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A comparison of the morphological and electrical properties of sol-gel dip coating and atomic layer deposition of ZnO on 3D nanospring mats
摘要： We report on the morphological and electrical properties, with (light) and without (dark) UV illumination, of conformal coatings of ZnO on silica nanosprings deposited by sol-gel and atomic layer deposition (ALD) for the first time. Field Emission Scanning Electron Microscopy (FESEM) imaging showed that both methods produce conformal coatings of ZnO on the nanosprings. The surface of the sol-gel coatings exhibited cracks at higher numbers of dipping/sintering cycles, while the morphology of ALD ZnO films were always smooth and devoid of cracks. The effective photoconductivity of the sol-gel ZnO coated nanospring mats increased nonlinearly with increasing coating thickness. The corresponding dark effective conductivity of the sol-gel ZnO coated nanospring mats also increased within the same thickness range. Alternatively, the effective photoconductivity of the ALD ZnO coated nanospring mats increased linearly with increasing coating thickness. The corresponding dark effective conductivity also increased within the same thickness range. The superior effective conductivity and photoconductivity of the ALD ZnO coated nanospring mats is attributed to the uniformity of the coating and the absence of cracks, which are observed for the thicker sol-gel ZnO coatings.
关键词： atomic layer deposition (ALD),semiconductors,sol-gel,nanosprings,field emission scanning electron microscopy,conductivity,ZnO
更新于2025-09-23 15:22:29
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[IEEE 2018 International Flexible Electronics Technology Conference (IFETC) - Ottawa, ON, Canada (2018.8.7-2018.8.9)] 2018 International Flexible Electronics Technology Conference (IFETC) - Optimizing the Electrical Conductivity of Screen Printed Silver Conductive Tracks by Post Treatment
摘要： Screen printed silver conductive tracks have been used or are being explored for applications in membrane switches, solar cells, radio frequency identification (RFID) antennas, diabetic testing strips, sensors etc. For many of these applications, optimizing the electric conductivity of the printed tracks is crucial. It has been noticed that the electric conductivity of the printed conductive tracks are highly dependent on the post-processing conditions. However, the understanding of the effect is limited. In this paper, preliminary study results show that ambient temperature drying followed by heat treatment offers the lowest resistance (highest conductance) for printed conductive tracks.
关键词： Electrical Conductivity,Printed Conductive Tracks,Post Thermal Treatment,Curing
更新于2025-09-23 15:22:29
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Characterization of the optical absorption, electric modulus, and thermal conductivity of poly(ethylene oxide) dispersed with alum and carbon black nanoparticles
摘要： Optical, electrical, and thermal properties of hybrid polymer thin films, made of poly(ethylene oxide) (PEO) filled with electrolyte alum salt of different concentrations, and doped with conductive carbon black (CB) nanoparticles (0.1 wt%), have been investigated. The optical properties were studied in the UV-visible wavelength range, thermal properties were studied as a function of temperature, filler content, and applied field frequency. The observed physical constants of the casted thin films like optical energy gap, energy tails, refractive index, thermal conductivity, impedance, dielectric constant, and electric modulus were determined. It was found that these measured quantities vary with the incident UV-wavelength, alum content, temperature and applied field frequency. The dependence of the electric modulus on frequency exhibit a relaxation peak occurs at 600 kHz.
关键词： Dielectric,Optical,Impedance,Thermal Conductivity,PEO,CB
更新于2025-09-23 15:22:29
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Derivation of Line Shape Function in the Optical Conductivity by a New Diagram Method
摘要： A new diagram method for the line shape function in the optical conductivity formula is introduced and the result obtained applying the method to an electron-phonon system is compared with that derived using the projection-reduction method. The result satisfies the population criterion, which states that the distribution functions for electrons and phonons should be combined in multiplicative forms and gives physical intuition to quantum dynamics of electrons in a solid. This method can be called the "KC diagram" method because it originates from the proper application of the Kang-Choi reduction identity and a state-dependent projection operator.
关键词： line shape function,optical conductivity,diagram method,population criterion,electron-phonon system
更新于2025-09-23 15:22:29
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High Channel Conductivity, Breakdown Field Strength, and Low Current Collapse in AlGaN/GaN/Si δ -Doped AlGaN/GaN:C HEMTs
摘要： This paper reports the AlGaN/GaN/Si δ-doped AlGaN/GaN:C HEMT device on silicon with high channel conductivity, high breakdown ?eld (E-?eld) strength, and low current collapse by using the Si-doped AlGaN back barriers. The Si δ-doped AlGaN back barrier was used to compensate for the reduction of channel conductivity as a result of a carbon-doped semiinsulating GaN buffer layer. The maximum drain current increases from 412 to 720 mA/mm, and peak extrinsic transconductance is improved from 103 to 210 mS/mm. Due to the reduction of electric ?eld between the gate and drain along the GaN channel by inserting the Si δ-doped AlGaN back barrier layer, it can effectively suppress the capture of electrons in channel by carbon-induced accepted traps in the GaN:C buffer. Combined with the high conductivity of Si δ-doped AlGaN back barrier and high resistance of GaN:C buffer, the device showed the high breakdown E-?eld strength and the low speci?c on-resistance. Our proposed device is observed to hold a gate–drain voltage of 769 V at 10 μA/mm (7-μm gate–drain spacing) and 0.53 mΩ · cm2 and the gate-to-drain electric ?eld corresponds to 1.1 MV/cm.
关键词： high channel conductivity,high-voltage device,Si δ-doped AlGaN back barrier,GaN,Current collapse (CC)
更新于2025-09-23 15:22:29
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Optical and electrical properties of thermally evaporated Se90Sb10 thin film
摘要： Chalcogenide Se90Sb10 thin ?lms are deposited by thermal evaporation from the bulk alloy. X-ray di?raction examination for the annealed ?lms shows the amorphous-crystalline transformation. This is bene?cial for optical disk data storage technology. The crystallinity is improved by increasing the annealing temperature. The ?lms annealed at relatively low temperatures exhibit highly transparence reaching to about 90% at incident light of wavelength of 900 nm. The as-prepared and annealed Se90Sb10 ?lms reveal an indirect allowed optical transition. The annealed ?lm at 473 K has an optical band gap of 1.676 eV which is suitable value for solar cell as photovoltaic application. Both the indirect optical energy band gap (Eg) and the oscillator energy (Eo) decrease whereas the oscillator strength (Ed) increases with increasing the annealing temperature. The annealing increases the conductivity and decreases the activation energy for conduction resulting in enhancement of ?lm properties for adapting to solar cells.
关键词： Electrical conductivity,Chalcogenide,Optical constants,Thin ?lms
更新于2025-09-23 15:21:21
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: A first-principles study
摘要： For environmental reasons there is a need for alternative Cd-free buffer materials in Cu(In,Ga)(S,Se)2 (CIGSSe) based thin film solar cells. In this context, β-In2S3 is one candidate material, whose optoelectronic properties can be affected by the presence of impurities. In this study, we investigate the impact of O and Cl impurities on the electronic and optical behavior of β-In2S3 by means of electronic structure calculations within density functional theory using hybrid functionals. We find that β-In2S3 is thermodynamically stable being in contact with both O and Cl reservoirs. Furthermore, we present evidence that O on interstitial sites (Oi) and Cl on 8c In sites (ClIn) cause low-temperature persistent electron photoconductivity. At room temperature, defect levels associated with Cl on S sites (ClS, ClS(cid:2) , and ClS(cid:2)(cid:2) ) get thermally ionized and release free electrons into the system. Thus, the n-type conductivity of the In2S3 buffer layer increases. O impurities on S sites, in contrast, are electrically inert. Hence, we conclude that intentional doping by Cl is a means to improve the properties of β-In2S3 serving as buffer material.
关键词： β-In2S3,hybrid functionals,O and Cl impurities,n-type conductivity,density functional theory,persistent electron photoconductivity,electronic structure calculations
更新于2025-09-23 15:21:21
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Influence of silicon dioxide medium on the structural and electrical properties of nickel zinc ferrite
摘要： Nickel zinc ferrite [(Ni 0:65 Zn 0:35 Fe 2 O 4)x / (SiO 2)1(cid:0)x where, x = 1.0, 0.85, 0.65, 0.50, 0.35, and 0.15] is synthesized using the glyoxylate precursor method. The synthesis, characterization, and electrical study of nickel zinc ferrites/SiO 2 powder with low dielectric constant, very low conductivity, and loss tangent with low frequency dispersion, suitable for good insulators, is reported here. X-ray diffraction, TGA, and FT-IR studies are employed for identifying crystalline phases and structure. Crystallite size is calculated by the Scherrer formula and Williamson–Hall equation and found to fall in the range of 4.9–25 nm. TEM of the samples shows spherical particles of uniform size distribution and the spotty rings of SAED patterns are analyzed for identifying the crystal planes. The study confirms a simple and efficient way to synthesize single-phase nickel zinc ferrite (NZFO) spherical particles of nano size ( (cid:25) 15 nm at 1000 ? C) with lower particle agglomeration in comparison to any other methods. Electrical studies are carried out using an LCR meter. The observed value of dielectric constant falls in the range of 10–80, loss tangent in the range of 0.05–0.4, and electrical conductivity in the range of 10 (cid:0)4 to 10 (cid:0)7 mho m (cid:0)1 . These values are respectively functions of temperature, frequency, and the ferrite content in ferrite/SiO 2 samples. A proper selection of ferrite concentration in the silica medium enables one to prepare NZFO/SiO 2 material of very low loss tangent with dielectric constant in the range of 10–80.
关键词： tetraethyl orthosilicate,dielectric constant,Nickel zinc ferrite,dielectric conductivity,loss tangent,ethylene glycol
更新于2025-09-23 15:21:21
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Highly conductive two-dimensional electron gas at the interface of Al2O3/SrTiO3
摘要： We create a two-dimensional electron gas at the Al2O3/SrTiO3/LaAlO3 heterostructures using pulsed laser deposition, which exhibits a decreasing sheet resistance with increasing growth temperatures of Al2O3 films. Structural characterizations of films are confirmed by cross-sectional transmission electron microscopy. Compared with these heterostructures with Al2O3 films deposited on pristine SrTiO3 and TiO2-terminated SrTiO3 substrates, the Al2O3/SrTiO3/LaAlO3 heterostructures are more conductive. X-ray photoelectron spectroscopy indicates the formation of oxygen vacancies at the SrTiO3 side of the interface, which results from the redox reactions by reducing SrTiO3 films. Furthermore, the existence of oxygen vacancies on the SrTiO3 side is verified by a blue-light emission.
关键词： Al2O3/SrTiO3/LaAlO3 heterostructures,pulsed laser deposition,oxygen vacancies,two-dimensional electron gas,conductivity
更新于2025-09-23 15:21:21
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Systematic microstructural development with thermal diffusivity behaviour from nanometric to micronic grains of strontium titanate
摘要： Strontium titanate is a promising candidate for applications in thermoelectric, thermal management applications, and modern electronic devices because of its desirable thermal stability, chemical stability, and semiconducting behaviour. However, the absence of its important systematic development, having grain size from several nanometric up to micronic size with evolving thermal diffusivity behaviour, triggers the need for filling up the vacuum. Two different heat treatments have been carried out onto the samples which were with presintering and without presintering. Nanometer-sized compacted powder samples were sintered from 500 to 1400 °C using 100 °C increments. The parallel characterizations of structural, microstructural and thermal diffusivity properties were systematically carried out. Interestingly, three significant value-differentiated groups: weak, moderate, and strong thermal diffusivity were observed, resulting from the influence of different phonon-scattering mechanisms through a systematic development of microstructural properties for both heat treatments.
关键词： Strontium titanate,Thermal conductivity,Thermal diffusivity,Microstructure
更新于2025-09-23 15:21:21