinic phase . Potentially, VO 2 can be used as a thermochromic material in smart windows, in optical or radio frequency (RF) switches, and steep slope transistors . VO 2 is a strongly correlated material which makes it useful for optoelectronics .…”

Section: Introductionmentioning

confidence: 99%

Density Functional Theory Studies of the Metal–Insulator Transition in Vanadium Dioxide Alloys

Robertson

2019

Physica Status Solidi (b)

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Vanadium dioxide (VO2) is of great interest because it has a metal–insulator transition involving a change in structure and electronic structure. For certain applications, it is useful to vary the bandgap and the transition temperature. Although strain can be used, another method is to alloy VO2 with oxides such as GeO2 or MgO. Herein, density functional supercell calculations are carried out on these alloys. The bandgap of the alloys does not change because the band edges of the M1 phase consist of V 3d bands, where V is sixfold bonded. However, there is also a fivefold VO2/MgO structure with a much larger bandgap of up to 2.1 eV. For Ge alloying, the structure reverts to the rutile phase but with a bandgap, because GeO2 has a rutile phase. It is also found that hydrogen doping varies the oxide gap between 0 to 1 eV. The result is consistent with experimental observations and it gives an important view to explain the mechanism of alloying.

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Electrothermal actuation of vanadium dioxide for tunable capacitors and microwave filters with integrated microheaters

Cited by 36 publications

References 13 publications

Electronic structure of metallic and insulating phases of vanadium dioxide and its oxide alloys

Electronic structure of metallic and insulating phases of vanadium dioxide and its oxide alloys

Elevated transition temperature in Ge doped VO2 thin films

Density Functional Theory Studies of the Metal–Insulator Transition in Vanadium Dioxide Alloys

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