Search query: Pulsed Laser Deposition of VO2 Thin Films

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abstract: High quality vanadium dioxide (VO2) thin films have been successfully deposited by pulsed laser deposition without postannealing on (0001) and (1010) sapphire substrates. X ray diffraction reveals that the films are highly oriented with (010) planes parallel to the surface of the substrate. VO2 thin films on (0001) and (1010) substrates show semiconductor to metal transistions with electrical resistance changes as large as 4x104, 105, respectively. Thin films on (1010) substrate have a transition at as low as 55 degC with a hysteresis less than 1 degC. These transition properties are comparable with single crystal VO2.
author_names: Donghwan Kim

H S Kwok
title: Pulsed laser deposition of VO2 thin films
year: 1994

abstract: For growing high quality epitaxial VO2 thin films, the substrate with suitable lattice parameters is very important if considering the lattice matching. In addition, the thermal conductivity between the substrate and epitaxial film should be also considered. Interestingly, the c plane of hexagonal 6H SiC with high thermal conductivity has a similar lattice structure to the VO2 (010) which enables epitaxial growth of high quality VO2 films on 6H SiC substrates. In the current study, we deposited VO2 thin films directly on 6H SiC (0001) single crystal substrates by pulsed laser deposition (PLD) and systematically investigated the crystal structures and surface morphologies of the films as the function of growth temperature and film thickness. With optimized conditions, the obtained epitaxial VO2 film showed pure monoclinic phase structure and excellent phase transition properties. Across the phase transition from monoclinic structure (M1) to tetragonal rutile structure (R) the VO2/6H SiC (0001) film demonstrated a sharp resistance change up to five orders of magnitude and a narrow hysteresis width of only 3.3 degC.
author_names: Xiankun Cheng

Qiang Gao

Kaifeng Li

Zhongliang Liu

Qinzhuang Liu

Qiangchun Liu

Yongxing Zhang

Bing Li
title: Enhanced Phase Transition Properties of VO2 Thin Films on 6H SiC (0001) Substrate Prepared by Pulsed Laser Deposition
venue: Nanomaterials
year: 2019

author_names: Zeshan Adeel Umar

N Ahmed

Rizwan Ahmed

Muhammad Adnan Arshad

M Anwar-ul-Haq

Tousif Hussain

Maughal Ahmed Ali Baig
title: Substrate temperature effects on the structural, compositional, and electrical properties of VO2 thin films deposited by pulsed laser deposition
year: 2018

abstract: Microwave switching devices based on the semiconductor metal transition of VO2 thin films were developped on two types of substrates C plane sapphire and SiO2 Si, and in both shunt and series configurations. Under thermal activation, the switches achieved up to 30 40 dB average isolation of the radio frequency rf signal on 500 MHz 35 GHz frequency band with weak insertion losses. These VO2 based switches can be electrically activated with commutation times less than 100 ns, which make them promising candidates for realizing efficient and simple rf switches.
author_names: Frederic Dumas-Bouchiat

C Champeaux

A Catherinot

Aurelian Crunteanu

Pierre Blondy
title: rf microwave switches based on reversible semiconductor metal transition of VO2 thin films synthesized by pulsed laser deposition
year: 2007

abstract: Abstract Undoped and boron (B) doped VO2 thin films were successfully deposited by pulsed laser deposition. Boron doping enables to drastically reduce the metal insulator transition (MIT) temperature (TMIT) at a rate as large as 31.5 degC/at.%B. As boron doping is interstitial, B atoms can be incorporated in the VO2 matrix without affecting its stoichiometry as demonstrated by the invariability of the valence state of vanadium ions. Therefore, boron doping stands as an efficient strategy to reduce TMIT toward room temperature, while maintaining the contrast of both electrical resistivity and infrared transmittance across the MIT suitable for applications such as smart radiators.
author_names: Thameur Hajlaoui

Nicolas Emond

Christian Quirouette

Boris Le Drogoff

Joelle Margot

Mohamed Chaker
title: Metal insulator transition temperature of boron doped VO2 thin films grown by reactive pulsed laser deposition
year: 2020

abstract: Abstract Vanadium dioxide (VO2) because of its unique metal insulator phase transion around room temperature, has enormous potential for applications in thermochromic, electrochromic, microbolometery, and non volatile switches. However, obtaining phase pure VO2 has been challenging due to its narrow window of thermodynamic stability. Pulsed laser deposition (PLD) is considered to be one of the most promising technique to deposit phase pure VO2 thin films. While optimizing PLD processing parameters, (such as oxygen pressure (PO2) substrate temperature (Ts) laser energy (EL) target substrate distance (dT S) and laser repetition rate (RR) is crucial, and their effects have been reported, the effect of gas flow rate (QO2) has been largely neglected. Since the QO2 and PO2 of the PLD system are intertwined at the outset, most reports are focused only on either QO2 or PO2. We report on the effect of gas flow rate under constant PO2, on the quality of the VO2 thin films. Controlling flow rate affected the resistivity contrast between the metallic and insulator phases, the temperature ranges of the transition, and the width of hysteresis. We anticipate that this study will help set the standard for obtaining high quality VO2 thin films.
author_names: Syed Asad Manzoor Bukhari

Sooraj Kumar

Pawan Kumar

Sarang P Gumfekar

Hyun-Joong Chung

Thomas Thundat

Ankur Goswami
title: The effect of oxygen flow rate on metal insulator transition (MIT) characteristics of vanadium dioxide (VO2) thin films by pulsed laser deposition (PLD)
year: 2020

abstract: Abstract The influence of oxygen pressure on the structural and electrical properties of vanadium oxide thin films deposited on glass substrates by pulsed laser deposition, via a 5 nm thick ZnO buffer, was investigated. For the purposes of comparison, VO2 thin films were also deposited on c cut sapphire and glass substrates. During laser ablation of the V metal target, the oxygen pressure was varied between 1.33 and 6.67 Pa at 500 degC, and the interaction and reaction of the VO2 and the ZnO buffer were studied. X ray diffraction studies showed that the VO2 thin film deposited on a c axis oriented ZnO buffer layer under 1.33 Pa oxygen had (020) preferential orientation. However, VO2 thin films deposited under 5.33 and 6.67 Pa were randomly oriented and showed (011) peaks. Crystalline orientation controlled VO2 thin films were prepared without such expensive single crystal substrates as c cut sapphire. The metal insulator transition properties of the VO2/ZnO/glass samples were investigated in terms of electrical conductivity and infrared reflectance with varying temperatures, and the surface composition was investigated by X ray photoelectron spectroscopy.
author_names: Te-Wei Chiu

Kazuhiko Tonooka

Naoto Kikuchi
title: Influence of oxygen pressure on the structural, electrical and optical properties of VO2 thin films deposited on ZnO/glass substrates by pulsed laser deposition
year: 2010

abstract: There are significant challenges accompanied by fabricating a pure crystalline VO2 (M1) thin film with an abrupt metal to insulator phase change properties. Most fabrication methods yield an amorphous VO2 thin film that requires a post annealing process to be converted into crystalline VO2 (M1) Hence, the thickness of VO2 (M1) films produced is very limited. In this work, we report the growth of pure VO2 (M1) crystalline thin films onto a sapphire substrate in an oxygen atmosphere by the femtosecond pulsed laser deposition technique and using vanadium pentoxide (V2O5) as an ablation target. The thin films were deposited at substrate temperatures of 25 degC, 400 degC, and 600 degC, which reveal the crystallized structures of VO2 (M1) without post annealing. The thin film deposited at a substrate temperature of 600 degC exhibits a sharp and an abrupt metal to insulator transition (MIT) at a temperature of 66.0 2.5 degC with nearly four orders of magnitude of the resistivity change (3.5 decades) and a narrow MIT hysteresis width of 3.9 degC. Furthermore, the influence of the substrate temperature, nanoparticle or grain size, and film thickness on the MIT parameters such as sharpness of the transition temperature, hysteresis width, and amplitude are discussed for potential applications of tunable antennas, terahertz planar antennas, and RF microwave switches.
author_names: Eric Kumi-Barimah

Dimitris E Anagnostou

Gin Jose
title: Phase changeable vanadium dioxide (VO2) thin films grown from vanadium pentoxide (V2O5) using femtosecond pulsed laser deposition
year: 2020

abstract: The technique of pulse laser deposition with the separation of plume drops is used to produce VO2 thin films on sapphire(0001) and silicon(111) substrates. It is established that the energy density at the target and the oxygen pressure influence the structural and electrical properties of the films. All of the VO2 crystal films exhibit semiconductor metal transitions with a substantial change in the resistance (by 2 5 orders of magnitude) The transmittance in the range 200 800 nm and reflectance in the range 400 700 nm are studied in the temperature range from 20 to 100degC. The transmittance of the films at wavelengths from 300 to 800 nm shows a jump and hysteresis upon heating and cooling. It is for the first time established that the changes in the transmittance of the film are different in character at different wavelengths and the shape of the temperature hysteresis loop for optical transmittance in the visible and near ultraviolet regions does not in all areas replicate the shape of the hysteresis loop for the resistivity of the VO2 films. The difference in the behavior of the hysteresis curves for the transmittance and resistance is attributed to variations in the absorption of the films under variations in temperature.
author_names: Oleg Alexeyevic Novodvorsky

L S Parshina

Olga D Khramova

Vladimir Mikhalevsky

Kirill D Shcherbachev

Vladislav Ya Panchenko
title: Influence of the conditions of pulsed laser deposition on the structural, electrical, and optical properties of VO2 thin films
year: 2015

abstract: In this contribution, we demonstrate room temperature growth of highly oriented single phase nanocrystalline films of VO 2 (A) on glass substrates using pulsed laser deposition (PLD) technique under high oxygen pressure and small target substrate separation. The structural, morphological, optical, electrical and compositional properties of the deposited thin films have been studied by means of X ray diffraction, atomic force microscopy, spectrophotometry, 04 point probe method and X ray photoelectron spectroscopy, respectively. The plasma under which VO 2 (A) was grown has been analyzed by means of time and space resolved optical emission spectroscopy (OES) and Langmuir probe (LP) techniques. We evidenced a correlation between growth conditions and plasma characteristics. While OES showed that at the deposition distance corresponding to the length of the visible plasma, the plasma species are completely thermalized and characterized by a very low degree of excitation, the LP technique indicated a formation of charged clusters within the gas phase. By combining OES and LP data, a quadruple plasma structure has been shown. The growth of under stoichiometric (comparing to the parent V 2 O 5 target) nanocrystalline VO 2 (A) phase has been attributed to nanoparticle formation in the gas phase under a plasma environment rarefied in oxygen atoms due to the scattering and backscattering effects. This finding opens up the opportunity to grow VO 2 polymorphs at very low temperature by PLD for novel promising new device functionalities.
author_names: Slimane Lafane

S Malek

Jackie J Nel

Samira Abdelli-Messaci
title: Room temperature and high pressure pulsed laser deposition of nanocrystalline VO2 thin films on glass substrate: plasma and film analyses
year: 2021