Measurements Of Electrical Properties Research Articles

Progress and development in multiple-probe scanning probe microscopes

Scanning probe microscopes (SPM) is one of the important tools for micro/nano-scale morphological characterization, physical property measurement and micro/nano operation. However, the traditional SPM has only a single probe and its function is limited. The emergence of multiple-probe scanning probe microscopes (MP-SPM) greatly expands the application of SPM. Characterizing the electrical transport properties of materials is very important for materials and microelectronics, because it can effectively guide synthetization of high-quality materials and fabrication of high-performance devices. Traditionally, directly measuring the conductivity of nanomaterials is performed using the nanofabricated electrodes connected to the nanomaterial of interest and the monolithic micro-four-point probes. However, photoresist and organic solvents may be left on the surface of the nanomaterial during nanofabrication, which will affect the intrinsic measurement of electrical transport properties. As for the monolithic micro-four-point probes, probe spacing is quite large due to the limitation of the manufacturing process and it will not change any more once they have been manufactured, which limits its flexibility. MP-SPMs multiple probes can act as measuring electrodes with precise localization, and the probe-sample distance can be controlled precisely, providing a means of flexible and non-destructive detection of micro/nanoscale electrical transport properties of samples. Micro/nano-manipulation systems help to manufacture microelectronic and photonic devices, renewable energy apparatus and biomedical diagnosis chip, etc. Typical micro/nano-manipulation systems are established based on optical tweezer, magnetic tweezer, scanning electron microscopy (SEM) and SPM. However, they all have limitations. Optical tweezer may damage the sample due to the continuously irradiated lasers. Magnetic tweezer has a poor ability to control the object quantificationally, and low resolution. The system based on SEM is restricted to a vacuum working environment. On the surface of the sample, traditional single-probe SPM can perform nano-manipulation, such as push and pull, but it is limited to two-dimensional space, and three-dimensional manipulation might be a great challenge. In addition, due to the lack of real-time visual feedback during the manipulation process, it always works at a time-consuming mode, such as scanning-manipulating-scanning. Although some researchers have designed augmented reality, local scanning and other methods to improve the efficiency of manipulation, the efficiency of manipulation is still low due to the serial procedure of single probe SPM. MP-SPM have been developed to provide multiple probes which can be controlled independently, and achieve complex nano-manipulation by cooperation among the probes. Furthermore, MP-SPM can image with a certain probe; and the imaging results, serving as priori/feedback information, can guide other probes manipulation, thereby it improves the efficiency and accuracy of micro/nano-manipulation. In this paper, the basic structure of MP-SPM, including the structure of multiple-probe scanning tunneling microscopy and multiple-probe atomic force microscopy, is presented. Furthermore, we also introduce the methods to decrease the distance between the probes and calibrate the multiple probes position and the principle of measuring the resistivity of materials using multiple-probe technology. Then we summarize the recent application advances of the measurement of electrical transport properties, the micro/nano-manipulation, the parallel imaging/ manipulation, and the mechanical properties at the micro/nano scale etc. Finally, we discuss the frontier development, the opportunities as well as the challenges of MP-SPM.

Temperature Dependent Electrical Transport Properties of High Carrier Mobility Reduced Graphene Oxide Thin Film Devices

We report temperature dependent electrical transport properties of high mobility reduced graphene oxide (RGO) thin films fabricated by pulse laser deposition. The temperature dependent (5K–350K) four terminal electrical transport property measurements confirm variable range hopping and thermally activated transport mechanism of the charge carriers at low (5K–210K) and high temperature (210K–350K) regions, respectively. The calculated localization length, the density of states near the Fermi level ( $E_{F}$ ), hopping energy, and Arrhenius energy gap provide useful information to explain the excellent electrical properties of the RGO films. Hall mobility measurement confirms ${p}$ -type characteristics of the thin films. The charge carrier Hall mobility can be engineered by tuning the growth parameters, and the measured maximum mobility was 1596 cm2v−1s−1. The optimization of the improved electrical property is well supported by structural properties such as the defect density, average size of sp2 clusters and degree of reduction, which were investigated by Raman spectroscopy and X-ray diffraction analysis.

Structure and Morphological Properties of In2O3 Nanostructure Prepared by Pulse Laser Ablation Method

A colloidal indium oxide (In 2 O 3 ) nanoparticles (NPs) were synthesized pulsed laser ablation (PLA) of indium plate placed on the bottom of the quartz vessel containing (3ml) of pure ethanol. The influence laser energy on the properties of the formed nano-particles were characterized by using atomic force microscopy (AFM), X-ray diffraction (XRD), Ultraviolet Visible (UV-Vis) technique, and electrical properties measurements. The XRD revealed the crystallization structure of In 2 O 3 nanoparticles and all the films having preferential orientation along (222) plane and intensity increases with increasing laser energy, The UV�Visible spectrum of the colloidal nanoparticles maximum absorbance show around the UV region, which indicates the formation of In 2 O 3 nanoparticles with energy gap about (3.6, 3.8 and 3.9) eV for different laser energy's (150, 300 and 500) mj respectively. The film conductivity decreased with increasing laser energy, while increasing in the the activation energy of In 2 O 3 nanopartical.

Determination of solid solution composition in Al alloys by electrical transport properties measurement and XRD method

The non-heat treatable aluminium alloys usually need homogenization before hot rolling to decrease the inhomogenities. In the process the segregations are dissolving and small precipitations are forming. The progress of the processes strongly depend on the temperature and the duration of the heat treatment. Topic of the research was to describe the dissolution/precipitation processes during the heat treatment. It was carried out by two different methods. Using electrical transport properties (resistance and thermo-power) measurement the percentage of the dissolved elements were calculated, and by X-ray diffraction method the cumulative effect was determined through lattice parameter change. The results of the methods were compared regarding to the heat treatment parameters.

Microstructural, morphological and electrical properties of sol-gel derived CoFe2O4 nanomaterials

CoFe2O4 nanomaterials have been synthesized through conventional sol-gel process by using CoCl2.6H2O and FeCl3 as precursors and citric acid is used as a capping agent. The as synthesized nanomaterials have been investigated thoroughly using x-ray diffraction (XRD) technique, scanning electron microscopy (SEM) and an impedance analyzer. The XRD patterns indicate the formation of body centered cubic spinel CoFe2O4 having cell constant 8.403 Å and the corresponding space group is Fd-3m, in which the Fe3+ and Co2+ ions occupied in octahedral and tetrahedral sites in the crystallographic orientations. The average crystallite size was found to be 30 nm. The SEM micrographs reveal that the synthesized nanomaterials (NMs) formed as octahedron and tetrahedron and the particles are well dispersed and contain some pores. We found 17.5% porosity of the nanomaterials that plays an important role in technological applications, e.g. water and chemical filtration related to bio-medical applications. Measurement of the AC electrical properties shows that dielectric constant increases up to 5.13 for 0.3 MHz and then it decreases with increasing applied frequency. Lower dielectric constant at high frequency region appears due to decreasing interfacial polarization and limiting grain boundary effect.

Electrical and optical property measurement of nickel-doped barium stannate synthesized by modified solid state sintering

Mechanical mixing of precursors followed by sintering at 1350 °C treated for 2 h were performed to synthesize nickel-doped barium stannate BaSn1-x NixO3 with x = 0.05, 0.10 and 0.15. The phase formation of synthesized material was identified by X-ray Diffractogram (XRD), which confirms a cubic perovskite structure as major constituent. The crystallite size and plane of orientation were calculated from the diffraction pattern. The morphological behaviour was studied from SEM images, and the chemical constituents of the synthesized materials were identified from EDX spectra. Bond formation and M—O coordination of the synthesized materials were identified from FTIR absorption spectra corresponding to symmetric and asymmetric stretches of bonding. Optical properties of the sintered samples were measured by UV—V spectroscopy. The bandgap of the synthesized material was calculated from the spectrograph. The photoluminescence characteristics were studied from PL spectra. The nanocrystalline behaviour of the material was assessed from HRTEM images and SAED patterns. The electrical measurements in terms of dielectric and ferroelectric properties were measured for various concentrations of doped materials.

Graphene oxide-tailored dispersion of hybrid barium titanate@polypyrrole particles and the dielectric composites

Dielectric composites with low dielectric loss recently attract increasing concerns of researchers due to the great potential applications in microelectronic devices. In this work, novel hybrid particles, which were composed of barium titanate (BaTiO3), polypyrrole (PPy) and graphene oxide (GO), were prepared through the in situ polymerization of PPy on the surface of BaTiO3 particles and the deposition of BaTiO3@PPy particles on the surface of the GO platelets. Morphology and microstructure characterizations showed that the ‘core–shell’-like BaTiO3@PPy particles were prepared and these particles exhibited homogeneous dispersion on the GO platelets. Then, two kinds of poly(vinylidene fluoride) (PVDF)-based composites, including PVDF/BaTiO3@PPy and PVDF/BaTiO3@PPy-GO, were fabricated. Different from the relatively homogenous dispersion of BaTiO3@PPy particles in the whole PVDF/BaTiO3@PPy composites, the BaTiO3@PPy-GO particles exhibited slight aggregation in the PVDF/BaTiO3@PPy-GO composites due to the GO-induced local aggregation of BaTiO3@PPy particles. The two kinds of particles exhibited good nucleation effect and mainly promoted the crystallization of α-form PVDF. Electrical conductivity and dielectric property measurements showed that the PVDF/BaTiO3@PPy-GO composites had lower electrical conductivity, smaller dielectric loss but higher breakdown strength compared with the PVDF/BaTiO3@PPy composites. The mechanism was mainly attributed to the presence of GO platelets, which restricted the formation of the conductive path in the composites.

Evaluation of dielectric cure monitoring for in situ measurement of natural rubber vulcanization

AbstractA novel in situ rubber cure monitoring system (RCMS) has been developed for monitoring the progress of vulcanization based on the measurement of electrical properties. The sensors connected to an LCR meter were embedded in the compression mold and measured changes in the electrical properties of rubber during vulcanization. Frequencies ranging from 0.75 to 100 kHz were probed for capacitance and conductance, and 5 kHz frequency was found suitable for monitoring natural rubber vulcanization. The results show that capacitance during curing correlated with the time profile of torque from a moving die rheometer (MDR). The scorch time and optimum cure time obtained from MDR and RCMS were reported. The degree of cure and the cure rate from two methods were compared. Good correlations between the alternative methods were observed, supporting the potential of in situ RCMS during the vulcanization of natural rubber.

Synthesis of La<sub>2</sub>NiO<sub>4+δ</sub> Nanofibers by Electrospinning Method and their Application

La2NiO4+σ nanofibers exhibiting typical Ruddlesden–Popper structure (K2NiO4) were fabricated by a facile electrospinning method. X-ray diffraction, scanning electron microscopy and transmission electron microscopy were used to analyze the structure, morphology and crystal process of the La2NiO4+σ nanofibers. For electrical properties measurement, uniaxially aligned nanofibers were directly collected and assembled into electrode. In our research, La2NiO4+σ phase forms above 873K with no impurity phase emerges during the thermal treatments. The nanofibers are smooth and uniform throughout the entire length and the grain is growing as calcination temperature increases. Furthmore, the La2NiO4+σ nanofibers own high mixed conductivity at 773K, laying good foundation for intermediate temperature solid oxide fuel cells application.

Evolution of polar nano-regions under electric field around ferro-paraelectric transition temperature and its contribution to piezoelectric property in Pb(Mg1/3Nb2/3)O3-0.30PbTiO3 crystal

As one of the most pronounced structural features, polar nano-regions (PNRs) is believed to have significant contribution to the outstanding piezoelectric property of relaxor-based ferroelectrics. However, direct experimental investigation on the connection between the PNRs behavior under electric field and piezoelectric responses is still insufficient. In this work, by the combined use of piezoresponse force microscopy, polarization light microscopy, and the electrical property measurements, we investigate the structure evolution from macro-domains to PNRs around ferro-paraelectric phase transition temperature (Tm, 140 °C) in Pb(Mg1/3Nb2/3)O3-0.30PbTiO3 single crystal. Most importantly, based on the corresponding analysis of unipolar strain-electric-field (S-E) curves at different temperatures and the direct observation of electric-field-induced structure evolution at Tm, we intensively investigate the response of PNRs to electric field and its contribution to piezoelectric property. We conclude that, under electric field, the active PNRs around Tm first serve as polar seeds to induce macro-domains from the non-polar matrix, then promote the switching of macro-domains. The large-field strain coefficient d33* in these two processes can achieve maximum of about 5410 pm/V and 61710 pm/V at Tm, and gradually decreases at higher temperature with lower PNRs content.

Abstract 4111: Water content based Electrical Properties Tomography (wEPT) for modelling delivery of Tumor Treating Fields to the brain

Abstract Objective: The purpose of this study was to investigate the application of Water content based Electrical Properties Tomography for mapping electrical properties (EPs) of brain tissues in the frequency range of 100-1000 kHz. Background: TTFields are electric fields with frequencies of 100-500 kHz that disrupt mitosis. TTFields are approved for the treatment of glioblastoma multiforme. Determining the EPs of brain tissues is important for understanding how TTFields distribute within the head. The EPs of tissues are heterogeneous, especially in the region of the tumor. Therefore methods that map EPs within the brain with high spatial resolution are desired. Water content based EP tomography (wEPT) is a method that utilizes the ratio of two T1w MRI images with different relaxation times (TRs) to map EPs based on empirically derived relationships between T1, water content (WC) and EPs. wEPT has been applied to map EPs of healthy brain at 128 MHz using typical WC and EP values of healthy tissues reported in the literature to derive the empirical models. Here we adapted wEPT to map EPs in the 100-1000 kHz range utilizing in-house measurements of WC and EPs from healthy bovine and tumor-bearing rat brain tissue. Methods: The empirical model connecting MRI images, WC and EPs in the 100-1000 kHz range were created using 32 tissue samples derived from three 3 calf brains and 1 CSF sample of a pig. For each sample, T1w MRIs with TRs {700, 4000} ms were acquired and the image ratio (Ir) between the images was calculated. EPs of samples were measured using parallel plates, and WC was measured by the wet-dry weight method. Curve fitting yielded empirical models connecting Ir, WC and EP. Next, T1w MRIs of in-vivo tumor-bearing rat brains and 6 ex-vivo pieces of calf brain were acquired, and the empirical curves described above were used to map WC and EP within the rat brains and the pieces of calf brain. EPs and WC were measured on 6 small samples excised from each imaged brain. For each sample, measured values were compared to the median WC and EPs extracted from the corresponding Regions of Interest (ROIs) in the wEPT map. Results: Anatomical structures and the tumor were clearly visible in wEPT maps. WC estimated using wEPT agreed well with measurements on excised samples. There was a clear connection between EPs estimated with wEPT and the measured values. However, in some samples large differences between wEPT-derived EP values and measurements were found. In particular, the differences between tumor and healthy tissues conductivity estimated using wEPT was significantly higher than the measured difference in conductivities within the corresponding excised samples. Conclusion: wEPT maps WC in healthy and tumor brain tissues and provides information on local electrical properties at frequencies of 100-1000 kHz. Further investigation is needed to clarify the relationship between WC and EP within this frequency range. Citation Format: Catherine Tempel-Brami, Cornelia Wenger, Hadas S. Hershkovich, Moshe Giladi, Ze'ev Bomzon. Water content based Electrical Properties Tomography (wEPT) for modelling delivery of Tumor Treating Fields to the brain [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 4111.

CuInTe2 thin films synthesis using one-step electrodeposition process: structural, optical, and electrical characterization

Polycrystalline CuInTe2 (CIT) films were grown onto ITO substrate by one-step electrodeposition technique using acidic aqueous solutions. In this study, the influence of the deposition time on CIT films properties was examined using six techniques, the X-ray diffraction, the scanning electron microscopy, the energy dispersive X-ray analysis, the optical transmittance, the Raman spectroscopy and the electrical properties measurements. The thickness of CuInTe2 films increases as the deposition time increases. The X-ray diffraction investigation of the films deposited during 5 and 10 min shows up only a tetragonal CuInTe2 chalcopyrite structure, with a preferred orientation along [112] direction. However, the films deposited during 15 and 20 min exhibits the CuInTe2 chalcopyrite structure as a main phase with In4Te3 as additional secondary phase. We have noticed a change in the preferred orientation axis of the prepared films as function of deposition time. The films show the direct allowed band gap and their energy band gap decreased from 1.06 to 0.99 eV as the deposition time increased from 5 to 20 min. Hall effect measurements show that the deposition time changes the conductivity type and films carrier concentration. The electrical conductivity is affected by the variation in the carrier mobility rather than by their concentration. The observed Raman modes in the films match well with those reported for single crystal CuInTe2 in the literature. All Raman spectra show the A1 mode at 127 cm−1 confirming the chalcopyrite crystalline quality of these films.

Effects of Grain Size on the UV‐Photoresponse of Zinc Oxide Thin Films Grown by Spray‐Pyrolysis

Zinc oxide films with different average grain size are deposited on glass substrates by spray‐pyrolysis at 425 °C. Samples are characterized by XRD, UV–Vis transmittance, FE‐SEM, and electrical properties measurements. The increase in conductivity observed under 365 nm wavelength illumination is evaluated in terms of grain size. Films with small grains (120 nm) show higher response with respect to films with larger grains (230 and 300 nm). A model considering resistivity and grain size for the prediction of the response of films in terms of UV‐to‐dark conductivity ratio is proposed and validated with experimental results.

Improving performance of OFET by tuning occurrence of charge transport based on pentacene interaction with SAM functionalized contacts

Optimized pentacene thin film transistors have been achieved by two technological self-assembled monolayers (SAM) treatments, with surface modification of 3-octadecyltrichlorosilane (OTS) monolayer on SiO2 dielectric layer and 2,3,4,5,6-pentafluorobenzenethiol (PFBT) monolayer on gold source/drain electrodes, respectively. Higher mobility and on/off ratio with 0.36 cm2 V−1 s−1 and >106 are consistently investigated for films deposited on PFBT compared to on OTS, which could be explained by the different occurrence charge transport near the semiconductor/dielectric and semiconductor/electrodes interfaces. It can be further confirmed by XPS and electrical property measurements. In the end, a high mobility increased up to 0.68 cm2 V−1 s−1 was obtained by cumulative treatments of the two SAM. In particular, the improving performance of the organic thin films transistor devices through tuning the charge transport with SAM layers highlighting the utility of surface modulations and controlling of charge transport of interfaces in nanoscale materials.

Electrical Properties of GeTe-based Ternary Alloys

Ge50-xSb x Te50 and Ge50-xBi x Te50 ternary alloys were synthesized by vacuum melting at 1273 K with the starting materials of Ge, Bi, Sb, and Te. The lattice structures were analyzed based on X-ray diffraction patterns, which could all be indexed to R3m rhombic structure. Electrical properties measurements revealed that the Ge-Sb-Te ternary alloys were p-type semiconductors with high electrical conductivity of 4.5×105 S∙m-1 near room temperature. And the maximum electrical property was obtained at Ge45Sb5Te50, with the power factor of 2.49×10-3 W∙m-1K-2 at 640 K. Due to the existence of secondary phases, the electrical conductivity of Ge-Bi-Te system was lower and Seebeck coefficient was higher comparing with those of Ge-Sb-Te system.

Preparation and electrical property of CaZr0.7M0.3O3 (M = Fe, Cr and Co) dense diffusion barrier for application in limiting current oxygen sensor

(M = Fe, Cr and Co) doped CaZrO3, CaZr0.7M0.3O3 (M = Fe, Cr and Co), was synthesized by solid state reaction method. Crystalline structure, microstructures, electronic conductivity, total conductivity and sensing performance were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), Hebb-Wagner, DC van der Pauw and voltammetry method, respectively. XRD measurements show that the CaZr0.7M0.3O3 (M = Fe, Cr and Co) samples belong to an orthorhombic perovskite structure. SEM measurements show that the CaZr0.7M0.3O3 (M = Fe, Cr and Co) samples have fine grains with average grain size of 0.5–2 μm. Electrical property measurements show that the CaZr0.7Fe0.3O3 and CaZr0.7Cr0.3O3 samples have the highest electronic conductivity and total conductivity in air, respectively. Sensing performance measurements show that limiting current-type oxygen sensors with 9YSZ solid electrolyte and CaZr0.7M0.3O3 dense diffusion barrier exhibit good limiting current (IL) plateau. Log IL depends linearly on 1000/T. IL depends linearly on oxygen partial pressure.

Superconductor-Insulator transition in sputtered amorphous MoRu and MoRuN thin films

This work shows the experimental results of the superconductor-insulator (S-I) transition for amorphous molybdenum ruthenium (MoRu) and molybdenum ruthenium nitride (MoRuN) films. These amorphous films onto c-plane sapphire substrates have been interpreted to be homogeneous by XRD and AFM measurements. Electrical and superconducting properties measurements were carried out on MoRu and MoRuN thin films deposited by reactive sputtering technique. We have analysed the data on Rsq (T) based on excess conductivity of superconducting films by the AL and MT term and weak localization and electron-electron interaction for the conductance. MoRu films which offer the most homogeneous film morphology, showed a critical sheet resistance of transition, Rc, of ∼ 2 kΩ. This values is smaller than those previously our reported for quench-condensed MoRu films on SiO underlayer held at liquid He temperature.

Electric Properties Measurement of Lentil

Abstract This paper contains the results of the electric properties measurement of lentil set. Electric measurements with use of these materials are of fundamental importance in relation to the analysis of quantity of absorbed water and dielectric heating characteristics. The aim of this paper was to perform the measurements of conductivity, dielectric constant and loss tangent on samples of lentil, the electrical properties of which had not been sufficiently measured. Measurements were performed under various moisture contents, and the frequency of electric field ranged from 1 MHz to 16 MHz, using a Q meter with coaxial probe. It was concluded that conductivity, relative permittivity and loss tangent increased with an increase in moisture content, and dielectric constant and loss tangent decreased as the frequency of electric field increased.

Development of Electrically Conductive Composite Sensors with the Addition of Functional Fillers

The paper presents the development results of "smart" pressure-sensitive fibre-cement compositematerials as well as thin-film coating sensors designed to detect disruptions of the base materialstructure. Basic material characteristics of fine-grained and coarse-grained cement matrices wereacquired during the research. The benefits and influence of conductive inorganic components,metallic components in the form of iron fillings and steel wires, and last but not least carbon-basednon-metallic fibrous reinforcement, have been verified. Thin-film epoxy resin coatings were enrichedwith amorphous carbon black, multi-walled carbon nanotubes (MWCNT) and natural micronizedgraphite. The article closely describes the measurement of electrical and electro-mechanical(piezoresistive) properties of conductive fibre-cement composites and thin-film organic coatings in anon-loaded state, during static loading and especially during dynamic ballistic and shock tests on thefall tower. Specific electrical characteristics and the course of change in electric conductivity wasexpressed as electrical resistivity (the real component of the impedance).The performed experiments confirmed excellent electrical conductivity of dense steel-fibrereinforced composites and graphite-doped hybrid fibre reinforced concrete. The coatings showedsignificant and permanent changes in impedance in the order of tens of ohms. The newly developedfibre composites and coating layers change the impedance during destructive and non-destructivedynamic loading tests. The impedance changed not only during failure of the matrix, but also in thecase of indirect impact. Moreover, carbon reinforced concrete with incorporated graphite showedsome piezoresistive properties. These detection materials were intended to be part of a ballistic-resistant monitoring system.

Modification of the optoelectronic properties of two-dimensional MoS2 crystals by ultraviolet-ozone treatment

We report the modification of the optoelectronic properties of mechanically-exfoliated single layer MoS2 by ultraviolet-ozone exposure. Photoluminescence emission of pristine MoS2 monotonically decreased and eventually quenched as ultraviolet-ozone exposure time increased from 0 to 10 min. The reduction of photoluminescence emission accompanied reduction of Raman modes, suggesting structural degradation in ultraviolet-ozone exposed MoS2. Analysis with X-ray photoelectron spectroscopy revealed that the formation of SO and MoO bonding increases with ultraviolet-ozone exposure time. Measurement of electrical transport properties of MoS2 in a bottom-gate thin-film transistor configuration suggested the presence of insulating MoO3 after ultraviolet-ozone exposure. These results demonstrate that ultraviolet-ozone exposure can significantly influence the optoelectronic properties of single layer MoS2, providing important implications on the application of MoS2 and other two-dimensional materials into optoelectronic devices.