scholarly journals Microfabrication of VO2 Thin Films via a Photosensitive Sol-Gel Method

Coatings ◽  
2021 ◽  
Vol 11 (10) ◽  
pp. 1264
Author(s):  
Chuanbao Wu ◽  
Yunwei Wang ◽  
Guangqiang Ma
Keyword(s):  
Thin Films ◽  
Low Cost ◽  
Anhydrous Methanol ◽  
Sol Gel ◽  
Nitrogen Atmosphere ◽  
Raw Material ◽  
Vanadyl Acetylacetonate ◽  
Storage Media ◽  
Microfabrication Technology ◽  
Vo2 Thin Films

VO2 films are widely used in photoelectric switches, smart glasses, storage media, and terahertz communications. In these applications, microfabrication technology is a very important process for producing microdevices or even improving film properties. In this paper, a novel photoetching microfabrication method is proposed for VO2 thin films. First, a VO2 precursor sol with ultraviolet photosensitivity was prepared using vanadyl acetylacetonate as the raw material and anhydrous methanol as the solvent. The dip-coated VO2 gel film can be directly subjected to photolithography processing without coating additional photoresist by using the photosensitive sol. A fine pattern on the VO2 film with good phase-transition performance can be obtained after annealing in a nitrogen atmosphere at 550 °C for 1 h. This method can be used to prepare grating, microarray, and various other fine patterns with the remarkable advantages of a low cost and simplified process, and the as-obtained material performances are unaffected using the method. It is a potential alternative method for optics, electronics, and magnetics devices based on VO2 thin films.

Sol-gel-derived gallium nitride thin films for ultraviolet photodetection

2019 ◽  
Vol 36 (1) ◽  
pp. 8-13 ◽  
Author(s):  
Chee Yong Fong ◽  
Sha Shiong Ng ◽  
NurFahana Mohd Amin ◽  
Fong Kwong Yam ◽  
Zainuriah Hassan
Keyword(s):  
Thin Films ◽  
Dark Current ◽  
Uv Light ◽  
Low Cost ◽  
Sol Gel ◽  
Contrast Ratio ◽  
Uv Photodetector ◽  
Content Type ◽  
Barrier Heights ◽  
Coating Method

Purpose This study aims to explore the applicability of the sol-gel-derived GaN thin films for UV photodetection. Design/methodology/approach GaN-based ultraviolet (UV) photodetector with Pt Schottky contacts was fabricated and its applicability was investigated. The current-voltage (I-V) characteristics of the GaN-based UV photodetector under the dark current and photocurrent were measured. Findings The ideality factors of GaN-based UV photodetector under dark current and photocurrent were 6.93 and 5.62, respectively. While the Schottky barrier heights (SBH) for GaN-based UV photodetector under dark current and photocurrent were 0.35 eV and 0.34 eV, respectively. The contrast ratio and responsivity of this UV photodetector measured at 5 V were found to be 1.36 and 1.68 μA/W, respectively. The photoresponse as a function of time was measured by switching the UV light on and off continuously at different forward biases of 1, 3 and 6 V. The results showed that the fabricated UV photodetector has reasonable stability and repeatability. Originality/value This work demonstrated that GaN-based UV photodetector can be fabricated by using the GaN thin film grown by low-cost and simple sol-gel spin coating method.

scholarly journals Enhanced visible transmittance and reduced transition temperature for VO2 thin films modulated by index-tunable SiO2 anti-reflection coatings

RSC Advances ◽  
2018 ◽  
Vol 8 (51) ◽  
pp. 28953-28959 ◽  
Author(s):  
Maodong Zhu ◽  
Hongji Qi ◽  
Bin Wang ◽  
Hu Wang ◽  
Dongping Zhang ◽  
...  
Keyword(s):  
Thin Films ◽  
Transition Temperature ◽  
Sol Gel ◽  
Dip Coating ◽  
Coating Technique ◽  
Infrared Transmittance ◽  
Visible Transmittance ◽  
P Index ◽  
Dip Coating Technique ◽  
Vo2 Thin Films

Index-tunable anti-reflection SiO2 coatings prepared on the surface of VO2 films by sol–gel dip-coating technique to enhance the visible and infrared transmittance of SiO2/VO2 films.

scholarly journals Effect of Solution Conditions on the Properties of Sol–Gel Derived Potassium Sodium Niobate Thin Films on Platinized Sapphire Substrates

Nanomaterials ◽  
2019 ◽  
Vol 9 (11) ◽  
pp. 1600 ◽  
Author(s):  
Alexander Tkach ◽  
André Santos ◽  
Sebastian Zlotnik ◽  
Ricardo Serrazina ◽  
Olena Okhay ◽  
...  
Keyword(s):  
Thin Films ◽  
Grain Size ◽  
Low Cost ◽  
Sol Gel ◽  
Precursor Solution ◽  
Dissipation Factor ◽  
Solution Concentration ◽  
Potassium Sodium Niobate ◽  
Sapphire Substrates ◽  
Average Grain Size

If piezoelectric micro-devices based on K0.5Na0.5NbO3 (KNN) thin films are to achieve commercialization, it is critical to optimize the films’ performance using low-cost scalable processing conditions. Here, sol–gel derived KNN thin films are deposited using 0.2 and 0.4 M precursor solutions with 5% solely potassium excess and 20% alkali (both potassium and sodium) excess on platinized sapphire substrates with reduced thermal expansion mismatch in relation to KNN. Being then rapid thermal annealed at 750 °C for 5 min, the films revealed an identical thickness of ~340 nm but different properties. An average grain size of ~100 nm and nearly stoichiometric KNN films are obtained when using 5% potassium excess solution, while 20% alkali excess solutions give the grain size of 500–600 nm and (Na + K)/Nb ratio of 1.07–1.08 in the prepared films. Moreover, the 5% potassium excess solution films have a perovskite structure without clear preferential orientation, whereas a (100) texture appears for 20% alkali excess solutions, being particularly strong for the 0.4 M solution concentration. As a result of the grain size and (100) texturing competition, the highest room-temperature dielectric permittivity and lowest dissipation factor measured in the parallel-plate-capacitor geometry were obtained for KNN films using 0.2 M precursor solutions with 20% alkali excess. These films were also shown to possess more quadratic-like and less coercive local piezoelectric loops, compared to those from 5% potassium excess solution. Furthermore, KNN films with large (100)-textured grains prepared from 0.4 M precursor solution with 20% alkali excess were found to possess superior local piezoresponse attributed to multiscale domain microstructures.

Thermal aging effect of vanadyl acetylacetonate precursor for deposition of VO2 thin films with thermochromic properties

2016 ◽  
Vol 82 ◽  
pp. 11-15 ◽  
Author(s):  
Jung-Hoon Yu ◽  
Sang-Hun Nam ◽  
Donguk Kim ◽  
Minha Kim ◽  
Hyeon Jin Seo ◽  
...  
Keyword(s):  
Thin Films ◽  
Thermal Aging ◽  
Aging Effect ◽  
Vanadyl Acetylacetonate ◽  
Thermochromic Properties ◽  
Vo2 Thin Films

Thermochromic VO2 Thin Film Prepared by Post Annealing Treatment of V2O5 Thin Film

2009 ◽  
Vol 79-82 ◽  
pp. 747-750 ◽  
Author(s):  
Dong Qing Liu ◽  
Wen Wei Zheng ◽  
Hai Feng Cheng ◽  
Hai Tao Liu
Keyword(s):  
Thin Film ◽  
Thin Films ◽  
Phase Transition ◽  
Photoelectron Spectroscopy ◽  
Sol Gel ◽  
Annealing Treatment ◽  
Simple Method ◽  
X Ray ◽  
Post Annealing ◽  
Vo2 Thin Films

Thermochromic vanadium dioxide (VO2) exhibits a semi-conducting to metallic phase transition at about 68°C, involving strong variations in electrical and optical properties. A simple method was proposed to prepare VO2 thin films from easily gained V2O5 thin films. The detailed thermodynamic calculation was done and the results show that V2O5 will decompose to VO2 when the post annealing temperature reaches 550°C at the atmospheric pressure of less than 0.06Pa. The initial V2O5 films were prepared by sol-gel method on fused-quartz substrates. Different post annealing conditions were studied. The derived VO2 thin film samples were characterized using X-ray diffraction and X-ray photoelectron spectroscopy. The electrical resistance and infrared emissivity of VO2 thin films under different temperatures were measured. The results show that the VO2 thin film derived from the V2O5 thin film annealed at 550°C for 10 hours is pure dioxide of vanadium without other valences. It was observed that the resistance of VO2 thin film with thickness about 600nm can change by 4 orders of magnitude and the 7.5-14μm emissivity can change by 0.6 during the phase transition.

Dielectric and I-V Characteristic of Lead Titanate Thin Films Prepared on ITO Glass Substrate

2015 ◽  
Vol 1109 ◽  
pp. 461-465 ◽  
Author(s):  
Nurbaya Zainal ◽  
Mohd Hafiz Wahid ◽  
Mohammad Rusop
Keyword(s):  
Thin Films ◽  
Lead Titanate ◽  
High Performance ◽  
Annealing Temperature ◽  
Low Cost ◽  
Ferroelectric Properties ◽  
Sol Gel ◽  
Soda Lime ◽  
Soda Lime Glass ◽  
Ito Glass

Performance of lead titanate, (PbTiO3) thin films have been successfully investigated on microstructural properties, I-V characteristic, dielectric properties, and ferroelectric properties. PbTiO3offers variety of application as transducer, ferroelectric random access memory, transistor, high performance capacitor, sensor, and many more due to its ferroelectric behavior. Preparation of the films are often discussed in order to improve the structural properties, like existence of grain boundaries, particle uniformity, presents of microcrack films, porosities, and many more. Yet, researchers still prepare PbTiO3thin films at high crystallization temperature, certainly above than 600 ̊C to obtain single crystal perovskite structure that would be the reason to gain high spontaneous polarization behavior. Although this will results to high dielectric constant value, the chances that leads to high leakage current is a major failure in device performance. Thus, preparation the thin films at low annealing temperature quite an essential study which is more preferable deposited on low-cost soda lime glass. The study focuses on low annealing temperature of PbTiO3thin films through sol-gel spin coating method and undergo for dielectric and I-V measurements.

scholarly journals A Low-Cost Mechatronic System for Sol-Gel Spraypyrolysis Technique

2020 ◽  
Author(s):  
Martin E. Oviedo ◽  
Fernando Alvira ◽  
Agustin Apaolaza ◽  
Juan F. Martiarena ◽  
Matías R. Tejerina
Keyword(s):  
Thin Films ◽  
Spray Pyrolysis ◽  
Low Cost ◽  
Sol Gel ◽  
Mechatronic System ◽  
Thermal Component ◽  
High Quality ◽  
Operation Conditions

This work presents a design of a low-cost spray pyrolysis automatized system which allows to manufacture high quality thin films. In particular, the thermal component of this instrument is modelled in different operation conditions, analyzed, and controlled. Also, different configurations for the whole instrument are analyzed.

scholarly journals Acetone-Sensitive Thin Films Comprising Coal Fly Ash Na-X Zeolites and Sol–Gel Nb2O5 Matrix

Nanomaterials ◽  
2021 ◽  
Vol 11 (9) ◽  
pp. 2399
Author(s):  
Katerina Lazarova ◽  
Silviya Boycheva ◽  
Marina Vasileva ◽  
Denitza Zgureva-Filipova ◽  
Biliana Georgieva ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Thin Films ◽  
Fly Ash ◽  
Coal Fly Ash ◽  
Sol Gel ◽  
Optical Quality ◽  
Film Deposition ◽  
Reflectance Spectra ◽  
Raw Material ◽  
X Zeolites

In this study, thin composite films of a sol–gel Nb2O5 matrix doped with coal fly ash Na-X zeolites were deposited by the spin-coating method. Fly ash of lignite coal collected from the electrostatic precipitators of one of the biggest TPPs in Bulgaria was used as a raw material for obtaining zeolites. Zeolite Na-X was synthesized by ultrasonic-assisted double stage fusion-hydrothermal alkaline conversion of coal fly ash. In order to improve the optical quality and sensing properties of the deposited thin films, synthesized zeolites were wet-milled for 60, 120, and 540 s prior to film deposition. The surface morphology of zeolite powders was studied both by scanning electron microscopy and transmission electron microscopy, while their porosity was investigated by N2-physisorption. Refractive index, extinction coefficient, and thickness of the films were determined through fitting of their reflectance spectra. The sensing ability of thin films towards acetone vapors was tested by measuring the reflectance spectra prior to and during exposure to the analyte, and the change in the reflection coefficient ∆R of the films was calculated. The influence of milling time of zeolites on the sensing and optical properties of the films was assumed and confirmed.

scholarly journals Morphological and Structural Properties of Sol-Gel Derived ZnO Thin Films Spin-Coated on Different Substrates

2020 ◽  
Vol 301 ◽  
pp. 35-42
Author(s):  
Nabihah Kasim ◽  
Zainuriah Hassan ◽  
Way Foong Lim ◽  
Sabah M. Mohammad ◽  
Hock Jin Quah
Keyword(s):  
Thin Film ◽  
Thin Films ◽  
High Resolution ◽  
Structural Properties ◽  
Low Cost ◽  
Zinc Acetate Dihydrate ◽  
Sol Gel ◽  
Precursor Solution ◽  
Xrd Analysis ◽  
Zno Thin Films

In this work, ZnO thin films were prepared by the low-cost sol-gel deposition method onto six different substrates (glass, ITO coated glass, sapphire (Al2O3), p-Si, p-GaN and polyethylene terephthalate (PET)) to study the effects of these substrates on the morphological and structural properties of the produced films. Precursor solution is Zinc acetate dihydrate based dissolved in ethanol with monoethanolamine (C2H7NO) added to act as a stabilizing agent to the sol. The corresponding ZnO thin films were characterized using field emission scanning electron microscopy (FESEM), high resolution X-ray diffraction (XRD) and atomic force microscopy (AFM). Results revealed distinct morphological and structural properties of ZnO thin films deposited on each substrate. The most uniform morphology was identified on glass, owing to the acquisition of the averagely stable grain sizes (58 nm – 61 nm) and thin film thicknesses (280 nm – 325 nm). High resolution XRD analysis showed that the films deposited on glass, ITO, p-Si, and p-GaN were attributed to hexagonal crystallite structures while the films deposited on sapphire and PET substrates exhibited amorphous phases. Amongst the samples, the ZnO thin film spin coated on p-Si demonstrated preferred orientation in (002) direction.

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