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Toward reproducible metal-insulator transition characteristics in V <sub/>2</sub> O <sub/>3</sub> thin films sputter-deposited on glass
摘要： Vanadium sesquioxide (V2O3) exhibits remarkable property changes through its metal-insulator transition near 150 K and is a very promising candidate for device applications. Thin V2O3 films were deposited on SiO2 glass by reactive DC magnetron sputtering. While resistivity changes over four orders of magnitude were demonstrated, films deposited under nominally identical conditions exhibited significant differences in electrical characteristics, which would hinder reproducibility under deposition techniques appropriate for industrial scale production with standard control features. These differences were attributed to small deviations from exact stoichiometry. A post-deposition thermal treatment consistent with equilibrium temperature and oxygen pressure conditions for V2O3 applied to the samples succeeded in nearly equalizing their characteristics within a relatively short time and without negatively impacting the glass substrate or film continuity. Analysis of film structure, morphology, and resistivity measured from room temperature through the metal-insulator transitions, both before and after the thermal process, revealed information about the interplay between non-stoichiometry, residual stress, and electrical characteristics of the films. The approach employed can lead to reproducible results for V2O3 films and is applicable to similar materials which exhibit metal-insulator transitions.
关键词： stoichiometry,sputtering,thin films,V2O3,thermal treatment,metal-insulator transition
更新于2025-09-09 09:28:46
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Photo and thermally induced properties change in Bi/Ag/Se trilayer thin film
摘要： In this article, we have demonstrated the optical and structural properties change in Bi/Ag/Se trilayer thin films by the influence of thermal and photon energy. The trilayer films prepared by thermal evaporation technique were annealed and laser irradiated at room temperature. The X-ray diffraction study revealed the Ag2Se phase formation and the surface morphology change is being studied by Field emission scanning electron microscopy. The optical properties of the studied films were characterized by using FTIR spectrophotometer in the wavelength range 400–1200 nm. The reduction of optical band gap by both thermal and laser irradiation is being discussed on the basis of chemical disorderness, defect states and density of localized states in the mobility gap. The Raman shift due to annealing and irradiation supports the changes in the film. The large change in optical band gap in thermal annealing is useful for memory device and waveguide fabrication.
关键词： optical properties,annealing,band gap,laser irradiation,Trilayer thin films
更新于2025-09-09 09:28:46
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Reference Module in Chemistry, Molecular Sciences and Chemical Engineering || Organic–Organic Heterostructures
摘要： Thin films of organic molecules are now of technological importance as the active component in modern electronic and optoelectronic devices, such as organic light-emitting devices, organic thin-film transistors, organic sensors, and organic photovoltaic devices. After a first era of general excitement, it was soon discovered that to be able to rival their inorganic counterparts, one has to control the structure, crystallinity, and morphology during thin-film growth and understand and control their molecular electronic properties. An important topic therein is the formation of interfaces, specifically the organic-metal interface, which acts as the contact. Consequently, the growth and the electronic level alignment (band alignment) of organic molecules on metal surfaces have been extensively studied for the last 20 years. However, organic devices in general comprise more than one organic layer. As a consequence, we also have to consider organic–organic interfaces and the electronic level alignment across them and how heteroorganic films form. In comparison with the huge number of publications dealing with organic film growth on metal, the literature of controlled surface science studies of organic film growth on an organic layer is rather scarce. And indeed, there are a number of challenges one has to be aware of, when investigating organic heterostructure formation. In contrast to metal single-crystal substrates, which are available in every orientation, organic single crystals, large enough to handle with surface science methods, are hardly available, let alone in various orientations. The best approximation to a single crystal is organic thin films composed of crystallites of the same orientation that tile the substrate surface. By careful selection of the inorganic substrate and growth conditions, a number of orientations can be achieved. A second difficulty is that many surface science methods use electrons and thus can be prone to charging and beam damage particular for thick films.
关键词： electronic devices,optoelectronic devices,thin films,organic-metal interface,Organic–organic heterostructures,molecular electronic properties
更新于2025-09-09 09:28:46
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Annealing Temperature Dependent Structural and Optical Properties of RF Sputtered ZnO Thin Films
摘要： This work investigates the effect of annealing temperature on structural and optical properties of ZnO thin films grown over Si (100) and glass substrates using RF sputtering technique. Annealing temperature has been varied from 300 °C to 600 °C in steps of 100, and different microstructural parameters such as grain size, dislocation density, lattice constant, stress and strain have been evaluated. The structural and surface morphological characterization has been done using X-ray Diffraction (XRD) and Scanning Electron Microscope (SEM). XRD analysis reveals that the peak intensity of (002) crystallographic orientation increases with increased annealing temperature. Optical characterization of deposited films have been done using UV-Vis-NIR spectroscopy and photoluminescence spectrometer. An increase in optical bandgap of deposited ZnO thin films with increasing annealing temperature has been observed. The average optical transmittance was found to be more than 85% for all deposited films. Photoluminiscense spectra (PL) suggest that the crystalline quality of deposited film has increased at higher annealing temperature.
关键词： ZnO,Annealing Temperature,Thin Films,Optical Properties,RF Sputtering,Structural Properties
更新于2025-09-09 09:28:46
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Selenization of (Cu, In, Ga)/Se/Mo/Glass Thin Films: A Real-Time Synchrotron X-ray Scattering Study
摘要： The precursor selenization of (Cu, In, Ga)/Se/Mo/glass thin films during annealing without additional supply of Se was studied through a real-time synchrotron X-ray scattering experiment. At a lower temperature, the crystalline CIS, Cu2In, In2Se3, and Ga2Se3 phases were formed. By increasing the temperature, some parts of the crystalline CIS phase decomposed into Cu2In and In2Se3 phases. At a higher temperature, the crystalline CIGS phase was synthesized gradually by the reaction of the crystalline Cu2In, In2Se3, and Ga2Se3 phases, and not by direct crystallization of the amorphous precursor. The behavior of the integrated intensities and the crystal domain sizes were consistent with the changes in X-ray powder diffraction profiles. The high synthesis temperature in the CIGS phase was attributed to the high activation energy barrier for diffusion of Ga ions in the crystalline Ga2Se3 phase.
关键词： Real-Time Synchrotron X-ray Scattering,Synthesis of the CIGS Phase,Selenization During Annealing,(Cu, In, Ga)/Se/Mo/Glass Thin Films
更新于2025-09-09 09:28:46
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Study of Annealing Influence on Basic Properties of Indium Tin Oxide Nanorod Films Deposited Using Glancing Angle Ion-Assisted Electron Beam Evaporation
摘要： Indium tin oxide (ITO) nanorod ?lms were deposited onto glass slides and Si wafers using ion-assisted electron beam evaporation with a glancing angle deposition technique. The annealing in?uence on the basic properties of the as-deposited ITO nanorod ?lms was studied in the range of 100–500 °C for two hours in air. The crystallinity of the ITO nanorod ?lms was enhanced with the increasing annealing temperature, and the average transmission of the as-deposited ITO nanorod ?lms in the visible range was 90%. This value did not change signi?cantly after the annealing process. The optical bandgap of the as-deposited ITO nanorod ?lms was 3.94 eV and increased slightly after annealing. The sheet resistance of the as-deposited ITO nanorod ?lms was 12.9 Ω/□ and increased to 57.8 Ω/□ at an annealing temperature of 500 °C. The as-deposited ITO nanorod ?lms showed nanorod structures with average diameters of 79 nm, which changed slightly with the annealing temperature. The root mean square roughness of the as-deposited ITO nanorod ?lms was 7.9 nm and changed slightly with annealing. The as-deposited ITO nanorod ?lms had an average contact angle of 110.9°, which decreased to 64.2° at an annealing temperature of 500 °C. The experimental results showed that varying the annealing temperature in?uenced the structural, electrical and wettability properties of the ITO nanorod ?lms while the optical properties and surface morphology were almost unaffected.
关键词： Physical Properties,Annealing Temperature,Glancing-Angle Ion-Assisted Electron-Beam Evaporation,ITO Nanorod Films
更新于2025-09-09 09:28:46
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Diode Parameters of Heterojunctions Comprising <i>p</i> -Type Ultrananocrystalline Diamond Films and <i>n</i> -Type Si Substrates
摘要： In the current research, heterojunctions comprising p-type ultrananocrystalline diamond/hydrogenated amorphous carbon composite (UNCD/a-C:H) films and n-type Si substrates were formed via pulsed laser deposition. To extract their junction parameters via thermionic emission (TE) theory and Norde model, the measurement of dark current density–voltage curves was carried out under various temperatures ranging from 300 to 60 K. Through TE theory, the ideality factor values at 300 K and 60 K were 2.70 and 8.66, respectively. This justified that a heavy recombination process occurs at the junction interface in addition to another tunneling process at 300 K. The tunneling process is predominant at low temperatures. The barrier height values were 0.78 eV and 0.18 eV at 300 K and 60 K, respectively. The values for series resistance (Rs) at 300 K and 60 K were 275.24 Ω and 78.66 kΩ, respectively. The increment of Rs at low temperatures was likely due to the decrease of carrier concentration in the B-doped UNCD/a-C:H films when temperature was decreased.
关键词： PLD,Thin Films,UNCD/a-C:H,Heterojunction,Junction Parameters
更新于2025-09-09 09:28:46
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Hybrid and pristine polyalkylthiophene Langmuir-Schaefer films: Relationships of electrical impedance spectroscopy measurements, barrier properties and polymer nanostructure
摘要： Molecular organization in solid state plays a central role on organic devices performance. In this sense, a thorough investigation of thin films with application in organic electronics is imperative. This work addressed the fabrication and the morphological, optical and electrical characterization of Langmuir-Schaefer (LS) films of poly(3-hexylthiophene) (P3HT), pristine and mixed with stearic acid (SA), and their use as the active layer in organic Schottky diodes. The floating materials isotherms showed the SA molecules acting as a stabilizer for the P3HT in the Langmuir trough. Moreover, deposited P3HT:SA films present significant morphological changes, an improvement of the films overall structural ordering and a more effective charge transport within the active layer through electrical outcome. The alternating current measurements along with theoretical fitting, using equivalent electrical circuits, provided a good alternative to investigate the interfacial effects of the P3HT and P3HT:SA films deposited onto Al and Au electrodes.
关键词： Electrical impedance spectroscopy,Structure-property relations,Polythiophene,Langmuir-Schaefer,Thin films
更新于2025-09-09 09:28:46
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Influence of 120 MeV S9+ ion irradiation on structural, optical and morphological properties of zirconium oxide thin films deposited by RF sputtering
摘要： The calibrated and controlled swift heavy ions (SHI) beam irradiation generates defects which can cause modifications in various properties of the materials such as structural, optical, magnetic, morphological, and chemical etc. The passage of ion through the target material causes the nuclear energy losses (Sn) and electronic energy losses (Se). The Se dominates over Sn in SHI irradiation. In the present study, ZrO2 thin films were grown on silicon and glass substrate by using RF sputtering deposition technique. For the purpose of modifications induced by swift heavy ions, these films were irradiated by a 120 MeV S9+ ion beam of 1 pnA current, with varying ion fluences from 5E12 to 1E13 ions/cm2, using the tandem accelerator at the Inter University Accelerator Center (IUAC), New Delhi, India. The X-ray diffraction (XRD) patterns confirmed the formation of monoclinic and tetragonal phases and it was observed that XRD peak intensities increased up to the fluence of 5E12 ions/cm2 followed by opposite behavior at higher fluences. Atomic force microscope (AFM) study revealed the increased surface roughness after SHI irradiation. In addition to it, the formation of electronic transition states in optical band gap region and enhancement of absorption edge was observed from UV- visible spectroscopy (UV-Vis) results due to which direct band gap energy value decreased from those of un-irradiated samples. Photoluminescence (PL) broad emission spectra were determined using the excitation wavelength at 290 nm with the prominent peak at 415 nm which can be ascribed to Zr vacancies due to band edge emission as a result of free- exciton recombination. Rutherford backscattering spectrometry (RBS) technique was used for depth profiling and elemental composition in zirconia thin films. The expected role of electronic energy loss during ion irradiation to modify the properties of the material has been discussed.
关键词： PL,ZrO2 thin films,XRD,UV-Vis,AFM,RBS,SHI irradiation
更新于2025-09-09 09:28:46
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Humidity sensors based on AlN microcantilevers excited at high-order resonant modes and sensing layers of uniform graphene oxide
摘要： Resonant humidity sensors base on interdigital transducers (IDTs) excited microcantilevers are proposed for high sensitivity. The microcantilevers are coated with uniform graphene oxide (GO) thin films as sensing layers. For the first time, IDTs are used to excite piezoelectric microcantilevers to operate at very high-order resonant modes with intense signal. A small temperature coefficient of frequency (-23.6 ppm/?C) of the microcantilvers is obtained by using AlN/Si (surface highly doped) layered structure. Uniform and thickness-controllable GO films covering the surface of microcantilevers are formed by vacuum filtration. Compared with the normal electrodes excited sensor with the same structure size, the sensitivity of the IDTs excited sensor is increased from 9.67 to 84.41 Hz/%RH. The thicker GO film, the higher sensitivity of the humidity sensor. Very little humidity hysteresis (< 3%RH) of the sensors is observed in a wide test range from 10%RH to 90%RH. Moreover, the sensors have excellent short term repeatability, fast response and short recovery time (about 10 s).
关键词： Humidity sensors,interdigital transducers,uniform graphene oxide films,microcantilevers,high-order resonant mode
更新于2025-09-09 09:28:46