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Investigation of the physical properties of Fe/Si for use in a Cu/Fe/Si solar cells contact
摘要： One of the drawback of the copper metallization, i.e. Cu/Si, for solar cells is the tendency of the metal to diffuse into silicon. This can deteriorate the P/N junction. Thus, a diffusion barrier is necessary. Iron has been found to be a potential candidate to be used as a barrier between Cu and Si. Before the fabrication of the Cu/Fe/Si contact, it is useful to investigate the properties of the Fe/Si ?rst and this is the objective of the present work. We have studied the variation of the electrical properties with the Fe thin ?lm thickness t and the deposition rate. The resistivity ρ values range from 8 to 36 μΩ.cm. Interesting behaviors of the square resistance RL, ρ and the coef?cient R are seen as a function of D/t, whereD is the grain size. Also, these nanometric Fe ?lms are characterized by a uniform surface with a relatively low surface roughness, a small strain (less than 1% in magnitude) and a sharp interface with no interdiffusion between Fe and Si; these are also good qualities for Fe to be used as a barrier between Si and Cu.
关键词： contact,Fe,solar cells,silicon,electrical properties
更新于2025-09-23 15:19:57
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Direct printing of performance tunable strain sensor via nanoparticle laser patterning process
摘要： Flexible electronics are attractive because of flexibility and portability. The circuits are printed on flexible substrates, which are delicate and heat-sensitive. Traditional photolithography, which uses high temperatures and corrosive chemicals, easily causes damages in flexible substrates. Here, we develop a low-cost nanoparticle based laser patterning process for fabrication of flexible electronics. Nanoparticles are sintered using a low-power laser as they are selectively deposited. Copper and silver particles were successfully deposited on paper and polyethylene terephthalate substrates. The effects of process parameters on deposition performance were studied to understand the process-structure–property relationship. The thermal effects of the laser on film morphology were observed. The sensitivities of the electrical properties with respect to the porosities at different laser power densities were analysed. With different laser energy levels, the process allows for selective deposition, properties control of printed patterns, and flexible substrate cutting. The fabrications of strain sensor and kirigami electronics were demonstrated.
关键词： strain sensor,electrical properties,hybrid manufacturing,Nanoparticle deposition,flexible electronics,process-structure–property relationship
更新于2025-09-23 15:19:57
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Effect of long-term mechanical cycling and laser surface treatment on piezoresistive properties of SEBS-CNTs composites
摘要： The piezoresistive behaviour of SEBS-CNTs nanocomposites was investigated to evaluate their potential applications as strain sensors. Composites containing from 3%wt. to 7%wt. of CNTs were processed by injection moulding in order to evaluate the percolation threshold. The piezoresistive response under flexural strain of nanocomposites with a CNTs content above the percolation threshold was then studied. The nanocomposites showing the most promising performance were tested under cyclic conditions. Conductive tracks were then processed on nanocomposites surfaces (with 3 and 4% of CNTs) by means of a laser treatment. Samples with optimized laser tracks were then submitted to 1000 stretching/releasing cycles, showing improved piezoresistive performance.
关键词： Piezoresistive behaviour,Polymer-matrix composites (PMCs),Surface treatment,Electrical properties
更新于2025-09-23 15:19:57
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The role of interfacial H-bonding in electrical properties of UV-cured resin filled with hydroxylated Al2O3 nanoparticles
摘要： Surface hydroxylation of crude Al2O3 (c-Al2O3) nanoparticles by H2O2 was conducted to tailor the electrical properties of UV-cured resin. The hydroxyl groups on Al2O3 particles were designed to establish hydrogen bonding between hydroxyl and carboxyl with that of UV/c-Al2O3 composites at the same filler content. It was found that the addition of 0.5 wt % h-Al2O3 increases the AC breakdown strength and volume resistivity by 15.5 % and 367.9 %, respectively. Our results suggest that the hydroxylation is an efficient way to improve the electrical properties of UV-cured resin nanocomposites, thus promoting stereolithography 3D printing in application of electrical and electronic field.
关键词： Stereolithography,Interfacial region,Hydrogen bonding,Nanocomposites,Interfacial strength,Trap levels,Electrical properties
更新于2025-09-23 15:19:57
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Hydration of Ti3C2Tx MXene: an interstratification process with major implications on physical properties
摘要： The MXenes, among which Ti3C2Tx is the most studied, are a large family of 2D materials with proven potential in a variety of application fields (e.g., energy storage and conversion, water purification, electromagnetic interference shielding, humidity sensor, etc). For most of these applications, MXenes properties depend, at least partly, on their water sorption ability and on the induced structural swelling, which is commonly considered a stepwise process, like in clay-like materials. In the present study, we rather evidence the systematic coexistence of different hydrates in MXene interstratified crystals. Hydration heterogeneity and related structure disorder are described from the quantitative analysis of X-ray diffraction data. This specific methodological approach allows disentangling the complex interstratification and rationalizing the prediction of MXene electrical properties. The widespread use of this approach paves the way for a systematic and thorough determination of MXene structure, including order-disorder, and thus for grasping the influence of structural disorder (hydration heterogeneity) on a large number of MXene physical properties (e. g. optical transparency, capacitance). Deciphering this complex structural disorder is also essential in the design of new MXene-based materials for a variety of applications (supercapacitors, batteries, water treatment…).
关键词： MXenes,Ti3C2Tx,electrical properties,X-ray diffraction,hydration,interstratification
更新于2025-09-23 15:19:57
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Optical, electrical and microstructural properties of SiC thin films deposited by reactive dc magnetron sputtering
摘要： In this study, amorphous silicon carbide (SiC) thin films of variable compositions were deposited on Si (100) and glass substrates by reactive direct current magnetron sputtering of high purity silicon target, using CH4 as reactive gas. The composition and the properties of the coatings have been modified by the change in the reactive gas flow rate from 5% to 50%. Spectrophotometer has been used to measure the optical transmittance and reflectance of silicon carbide thin films over the spectral range from 280 to 1000 nm. The optical constants such as refractive indices and the extinction coefficients of the films were calculated. The band gap values of the deposited films were further evaluated with respect to the gas flow rate. Transmittance values of SiC films changed from 85% to almost 0% in the visible light range. The optical band gap values of the films were altered from 1.7 to 2.7 eV. The activation energy was found to increase from 0.16 eV up to 1 eV and dark conductivity decreased from 7.42x10-4 to 1.06x10-9 Ω-1cm-1 while carbon concentration in the films increased. The results demonstrated that the optical and electrical properties of SiC films could easily be tailored by modifying Si and C concentrations in the coating composition, for the same film thicknesses.
关键词： optical properties,microstructural properties,Silicon carbide thin films,electrical properties,reactive direct current magnetron sputtering
更新于2025-09-19 17:15:36
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Electrical and optical properties of heavily Ge-Doped AlGaN
摘要： We report the effect of germanium as n-type dopant on the electrical and optical properties of AlxGa1-xN layers grown by plasma-assisted molecular-beam epitaxy. The Al content has been varied from x = 0 to 0.66, confirmed by Rutherford backscattering spectrometry, and the Ge concentration was increased up to [Ge] = 1×1021 cm?3. Even at these high doping levels (> 1% atomic fraction) Ge does not induce any structural degradation in AlGaN layers with x < 0.15. However, for higher Al compositions, clustering of Ge forming crystallites were observed. Hall effect measurements show a gradual decrease of the carrier concentration when increasing the Al mole fraction, which is already noticeable in samples with x = 0.24. Samples with x = 0.64-0.66 remain conductive (σ = 0.8-0.3 Ω?1cm?1), but the donor activation rate drops to around 0.1% (carrier concentration around 1×1018 cm?3 for [Ge] ≈ 1×1021 cm?3). From the optical point of view, the low temperature photoluminescence is dominated by the band-to-band emission, which show only spectral shift and broadening associated to the Burstein-Moss effect. The evolution of the photoluminescence peak position with temperature shows that the free carriers due to Ge doping can efficiently screen the potential fluctuations induced by alloy disorder.
关键词： germanium doping,molecular-beam epitaxy,optical properties,AlGaN,electrical properties
更新于2025-09-19 17:15:36
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Tuning of opto-electrical properties of hematite thin films using Co2+ doping
摘要： Hematite thin films have attracted widespread interest in recent years because of their advanced electronic and optical properties. Optical and electronic properties of hematite thin films can be enhanced/tuned using doping or additive-based strategies. An application oriented sol–gel method is used for the synthesis of cobalt (Co) doped hematite sol with variation in Co concentration in the range of 0–10 wt%. Hematite phase is observed in undoped thin films annealed at 300 °C under 500 Oe magnetic field for 60 min. Strengthening of hematite phase is observed with increase in Co concentration up to a value of 8 wt%. Bond angle with +ive tilt (i.e. ~ 19.74°) was observed in refined structural parameters for thin films prepared with Co concentration in the range of 0–8 wt%. Higher Co concentration, i.e. 10 wt%, results in decrease in crystallinity of the films along with smaller +ive tilt in bond angle (i.e. ~ 8.82°). High transmission (~ 88%) is observed for thin film prepared using dopant concentration of 8 wt% in the visible and infrared regions. The energy band gap varies from 2.42 to 2.25 eV with variation in Co concentration from 0 to 10 wt%. Relatively smaller band gap values are correlated with defect induced states in the band gap. Spectroscopic ellipsometry is used for calculation of refractive index and high values are indication of high density of thin films. Relatively higher value of dielectric constant (~ 183, log f = 5.0) along with lower value of tangent loss is observed at Co concentration of 8 wt%. Higher grain boundary resistance (1.88 × 105 ?) was observed at 8 wt% Co concentration. Variation in d.c. conductivity with dopant concentration is studied in detail using Jonscher’s power law. The value of frequency exponent (n) lies in the range of 0.88–0.98 (< 1) with variation in dopant concentration signifying that motion of charge carriers involves translational motion along with sudden hopping process. It is important to mention here that combined tuning of optical and electrical properties are observed in the present study with no change in phase pure hematite crystallographic structure.
关键词： Hematite thin films,Optical properties,Sol-gel method,Electrical properties,Dielectric constant,Transmission,Band gap,Cobalt doping
更新于2025-09-19 17:15:36
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Hybrid composite mats composed of amorphous carbon, zinc oxide nanorods and nickel zinc ferrite for tunable electromagnetic interference shielding
摘要： With the rapid growth of electronics and telecommunication industries, electromagnetic pollution is a serious concern to be addressed because it not only affects the sensitivity and performance of the devices but also affects human’s health. Here, we report lightweight hybrid composite mats, having porosity around 40%, composed of amorphous carbon, zinc oxide nanorods and nickel zinc ferrite for excellent electromagnetic interference (EMI) shielding in the X-band (8.2-12.4 GHz). The vibrating sample magnetometer measurement confirmed that the saturation magnetization value (Ms) of the composite materials enhances with the weight percentage of zinc oxide nanorods-nickel zinc ferrite (ZNF) powder, which leads to enhanced magnetic loss of the electromagnetic waves. With the thickness of 1.0 mm, the total EMI shielding effectiveness of the amorphous carbon composite was measured to be 25.70 dB which was further enhanced to 53 dB by the incorporation of the ZNF powder. Such high increment is attributed to the enhanced magnetic properties, interfacial polarization and dielectric properties of the composite. The synergistic combination of the materials results in the high reflection coefficient and absorption coefficient of the composites which were measured to be ~0.916 and ~0.083, respectively. Thus, the composites can shield up to 99.999% power of the electromagnetic waves which is shared by the 8.394% reflection and 91.605% absorption. Moreover, the magnetic, electrical and EMI shielding properties of the composites can be tuned by controlling the amount of ZNF powder in composites. Hence, the composite mats can be suitable for applications in defense and telecommunication.
关键词： A. Hybrid,A. Nano-structures,EMI shielding,B. Magnetic properties,B. Electrical properties
更新于2025-09-19 17:15:36
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Conducting Polymers || Electrical Properties of Polymer Light-Emitting Devices
摘要： In this chapter, we present a brief introduction to semiconducting properties of conjugated polymers and the motivation to apply this class of materials in electronic/optoelectronic devices such as polymer light-emitting diodes (PLEDs). We describe, in detail, the operating mechanisms of PLEDs, with particular focus on the effects of charge injection and transport and their dependence on the external electric field and temperature. The mechanisms of current injection from the electrodes into the organic semiconductor are initially treated using traditional models for thermionic emission and tunnelling injection. More recent models considering the influence of metal/semiconductor interface recombination and of energetic and spatial disorder in the injection currents are also introduced and discussed. In addition, models considering space-charge-limited currents and trap-filling-limited currents are employed to describe the charge transport characteristics in the bulk. Furthermore, we present a brief discussion on ideas concerning the effects of the disorder on the charge-carrier transport behaviour.
关键词： space-charge-limited currents,conjugated polymers,polymer light-emitting diodes,organic semiconductors,electrical properties
更新于2025-09-19 17:15:36