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Interfacial crosslinked controlled thickness graphene oxide thin-films through dip-assisted layer-by-layer assembly means
摘要： The augmentation of research in graphene based thin films has been of great interest to various current industrial stakeholders. This is mainly due to the wide scope of films applications, ranging from nanoelectronics to separation membranes. Therefore, establishing a relation between graphene based thin film key characteristics and the fabrication operating conditions is of high significance. This study entails the successful fabrication of controlled-thickness crosslinked graphene oxide (GO) thin films on inexpensive silicon-based glass slide substrates. The method of film fabrication used is the dip-assisted layer-by-layer assembly, which has an added advantage of step-control of thin film thickness, good film uniformity and continuity. The thickness was primarily tuned through the use different sized crosslinkers; a covalent based sub-nanometer sized p-phenylenediamine and an electrostatic based polyethyleneimine on an interchangeable assembly with GO. Pre film fabrication, Fourier Transform Infra-Red and X-Ray Photoelectron Spectroscopy characterizations were carried out to determine the nature of interactions between GO and the crosslinkers. Post film fabrication, scanning electron microscopy, water contact angle measurements and profilometry analysis were undertaken for film continuity, hydrophilicity and thickness measurements respectively. A strong linear trend between film thickness of the differently crosslinked films and the number of bi-layers was established.
关键词： Graphene oxide,Thin film,Crosslinking,Thickness,Layer-by-layer
更新于2025-09-12 10:27:22
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Effects of ultraviolet photon irradiation and subsequent thermal treatments on solution-processed amorphous indium gallium zinc oxide thin films
摘要： Effects of exposure to ultraviolet (UV) photons and thermal treatments on solution-processed amorphous indium gallium zinc oxide (a-IGZO) films were investigated by X-ray photoelectron spectroscopy (XPS) and photoluminescence (PL) spectroscopy. As a result, oxygen vacancies obviously become more abundant in the films sintered at 250 or 300 ?C by the exposure to 7.21 eV photons and less abundant by the subsequent thermal treatment at 250 ?C in air. The drain current also clearly becomes smaller in a thin film transistor fabricated using the IGZO film in a manner opposite to the abundance of oxygen vacancies. That is, the drain current becomes smaller by the UV irradiation and returns to the original high value by the subsequent thermal treatment. This indicates that oxygen vacancies act as trapping centers or scattering centers of electrons. In addition, the reversible change of the drain current with the cycle of UV irradiation and the thermal treatment opens the possibility of the use of the IGZO films as a UV sensor.
关键词： oxygen vacancies,amorphous indium gallium zinc oxide,thin film transistor,UV irradiation,thermal treatment
更新于2025-09-10 09:29:36
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AACVD Grown WO3 Nanoneedles Decorated with Ag/Ag2O Nanoparticles for Oxygen Measurement in a Humid Environment
摘要： A sensitive material consisting of silver/silver oxide decorated WO3 was successfully grown in two steps via aerosol-assisted chemical vapour deposition (AACVD). Morphological, structural, and composition analysis revealed our method is effective for growing WO3 nanoneedles decorated with silver/silver oxide nanoparticles at relatively low temperature (≤ 375°C) onto sensor arrays printed on alumina substrate. The sensors were tested for oxygen under humid environment (relative humidity ~85%) with the concentration ranging between 0% and 20%. Gas sensing results showed good response to oxygen with optimum temperature was observed at 400°C for undecorated WO3 and at 350°C for silver/silver oxide decorated WO3. The addition of silver/silver oxide was found to improve the sensor response by almost 300%, making the sensor a potential alternative to replace existing Pb-based oxygen sensor.
关键词： Chemical sensor,heterojunction,tungsten oxide,oxygen detection,silver oxide,thin film sensor
更新于2025-09-09 09:28:46
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Studies on zinc oxide thin films by chemical spray pyrolysis technique
摘要： Zinc oxide (ZnO) thin films were deposited by chemical spray pyrolysis (CSP) technique using zinc acetate dihydrate solutions on microscopic glass substrates by varying the precursor concentration. The prepared films were characterized structurally and optically, using the powder X-ray diffraction (XRD) and UV analysis and Photoluminescence analysis. Crystallographic properties were analyzed through powder XRD. The XRD patterns shows a hexagonal structure with c-axis orientation (0 0 2) on self texturing phenomenon. Optical transmittance properties of the optimized ZnO thin films were investigated by using UV-Vis spectroscopy. The optical studies predicated a maximum transmittance in the range of above 70% with direct band gap values in the range of 2.9 to 3.2eV for the zinc oxide thin films. Under excitation of 300 nm radiations, sharp deep level emission peak at 2.506 eV dominates the photoluminescence spectra with weak deep level and near band edge emission peak at 3.026 and 3.427 eV respectively.
关键词： Photoluminescence,Transparent conducting oxide (TCO),UV-Vis,Zinc Oxide thin film,CSP technique,X-ray diffraction (XRD)
更新于2025-09-09 09:28:46
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A New High-Gain Operational Amplifier Using Transconductance-Enhancement Topology Integrated with Metal Oxide TFTs
摘要： This paper presents an integrated operational amplifier (OPAMP) consisting of only n-type metal oxide thin-film transistors (TFTs). In addition to using positive feedback in the input differential pair, a transconductance-enhancement topology is applied to improve the gain of the OPAMP. The OPAMP has a voltage gain (Av) of 29.54 dB over a 3 dB bandwidth (BW) of 9.33 kHz at a supply voltage of 15 V. The unity-gain frequency, phase margin and DC power consumption (PDC) are 180.2 kHz, 21.5°PM and 5.07 mW, respectively.
关键词： transconductance-enhancement topology,Operational amplifier,positive feedback,metal oxide thin-film transistors (TFTs)
更新于2025-09-09 09:28:46
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Extraction of Contact Resistance and DC Modelling in Metal Oxide TFTs
摘要： Based on the device physics, a simple and fast method of extracting contact resistance in metal oxide thin-film transistors (MOTFTs) is proposed through the I-V characteristics. This method divides the channel into two parts: the contact channel and the intrinsic channel, and assumes the electrons injected into the active layer at the source side are completed in the line injection. Using the I-V characteristics, the contact voltage can be obtained, and then the contact resistance can be extracted. The results indicate that contact resistance in MOTFTs depends on Vg, Vd, and L. Applying the extraction results, a DC drain current model considering contact resistance is proposed. Using this model, we can accurately describe the measurements of MOTFTs with channel lengths scaling from 50 μm to 10 μm. Through the extensive comparisons between the model results and the measurements, the validity of the method is strongly supported. This extraction method uses non-numerical iteration, which is simple, fast and accurate.
关键词： contact voltage,Metal oxide thin-film transistors,contact resistance,I-V characteristics.,DC model
更新于2025-09-09 09:28:46
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The Effect of the Thickness and Oxygen Ratio Control of Radio-Frequency Magnetron Sputtering on MgZnO Thin-Film Transistors
摘要： In this study, we use silicon dioxide for a magnesium-zinc-oxide thin-film transistor gate dielectric layer, controlling the thickness of the active layer and the Mg content of the film by radio-frequency (RF) sputtering. With an ideal thickness, a magnesium-zinc-oxide thin-film transistor can function normally. As the active layer thickness is controlled at 10 nm and the sputtering oxygen-flow rate is controlled at 14% to properly compensate for the oxygen vacancies, we can obtain the best features. The result of the analysis showed a field-effect mobility of 5.65 cm2/V · s, a threshold voltage of 3.1 V, a subthreshold swing improved to 0.80, and a current-switch ratio of over five orders of magnitude.
关键词： RF Sputtering,Magnesium Zinc Oxide,Thin-Film Transistor
更新于2025-09-09 09:28:46
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Electrical Conductivity of Reduced Graphene Oxide Thin-Film Layers
摘要： This work deals with the research of the electric properties of thin film layer of reduced graphene oxide. A structure of graphene oxide (GO) is represented by randomly distributed on a surface of substrate small islets of graphene with sp2 hybridized bonds surrounded by wide areas with sp3 bonds functionalized by oxygen groups. When electrons are confined in two-dimensional materials, quantum-mechanically enhanced transport phenomena such as the quantum Hall effect can be observed. Reduced graphene oxide, consisting of an isolated single atomic layer of graphite, is an ideal realization of such a two-dimensional system, therefore the partly semiconductive properties could be observed.
关键词： electrical conductivity,quantum Hall effect,reduced graphene oxide,thin-film layers,sp2 hybridized bonds
更新于2025-09-04 15:30:14
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Effects of doping by aluminum or lanthanum on the electrical and electroluminescence properties of Ca0.6Sr0.4TiO3:Pr thin films
摘要： Thin-film electroluminescent devices containing Ca0.6Sr0.4TiO3:Pr, Al-doped Ca0.6Sr0.4TiO3:Pr, or La-doped Ca0.6Sr0.4TiO3:Pr phosphors were prepared by a conventional sol–gel and firing method. Doping by Al improved the performance of the device markedly, in that its current-starting voltage and emission-starting voltage decreased, its luminance response became more rapid, and its relative quantum efficiency increased. Almost all the effects of doping with La were opposite to those of doping with Al. On stacking thin films of Al-doped Ca0.6Sr0.4TiO3:Pr and La-doped Ca0.6Sr0.4TiO3:Pr, the current-starting voltage and the emission-starting voltages decreased further and the relative quantum efficiency increased further in comparison with the Al-doped film. The effects of doping by Al and La can be understood by assuming that Ca0.6Sr0.4TiO3:Pr separates into n-type and p-type semiconducting regions as a result of the electromigration of oxygen vacancies, and that the oxygen-vacancy density increases or decreases on doping by Al and La, respectively.
关键词： Perovskite titanate,Praseodymium,Lanthanum,Oxide thin film,Aluminum,Electroluminescence
更新于2025-09-04 15:30:14
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Growth and Structural Properties of Graphene Oxide Thin Film with Spray Pyrolysis Technique
摘要： The spray pyrolysis technique (SPT) is one of the most useful and simple methods to grow graphene oxide (GO) thin film. Good-quality GO thin films were fabricated by spray coating with GO powder (prepared by the modified Hummers method) on glass substrates. Raman spectroscopy, Field Emission Scanning Electron Microscope (FESEM), X-ray diffraction (XRD) analysis, and UV–visible spectroscopy were done to observe the presence of functional groups in the growth thin films and to determine the structure of GO. From the result of XRD test, the GO demonstrates peak at 10.58°(2θ), while the Raman spectroscopy reveals the presence of two prominent peaks, known as D and G bands, as well as 2D band. The ID/IG ratio for spray-deposited GO film was calculated with the value of 0.84. FESEM images showed that the glass substrates were completely covered by GO at different magnifications with a sheet-like structure. The optical absorption of graphene oxide was also observed at a wavelength rang of 275-350 nm.
关键词： Graphene Oxide,Thin Film,Spray Pyrolysis Technique,Structural Properties
更新于2025-09-04 15:30:14