Probe Resistivity Measurements Research Articles

Preparation of silver nanowires with controlled parameters for conductive transparent electrodes

Silver nanowires (AgNWs) have excellent flexibility, unique optical transmittance and high conductivity. The polyol process is appropriate for preparing AgNWs due to its simplicity, effectiveness, low cost, and high yield. This work aims to investigate the effect of preparation parameters of the polyol process on the silver nanowires properties. The parameters include the controlling agent, molecular weight of the polyvinylpyrrolidone (PVP), the temperature, and the reducing agent. The amount of silver nanoparticles formed during preparation was used to determine the optimum preparation conditions. The transmission electron microscope (TEM) images showed minimal amount of Ag nanoparticles when using mixed molecular weight of PVP-40K, and PVP-1.3M at 150 °C with the assistance of copper chloride as a controlling agent. The prepared AgNWs had an average length of 3.7 µm and aspect ratio of 15.3. The fabricated electrodes were characterized using a scanning electron microscope (SEM) and four probe resistivity measurements. The electrical measurement of the AgNWs electrodes indicated that the surfactant thickness is a critical parameter in having low sheet resistance electrodes. Also, the optical transmission was affected by the amount of nanoparticles. The prepared electrode with high concentration of AgNWs and a minimal amount of nanoparticles exhibited 80% optical transmission.

Investigation on Errors of the Approximation Equation of Correction Factor G7 for Four-Point Probe Resistivity Measurement

Investigation on Errors of the Approximation Equation of Correction Factor G₇ for Four-Point Probe Resistivity Measurement

A broadband pulse amplifier for Joule heating experiments in diamond anvil cells.

Decades of measurements of the thermophysical properties of hot metals show that pulsed Joule heating is an effective method to heat solid and liquid metals that are chemically reactive or difficult to contain. To extend such measurements to hundreds of GPa pressure, pulsed heating methods have recently been integrated with diamond anvil cells. The recent design used a low-side switch and active electrical sensing equipment that was prone to damage and measurement error. Here, we report the design and characterization of new electronics that use a high-side switch and robust, passive electrical sensing equipment. The new pulse amplifier can heat ∼5 to 50 μm diameter metal wires to thousands of kelvin at tens to hundreds of GPa using diamond anvil cells. Pulse durations and peak currents can each be varied over three orders of magnitude, from 5 µs to 10ms and from 0.2 to 200A. The pulse amplifier is integrated with a current probe. Two voltage probes attached to the body of a diamond anvil cell are used to measure voltage in a four-point probe geometry. The accuracy of four-point probe resistance measurements for a dummy sample with 0.1 Ω resistance is typically better than 5% at all times from 2 µs to 10ms after the beginning of the pulse.

Machine Learning Aided Optimization of P1 Laser Scribing Process on Indium Tin Oxide Substrates

Present study employes a picosecond laser (532 nm) for selective P1 laser scribing on the indium tin oxide (ITO) layer and subsequent fine‐tuning of P1 scribing conditions with machine learning (ML) techniques. Initially, the scribing is performed by varying different laser parameters and further evaluate them via an optical microscope and two probe resistivity measurements. The corresponding scribing width and sheet resistance data are used as input databases for ML analysis. The classification and regression tree (CART)‐based ML analysis revealed that median pulse energy <5.7 μJ insufficient to separate the adjacent scribing regions. While pulse energy >5.7 μJ, APL > 35%, LSO > 46%, and processing speed ≥1250 mm s−1 gives ≥16 μm of scribing width. Further, the decision tree (DT) analysis showed that pulse energy of ≥8.1 μJ, and LSO ≥ 37% are required for electrically isolated lines. The feature importance score suggests that laser fluence and pulse energy determined the scribing width, whereas electrical isolation strongly depends on LSO and processing speed. Finally, the ML achieved conditions experimentally validated and reassessed via scanning electron microscope, and atomic force microscopy aligns well with optical microscope measurements.

Effect of Pr3+ Substitution at the A-Site on the Structural and Electrical Properties of Hole-Doped La-Based Manganites

In this study, the effect of praseodymium substitution at La-site on structural and electrical transport properties of La0.5Ba0.5MnO3 was investigated. Polycrystalline La0.5-xPr0.5x Ba0.5MnO3 (x = 0, 0.50, 1.00) were synthesized using a conventional solid-state method. The powder X-ray diffraction patterns show a single-phase orthorhombic distorted perovskite structure with space group Pnma. The Rietveld refinement analysis showed that the unit cell volume decreased as Pr3+ substitution increased which may be attributed to the different ionic radii of ions. Electrical resistivity measurements by using standard four-point probe resistivity measurement in a temperature range of 30 K to 300 K. As the Pr3+ concentration increases, metal-insulator transition, TMI decreases from 264K (x=0) to 157K (x=1.00) while resistivity increases from 1.16 Ω.cm (x = 0) to 20.3 Ω.cm (x =1.00). The decreased TMI are attributed to the decrease in tolerance factor which indicates enhancement in MnO6 octahedral distortion consequently reduce double exchange interaction. The electrical resistivity in the metallic region for all samples was fitted with the combination of domain/ grain boundary, electron-electron, electron-magnon and electron-phonon scattering processes. The resistivity behaviour in the insulating region for all samples was attributed to small polaron hopping model which revealed that the activation energies increased as Pr3+ content increased due to the enhancement in the distortion of MnO6 octahedral.

Extreme Dewetting Resistance and Improved Visible Transmission of Ag Layers Using Sub-Nanometer Ti Capping Layers.

As technology development drives the thickness of thin film depositions down into the nano regime, understanding and controlling the dewetting of thin films has become essential for many applications. The dewetting of ultra-thin Ag (9 nm) films with Ti (0.5 nm) adhesion and capping layers on glass substrates was investigated in this work. Various thin film stacks were created using magnetron sputtering and were analyzed using scanning electron microscopy/energy dispersive X-rays, Vis/IR spectrometry, and four four-point probe resistivity measurements. Upon annealing for 5 h in air at 250 °C, the addition of a 0.5 nm thick Ti capping layer reduced the dewet area by an order of magnitude. This is reflected in film resistivity, which remained 2 orders of magnitude lower than uncapped variants. This Ti/Ag/Ti structure was then deployed in a typical low-emissivity window coating structure with additional antireflective layers of AZO, resulting in a superior performance upon annealing. These results demonstrate an easy, manufacturable process that improves the longevity of devices and products containing thin Ag films.

Thermokinetic Study of Aluminum-Induced Crystallization of a-Si: The Effect of Al Layer Thickness.

The effect of the aluminum layer on the kinetics and mechanism of aluminum-induced crystallization (AIC) of amorphous silicon (a-Si) in (Al/a-Si)n multilayered films was studied using a complex of in situ methods (simultaneous thermal analysis, transmission electron microscopy, electron diffraction, and four-point probe resistance measurement) and ex situ methods (X-ray diffraction and optical microscopy). An increase in the thickness of the aluminum layer from 10 to 80 nm was found to result in a decrease in the value of the apparent activation energy Ea of silicon crystallization from 137 to 117 kJ/mol (as estimated by the Kissinger method) as well as an increase in the crystallization heat from 12.3 to 16.0 kJ/(mol Si). The detailed kinetic analysis showed that the change in the thickness of an individual Al layer could lead to a qualitative change in the mechanism of aluminum-induced silicon crystallization: with the thickness of Al ≤ 20 nm. The process followed two parallel routes described by the n-th order reaction equation with autocatalysis (Cn-X) and the Avrami-Erofeev equation (An): with an increase in the thickness of Al ≥ 40 nm, the process occurred in two consecutive steps. The first one can be described by the n-th order reaction equation with autocatalysis (Cn-X), and the second one can be described by the n-th order reaction equation (Fn). The change in the mechanism of amorphous silicon crystallization was assumed to be due to the influence of the degree of Al defects at the initial state on the kinetics of the crystallization process.

Electrical, optical and dielectric properties of polyvinylpyrrolidone/graphene nanoplatelet nanocomposites

In this study, polyvinylpyrrolidone (PVP) nanocomposite films containing GnP in four different volume fractions (φ = 0.00, 2.00, 4.08, and 5.91) were prepared by the solution casting method. UV–Vis absorbance spectroscopy, reflectance spectroscopy, and two-point probe resistivity measurement techniques were used to examine the optical, electrical, and dielectric properties of these films. Optical band gap energies of the PVP/GnP nanocomposites were obtained using the most commonly used Tauc, Kubelka-Munk (K-M), Absorbance Spectrum Fitting (ASF), and Derivative (DM) methods. The results obtained by Tauc, K-M, and ASF methods were found to be consistent with each other. In addition, basic optical parameters such as Urbach energy (Eu), refractive index (n), optical conductivity (σopt) and dielectric constant (ε) of the PVP/GnP nanocomposites were investigated. As the GnP volume fraction increased in the nanocomposites, the electrical conductivity, Eu, n, σopt and ε increased whereas Eg decreased. These nanocomposites produced by varying the GnP volume fraction are promising for using optics, electricity, optoelectronics, and many other industrial applications.

Precursor concentration-dependent structural, optical and electrical properties of titanium dioxide nanostructures

Titanium dioxide (TiO2) is a widely used material in many industries due to its unique properties, such as high refractive index, high chemical stability, and excellent photocatalytic as well as antimicrobial activity. The anatase phase of TiO2 is particularly important because it exhibits the highest photocatalytic activity among all TiO2 phases. The anatase phase TiO2 nanostructures are synthesized by the Sol-Gel route at a fixed calcination temperature of 600 °C and varying precursor concentrations i.e. the number of moles of TTIP and its influence on the structural, optical and electrical properties is investigated. The most prominent peak in XRD spectra is (101) which corresponds to anatase TiO2 with average crystallite size ranging from 20 nm to 37 nm at a TTIP concentration varying from 6.75 mmol to 16.9 mmol. With the increase of precursor concentration, the dislocation density decreases gradually. The SEM micrograph reveals the formation of nanosheets at lower concentrations and both nanosheets and nanoparticles at higher concentrations. From the UV–visible spectroscopy and four probe resistivity measurements, the energy band gaps and resistivity of the nanostructures are found to decrease with the increase of concentration. For making the theoretical prediction of our experimental results, the DFT was employed to simulate and calculate the structural and electronic properties of the synthesized materials which revealed the indirect band-gap of 1.94 eV for the anatase phase. The XRD spectra generated from the simulated anatase phase also matched the experimental XRD data.

Structure, microstructure and magneto-elastic property study on Co40Ni29Al31 ferromagnetic shapememory alloy ribbon

Ferromagnetic shapememory Alloys having huge magnetic field and stress-induced strain are suitable materials for sensors and actuators. Ni2MnGa being the prototype of these materials and because of its brittleness alternative systems CoNiAl/Ga were recently developed. CoNiAl being a ductile material because of its two-phase microstructure and the large range of transformation temperatures. In this line, a ribbon with nominal composition Co40Ni29Al31 was prepared using melt-spun technique. The structure and microstructure of the sample was determined using XRD and SEM. The transformation temperatures were determined using four probe method using a cryocooler within the temperature range of 4 K to 350 K. The elastic and magneto-elastic properties were studied using a Vibrating reed method within the temperature 80 K to 300 K. A constant magnetic field of 300 Oe is applied with a coil wound on the cryostat of the vibrating reed setup. As was expected the sample has two phases of microstructure, from the XRD data, a high amount of β phase with a few amount of γ phase was found and it was also replicated in SEM photographs. The phase fractions were found by fitting the XRD data with Reitveld refinement. The transformation temperatures of the sample were obtained from the four probe resistivity measurements, and they are TMs = 133 K, TMf = 83 K, TAs = 130 K and TAf = 179 K. From the sound velocity and internal friction study without and with the magnetic field interesting results were found. The martensitic and inter martensitic transformations were suppressed with the application of magnetic field. It was clearly seen in the sound velocity change plots as a function of temperature and the same was replicated in the internal friction plots. Such studies through light on the magneto-elastic coupling-related issues and are quite useful for the application of these materials for the Micro Electro Mechanical Systems at different operating conditions.

Need for structural health assessment of R.C.C. buildings

As civil engineering structures get older, there is a need to maintain, repair, retrofit and restore the structures once structural health of the structure is checked and found that it is deteriorating. The structural health is checked by performing various Non-Destructive Tests (NDT) or partially destructive tests on different structural members of the given structure and by calculating the service life and residual life of the structure. Sufficient service life remaining and good NDT results and conclusions allow for repair and retrofitting, of the deteriorating structure. The various Non Destructive Tests conducted are Rebound Hammer, Ultrasonic Pulse Velocity, Half Cell Potentiometer Test, Carbonation Test, Core Test, Cover Meter survey, Windsor Probe Test, Chloride Test, Sulphate Test, and Resistivity Measurements, Pull out tests, Radioactive Method of NDT. In the present study, two case studies of structural health monitoring and assessment of residual life of RCC buildings in Goa are undertaken and the need for retrofitting scheme is assessed. From the test results and analysis, it is observed that one structure can be retrofitted while the other structure cannot be retrofitted. Some of the retrofitting methods that will be used for the structure are Shotcrete, Fiber Wrap Technique, RCC Jacketing, and Plate Bonding.

Electromechanical Behavior of Al/Al2O3Multilayers on Flexible Substrates: Insights from In Situ Film Stress and Resistance Measurements

A series of Al and Al/Al2O3thin‐film multilayer structures on flexible polymer substrates are fabricated with a unique deposition chamber combining magnetron sputtering (Al) and atomic layer deposition (ALD, Al2O3, nominal thickness 2.4–9.4 nm) without breaking vacuum and thoroughly characterized using transmission electron microscopy (TEM). The electromechanical behavior of the multilayers and Al reference films is investigated in tension with in situ X‐ray diffraction (XRD) and four‐point probe resistance measurements. All films exhibit excellent interfacial adhesion, with no delamination in the investigated strain range (12%). For the first time, an adhesion‐promoting naturally forming amorphous interlayer is confirmed for thin films sputter deposited onto polymers under laboratory conditions. The evolution of Al film stresses and electrical resistance reveal changes in the deformation behavior as a function of oxide thickness. Strengthening of Al is observed with increasing oxide thickness. Significant embrittlement can be avoided for oxide layer thicknesses ≤2.4 nm.

Comprehensive Analysis of Phosphorus-Doped Silicon Annealed by Continuous-Wave Laser Beam at High Scan Speed.

We report an in-depth analysis of phosphorus (P)-doped silicon (Si) with a continuous-wave laser source using a high scan speed to increase the performance of semiconductor devices. We systematically characterized the P-doped Si annealed at different laser powers using four-point probe resistance measurement, transmission electron microscopy (TEM), secondary-ion mass spectroscopy, X-ray diffractometry (XRD), and atomic force microscopy (AFM). Notably, a significant reduction in sheet resistance was observed after laser annealing, which indicated the improved electrical properties of Si. TEM images confirmed the epitaxial growth of Si in an upward direction without a polycrystalline structure. Furthermore, we observed the activation of P without diffusion, irrespective of the laser power in the secondary-ion mass-spectrometry characterization. We detected negligible changes in lattice spacing for the main (400) XRD peak, showing an insignificant effect of the laser annealing on the strain. AFM images of the annealed samples in comparison with those of the as-implanted sample showed that the laser annealing did not significantly change the surface roughness. This study provides an excellent heating method with high potential to achieve an extremely low sheet resistance without diffusion of the dopant under a very high scan speed for industrial applications.

Effect of substrate temperature on the growth of Nb3Sn film on Nb by multilayer sputtering

We report on the fabrication of niobium tin (Nb3Sn) films by multilayer sequential sputtering on niobium at substrate temperatures ranging from room temperature to 250 °C. The multilayers were then annealed inside a separate vacuum furnace at 950 °C for 3 h. The material properties of the films were characterized by X-ray diffraction, scanning electron microscopy, energy-dispersive X-ray spectroscopy, atomic force microscopy, and transmission electron microscopy. The superconducting properties of the films were studied by four-point probe resistivity measurements from room temperature to below the superconducting critical temperature Tc. The highest film Tc was 17.76 K, obtained when the multilayers were deposited at room temperature. When the deposition temperature was raised to 250 °C, a significant reduction in voids was achieved while the film's Tc was 17.58 K.

Introducing gallium in silicon and thin film polysilicon using self assembled monolayer doping

• Gallium compound synthesized to form Ga molecular monolayers on silicon surface. • Ga monolayer doping in silicon and thin film polysilicon demonstrated. • Junction depth of 200 nm with a dose 1.6*10 15 Ga atoms/cm 2 demonstrated in n -Si. • Near uniform doping in polysilicon films is achieved with 20% electrical activation. Monolayer Doping (MLD) is a technique involving the formation of a self-assembled dopant-containing layer on the substrate. The dopant is subsequently incorporated into the substrate by annealing, forming a diffused region. Following MLD, samples were capped with silicon dioxide and rapid thermal annealed (RTA). In this work, gallium doping using MLD has been demonstrated. Gallium containing compound Tris (2,4 pentanedionato) gallium(III) was synthesized, and shown to be suitable for monolayer doping silicon substrates and deposited thin film polysilicon. Secondary ion mass spectroscopy (SIMS) and spreading resistance probe (SRP) measurements were performed to determine the dopant profiles and dopant electrical activation. These results showed that a dose of 1.6*10 15 atoms/cm 2 was received, and the gallium dopant produced a 0.2 µm junction in n -type silicon. For polysilicon, the entire 0.4 μm film was evenly doped, with a concentration greater than 10 19 atoms/cm 3 throughout.

Role of nickel in structural and mechanical properties of nc-WNNi sputtered nanocomposite coatings

Nanocomposites coatings offers a wide range of possibilities to promote hardness, oxidation resistance, wear resistance, etc properties significant for protective coatings. Finding new nanostructured coating with high hardness and thermal stabilities are the prime requirement of modern industries. In view of above, the nc-WNNi nanocomposite coatings were deposited using reactively sputtered method on silicon (100) substrate by varying the power of Nickel (Ni). The coatings were characterized by using grazing incidence X-ray diffraction (GIXRD), Field emission scanning electron microscope (FESEM), energy dispersive x-ray analysis (EDX), thickness profiler, four probe resistivity measurement and nanoindentation tester. Through GIXRD studies the desired face centered cubic W2N phase was confirmed, with decreasing crystallite size on increasing Ni power (content). FESEM image revels/suggest that at low Ni content, the film structure stabilized into well separated grains with the presence of grain boundary and were of uneven shape throughout. On increasing Ni power, the agglomeration increase and no clear signature of grain boundaries were visible. The resistivity of the films was found to be decreasing with increasing Ni content at different temperatures. Improved mechanical properties were observed at low Ni power (content), which drastically decreases with increasing Ni power. The highest hardness (H), elastic modulus (Er), elastic recovery (We), and resistance to plastic deformation (H3/E2) were obtained 26.60 GPa, 276.82 GPa, 69.80 GPa, 245 MPa respectively for nc-WN10Ni film. The nc-WN10Ni film shows the highest mechanical properties as compared to others.

Effect of two-step annealing on photoelectrochemical properties of hydrothermally prepared Ti-doped Fe2O3 films

Hematite (α-Fe2O3, bandgap ~2.1 eV) is a potential photoanode candidate for photoelectrochemical water splitting. In this work, we report the preparation of Fe2O3 with Ti4+ doping by hydrothermal treatment at 393 K and then annealing in the air at 873 K, with a second round of annealing in argon at 473 K. The two-step annealing process increased the photoelectrochemical performance of Ti-doped Fe2O3 on a fluorine-doped tin oxide (FTO)-coated glass substrate (FTO/Ti-Fe2O3) for water oxidation in 0.1 mol L−1 NaOH solution. Ti4+ doping was sourced from TiCl4 in ethanol solutions of various concentrations. An energy-dispersive X-ray spectrometer (EDS) analysis confirmed that the optimized Ti/Fe atomic ratio in the solution was ~3%, which showed the highest photocurrent densities in the linear sweep voltammetry and chronoamperometry measurements. The two-step annealed FTO/Ti-Fe2O3 generated a photocurrent density of 0.55 mA cm−2 at 1.50 V vs. reversible hydrogen electrode (RHE) under simulated one-sun illumination, which was approximately 3 times higher than that of the photoanodes annealed in air. Four-point probe resistivity measurements revealed that the two-step annealing resulted in a higher electrical conductivity than that of the samples annealed in air. The conductivity improvements induced by additional argon annealing at 473 K were ascribed to the increased donor density, which was confirmed by Mott–Schottky analysis and diffuse reflectance UV–visible–near-infrared spectra. We found that the strategy of Ti4+ doping and two-step annealing helped fabricate Fe2O3-based photoanode materials with better photocurrent density attributed to high electrical conductivity successfully.

Preparation and Characterization of PEDOT:PSS/TiO2 Micro/Nanofiber-Based Gas Sensors.

In this study, we employed electrospinning technology and in situ polymerization to prepare wearable and highly sensitive PVP/PEDOT:PSS/TiO2 micro/nanofiber gas sensors. PEDOT, PEDOT:PSS, and TiO2 were prepared via in situ polymerization and tested for characteristic peaks using energy-dispersive X-ray spectroscopy (EDS) and Fourier transform infrared spectroscopy (FT-IR), then characterized using a scanning electron microscope (SEM), a four-point probe resistance measurement, and a gas sensor test system. The gas sensitivity was 3.46–12.06% when ethanol with a concentration between 12.5 ppm and 6250 ppm was measured; 625 ppm of ethanol was used in the gas sensitivity measurements for the PEDOT/composite conductive woven fabrics, PVP/PEDOT:PSS nanofiber membranes, and PVP/PEDOT:PSS/TiO2 micro/nanofiber gas sensors. The latter exhibited the highest gas sensitivity, which was 5.52% and 2.35% greater than that of the PEDOT/composite conductive woven fabrics and PVP/PEDOT:PSS nanofiber membranes, respectively. In addition, the influence of relative humidity on the performance of the PVP/PEDOT:PSS/TiO2 micro/nanofiber gas sensors was examined. The electrical sensitivity decreased with a decrease in ethanol concentration. The gas sensitivity exhibited a linear relationship with relative humidity lower than 75%; however, when the relative humidity was higher than 75%, the gas sensitivity showed a highly non-linear correlation. The test results indicated that the PVP/PEDOT:PSS/TiO2 micro/nanofiber gas sensors were flexible and highly sensitive to gas, qualifying them for use as a wearable gas sensor platform at room temperature. The proposed gas sensors demonstrated vital functions and an innovative design for the development of a smart wearable device.

Structural, electrical transport and magnetoresistance properties of La0.7Ca0.3MnO3:ZnO nanocomposites

In the present communication, (1–x) La0.7Ca0.3MnO3 (LCMO) + (x) ZnO (x = 0, 0.10, 0.20) nanocomposites were synthesized by sol–gel method and studied for their charge carrier transport properties. The result of X–ray diffraction (XRD) confirms mixed phases of orthorhombic LCMO with hexagonal ZnO. ZnO admixing does not show any significant change in lattice parameters of LCMO however the peak intensity and crystallinity get suppressed with increase in ZnO content. The samples have been characterized for their electrical transport behaviors using four probe resistivity measurements which confirm that all the studied samples exhibit characteristic insulator to metal transition at temperature TP that decreases with increase in ZnO content. There is a discrepancy in the resistivity values between the LCMO:ZnO nanocomposite samples having the ZnO contents x = 0.10 and 0.20. Variations in the charge carrier transport parameters (i.e. resistivity and TP) with ZnO content have been attributed to the magnetic interactions between manganite and ZnO phases and phase separation scenario in LCMO manganite phase. Various models and mechanisms have been employed to understand the charge conduction processes across the lattices of studied nanocomposites. The largest magnetoresistance (MR) has been seen for x = 0.20 in the LCMO:ZnO nanocomposite which has been attributed to the different distribution possibilities of ZnO within the LCMO manganite lattice of the nanocomposite samples.

Electrical and mechanical behaviour of metal thin films with deformation-induced cracks predicted by computational homogenisation

Motivated by advances in flexible electronic technologies and by the endeavour to develop non-destructive testing methods, this article analyses the capability of computational multiscale formulations to predict the influence of microscale cracks on effective macroscopic electrical and mechanical material properties. To this end, thin metal films under mechanical load are experimentally analysed by using in-situ confocal laser scanning microscopy (CLSM) and in-situ four point probe resistance measurements. Image processing techniques are then used to generate representative volume elements from the laser intensity images. These discrete representations of the crack pattern at the microscale serve as the basis for the calculation of effective macroscopic electrical conductivity and mechanical stiffness tensors by means of computational homogenisation approaches. A comparison of simulation results with experimental electrical resistance measurements and a detailed study of fundamental numerical properties demonstrates the applicability of the proposed approach. In particular, the (numerical) errors that are induced by the representative volume element size and by the finite element discretisation are studied, and the influence of the filter that is used in the generation process of the representative volume element is analysed.