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Multivariable study on growth of diamond on diamond substrates by microwave? plasma chemical vapour deposition
摘要： Substrate temperature and methane concentration in Hydrogen (H2) gas mixture is the main source for increasing the growth rate, nucleation and grain size of a synthetic diamond. The downside of such an approach is reduced quality. By increasing the chamber pressure, although the quality can be improved, however, it leads to a decrease in the crystal growth rate. Thin diamond films were deposited under hydrogen (H2) and methane (CH4) gas mixture using microwave plasma chemical vapor deposition (MPCVD) technique. The effect of methane concentration (1-5%), growth temperature, and pressure on the nucleation of diamond thin films on diamond substrates was investigated. The growth temperature and pressure were maintained in the range of 925-950 ℃ and 72-75 Torr, respectively. Single crystal diamond (SCD) thin films have been prepared on diamond substrates, which play an important role in the application of the diamond detectors. Different dimensions of films were obtained on diamond substrates with different thicknesses such as 209.17 μm, 401.73 μm, and 995.03μm for the sample with 1%, 2% and 5% of methane concentration respectively. The roughness, as well as growth rate of these films, were also investigated and were found to be 5.02 μ/h and 4.23 nm, respectively for 5% methane by optimizing the substrate temperature at 950 ℃. Different characterization techniques were used to study the structural, morphological, and compositional properties of the deposited diamond films which confirmed the crystallographic order of the developed diamond film on the diamond substrates.
关键词： MPCVD,XRD,Diamond thin films,XPS,Raman spectroscopy,AFM,SEM
更新于2025-09-23 15:23:52
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Structural and dielectric properties of prepared PbS and PbTe nanomaterials
摘要： In this work, PbS and PbTe nanomaterials with various morphologies were synthesized by a hydrothermal method. The structural properties were investigated by using X-ray diffraction (XRD) and corresponding scanning electron microscopy together with their EDX analysis. Both the PbS and PbTe nanomaterials possess good polycrystalline structure. The crystallite size, determined from the XRD data, of PbS is 5 nm whereas the corresponding value of PbTe is 2.69 nm. SEM micrographs reveal that the prepared PbS nanomaterial has star-shaped structures, micro-flowers, some cubes, and semi-dendrites, whereas PbTe has semi-flower structures. Additionally, the dielectric properties have been studied in a broad frequency range from 0.1 Hz up to 1 MHz at temperatures from 298–423 K. The real and imaginary parts of the complex dielectric constant ε' and ε'' of PbTe are comparatively higher than those of PbS. Moreover, the dielectric data were analyzed on the basis of the electric modulus.
关键词： electric modulus,PbS,EDX,PbTe,dielectric properties,SEM
更新于2025-09-23 15:23:52
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Structural and vibrational properties of PVT grown BiTeCl microcrystals
摘要： High-quality BiTeCl microcrystals are grown by the physical vapor transport (PVT) method without using a foreign transport agent. The plate-like microcrystals with a developed (0001) surface are up to ~500 μm in diameter. The grown crystal phase composition was identified by the X-ray single crystal structure analysis in space group P63mc: a = 4.2475(6) ?, c = 12.409(2) ?, Z = 2 (R = 0.0343). The BiTeCl microcrystal phase purity was verified by Raman microspectrometry under excitation at λ = 632.8 and 532.1 nm.
关键词： PVT crystal growth,crystal structure,topological insulator,SEM,BiTeCl,Raman spectroscopy
更新于2025-09-23 15:23:52
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Study of the extrinsic properties of Copper doped Cadmium Sulfide thin film by hydrothermal assisted CBD method
摘要： Cadmium sulphide (CdS) and Cu doped CdS film were deposited onto commercially available FTO glass substrate by the hydrothermal assisted chemical bath deposition (HACBD). The effect of doping on the properties of CdS films were investigated. Optical, morphological, structural and photoluminescence properties of deposited films were investigated using UV-Vis spectroscopy, SEM, FTIR, X-ray diffraction and photoluminescence spectroscopy (PL). Lower value of the bandgap energy was observed for the Cu doped CdS films as compared to those of the undoped CdS films. XRD patterns reveal a cubic and hexagonal crystal structure phase with (1 1 1) and (0 0 2) as the preferential orientation having an average crystallite size of 18nm. SEM images reveal a change in the morphology of CdS and Cu-CdS thin films from spherical to disc like structures. PL spectra showed strong emission peak in visible region for both doped and undoped films. The associated of chemical bonds were investigated using FTIR spectroscopy.
关键词： Semiconductor,Doping,CdS,PL,SEM,Bandgap
更新于2025-09-23 15:23:52
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[IEEE 2018 15th International Conference on Control, Automation, Robotics and Vision (ICARCV) - Singapore, Singapore (2018.11.18-2018.11.21)] 2018 15th International Conference on Control, Automation, Robotics and Vision (ICARCV) - Detection and Compensation of Motion Error for Nanomanipulation Platform in Scanning Electron Microscope
摘要： Nanomanipulation system based on scanning electron microscope(SEM) with good real-time visual feedback and nanoscale observation resolution had high operability in a vacuum working environment. Different nanomanipulation tasks of carbon nanotubes (CNTs) are carried out through the nanomanipulation system in SEM. Nanomanipulation platform existed inherent manufacture errors, installation errors and other errors, and imprecise nanomanipulation system were also time-consuming and laborious for operators. This paper presentes a method of combining the visual feedback and feedforward control to detect and compensate the motion error of the multi-dimensional SmarAct nanomanipulation platform in the nanomanipulation system in SEM. This method reduces the motion error in the X-Y direction and achieved higher operating accuracy. At the different step speed, the motion error in the X direction and Y direction is 135.7nm and 112.9nm respectively. After the feedforward compensation, the motion error in the X direction and Y direction reduces to 61.3nm and 54.1nm respectively.
关键词： feedforward control,Scanning Electron Microscope (SEM),visual feedback,nanomanipulation
更新于2025-09-23 15:23:52
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Effect of short-circuit stress on the degradation of the SiO2 dielectric in SiC power MOSFETs
摘要： This paper presents the impact of a short-circuit event on the gate reliability in planar SiC MOSFETs, which becomes more critical with increased junction temperature and higher bias voltages. The electrical waveforms indicate that a gate degradation mechanism takes place, showing a large gate leakage current that increases as the gate degrades more and more. A failure analysis has been performed on the degraded SiC MOSFET and then compared to the structure of a new device to identify possible defects/abnormalities. A Focused-Ion Beam cut is performed showing a number of differences in comparison to the new device: (i) cracks between the poly-silicon gate and aluminium source, (ii) metal particles near the source contact, and (iii) alterations in the top surface of the aluminium source. The defects have been correlated with the increase in gate-leakage current and drain-leakage current.
关键词： Focused-Ion Beam,Short circuit,Gate-oxide breakdown,Gate oxide,Degradation,Defects,Reliability,SiC MOSFET,Failure analysis,SEM
更新于2025-09-23 15:22:29
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Temperature effect on structural, optical and NH<SUB align="right">3 gas sensing properties of TeO<SUB align="right">2 thin films
摘要： TeO2 thin films with different temperatures (400, 450 and 500°C) were deposited on glass substrates by thermal evaporation technique from a Te powder. XRD patterns indicate that as the temperature increases, the crystallisation improves. Observing the images obtained by SEM, it is seen that the grain size decreases as the temperature increases. The optical energy gap of the films was determined from transmittance and reflectance spectra. The optical energy gap decreased continuously from 3.95 eV to 3.80 eV with increasing temperature. Studying the effect of deposition temperature on NH3 gas measurement, it became obvious that as the deposition temperature increases, the sensitivity increases and the response and recovery times decrease.
关键词： scanning electron microscope,XRD,thin films,sensitivity,X-ray diffraction,energy gap,SEM,optical
更新于2025-09-23 15:22:29
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Improved Photocatalytic Properties of NiS Nanocomposites Prepared by Displacement Method for Removal of Rose Bengal Dye
摘要： Objective: The present work describes NiS nanoparticles were prepared by chemical displacement method using CTAB as a stabilizer. Method: For the source of Sulfide ion, we used thioacetamide as fuel and nickel nitrate as metal salt. NiS nanoparticles are p-type semiconductor. Band gap of NiS is 0.5- 0.6 eV and also reported to be a good photo catalyst in the degradation of pollutants. The structural, morphological, metal percentage and optical properties of as synthesized nanoparticles are investigated by using X-ray diffraction (XRD), UV-Visible spectra; Field emission gun scanning electron microscopy (FEG-SEM) with EDS, Fourier transforms infrared spectroscopy (FTIR), High-resolution transmission electron microscopy (HR-TEM) and Photoluminescence spectroscopy (PL). Results: The x-ray diffraction patterns revealed that the particles exhibited a crystal structure at the suitable temperature. The average particle size of the nanoparticles from the X-ray diffraction is about 22.8 nm and also Field emission gun scanning electron microscopy shows good morphology and exhibited clearly hexagonal shape. Conclusion: The Transmission electron microscopy (HR-TEM) shows the crystalline size of structures is 22 nm. Further, the Photocatalytic activity of Synthesized NiS nanoparticles was investigated by photo catalytic removal of Rose Bengal as a model of organic pollutant. It shows good photocatalytic activity against Rose Bengal dye (98.1%).
关键词： Nanoparticles,UV-Vis,FEG-SEM,EDAX,XRD,FTIR,HR-TEM,nickel sulfide
更新于2025-09-23 15:22:29
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Phase Evaluation of Pure Nanocrystalline Barium Stannate by Two Different Milling Activations
摘要： Pure nanocrystalline BaSnO3 is prepared by two methods: mechanical activation (planetary ball milling) and mechanical hand mixing in agate mortar followed by sintering for both at 1350 °C/ 2 h. The phase formations during synthesis are analyzed by x-ray diffraction (XRD) studies and the crystallite size is measured by Scherrer’s formula from the major peaks of the diffractogram. The nanocrystalline barium stannate having single phase simple cubic perovskite structure is synthesized with a crystallite size about 50 nm. Fourier transform infrared spectroscopy (FTIR) is done to determine symmetric and asymmetric stretching of the bonds formed and co-ordination of the ions within crystal structure. FTIR studies justify the phases developed by XRD since the molecular signature and co-ordination of cations are verified. Microstructure and morphology are observed by scanning electron microscopy (SEM), while energy dispersive x-ray analysis (EDX) is done to determine the presence of the required element of composition formation. Ultra violet-visible spectroscopy (UV-VIS) shows absorption spectra of the sample within the UV region, while the band gap is calculated using the Tauc relation. The band gap evaluated for nanocrystalline barium stannate is about 2–2.78 eV for indirect transition, while for direct transition it is about 2.78–3.14 eV. The value is observed to be close to that of semiconductor-based materials.
关键词： FTIR,UV-VIS,nanocrystalline barium stannate,EDX,high energy planetary milling,XRD,SEM
更新于2025-09-23 15:22:29
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Effect of Zinc Oxide nanorods on the structural, thermal, dielectric and electrical Properties of Polyvinyl alcohol /Carboxymethyle Cellulose composites
摘要： ZnO nanorods were prepared by chemical vapor deposition (CVD) have lengths ranging between 104.12 and 307.64 nm and diameters ranging between 21.17 and 55.88nm determined by transmission electron microscopy (TEM). Polyvinyl alcohol/carboxymethyl cellulose nanocomposites and Zinc oxide (ZnO) were prepared by casting method. The prepared samples were characterized by various methods. The results of XRD analysis depict the amorphous nature of these polymer samples and the degree of amorphousity is increased due to the addition process. The interaction of the ZnO NRs with the PVA/CMC blend was identified by Fourier transforms infrared spectroscopy (FTIR). The dispersion of dopant within the polymer matrix was supported by scanning electron microscopy (SEM). DSC and TGA was utilized to study the thermal behavior of the films and the highest conducting polymer material is lower the glass transition temperature. The conductivity and dielectric behaviors were analyzed by complex impedance spectroscopy as a frequency function at different temperature. The ac conductivity is found to obey Jonscher’s law, whereas dc conductivity is seen to exhibit Arrhenius behavior and increases with temperatures and the activation energy of the films with an increasing of ZnO NRs content was decreased. The dielectric properties of pure blend and nanocomposites have been enhanced due to the addition of ZnO NRs and are found to be highly temperature dependent. The frequency exponent (s) have been well fitted with the proposed correlation equation of the barrier hopping model. Significant increase in dc and ac conductivities in these nanocomposites samples makes them a potential candidate for electrochemical device applications.
关键词： AC and Dielectric parameters.,TEM,FT-IR,ZnO nanorods,SEM
更新于2025-09-23 15:22:29