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The aim of this study was to assess whether electrical parameters (capacitance and conductivity) of fresh engine oils—tested over a wide range of measurement voltage frequencies—can be used for oil quality assessment and its identification, based on physicochemical properties. The study encompassed 41 commercial engine oils with different quality ratings (American Petroleum Institute (API) and European Automobile Manufacturers’ Association (ACEA)). As part of the study, the oils were tested for their total base number (TBN) and total acid number (TAN), as well as their electrical parameters, including impedance magnitude, phase shift angle, conductance, susceptance, capacitance and quality factor. Next, the results for all of the samples were examined for correlations between the mean electrical parameters and the test voltage frequency. A statistical analysis (k-means and agglomerative hierarchical clustering) was applied to group oils with similar readings, drawing on the values for all electrical parameters to produce group oils with the highest similarity to each other into clusters. The results show that the electrical-based diagnostics of fresh engine oils can serve as a highly selective method for identifying oil quality, offering much higher resolution than assessments based on the TBN or the TAN. This is further supported by the cluster analysis, with five clusters generated for electrical parameters of the oils, compared to only three generated for TAN- and TBN-based measurements. Out of all the tested electrical parameters, capacitance, impedance magnitude and quality factor were found to be the most promising for diagnostic purposes. The value of electrical parameters of fresh engine oils is mostly dependent on the test voltage frequency (with the exception of capacitance). The correlations identified in the course of the study can be used to select for those frequency ranges that offer the highest diagnostic utility.

In this paper, ultra-low level selective detection of bovine serum albumin (BSA) has been demonstrated, based on chemically derived graphene i.e., reduced graphene oxide (RGO) nanosheets. The working principle of the sensor is based upon change in conductance of the RGO nanosheets with different concentration of BSA. The change in conductance is based on the charge transfer between BSA and functional groups of RGO. The morphological and structural characterizations of RGO nanosheets were carried out by scanning electron microscopy (SEM), transmission electron microscopy (TEM), atomic force microscopy (AFM), Fourier transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD). Raman spectroscopy is performed to further validate the interaction between RGO sensing layer and BSA molecules. Electrical impedance spectroscopy is performed to observe the impedance variation when BSA interacts with RGO. The sensor device exhibits sensitivity of 10 nA/pM. The lower limit of detection (LOD) of the sensor is found to be 1 pM and response time around 35 s, confirming very high sensitivity for BSA. All electrical (current-voltage) measurements were carried out at 2 V bias for low power operation. The sensor exhibits highest sensitivity at 30 °C and for RGO thickness ~4 nm. The RGO based sensor device is selective towards BSA when compared to proteins like L-Histidine, HSA, BHB and Biotin. Our results suggest that RGO based devices are promising for low-cost, portable and real time detection of BSA at room temperature.

All-solid-state sodium batteries (ASSSBs) are attractive alternatives to lithium-ion batteries for grid-scale energy storage due to their high safety and ubiquitous distribution of Na sources. A critical component for ASSSB is sodium-ion conducting solid-state electrolyte (SSE). Here, we report a high-performance sodium-ion SSE with the recently developed bulk interfacial superionic conductor (BISC) concept. The ionic conductivity and areal conductance of the Na+ BISC at 25 °C reaches 6.5 × 10-4 S cm-1 and 260 mS cm-2, respectively. Using NaxCo0.7Mn0.3O2 (x ≈ 1.0, NaCMO) as the cathode active material, all-solid-state Na||NaCMO batteries exhibiting small overpotential and ∼180 cycle life are demonstrated under room temperature. This approach may also be used to prepare other metal ion, such as Mg2+, Al3+, and K+, based all-solid-state batteries.

The impedance, capacitance and conductance of aqueous sucrose polar solution are measured by employing impedance spectroscopy method and the current passing through the system for different DC voltages are measured implementing I-V method. The variation of electrical parameters with sucrose content in such solution exhibits a quasi-oscillatory nature, which is attributed to the random orientation of water and sucrose dipoles in the solution and their mutual interactions at the molecular level, including water-water, water-sucrose and sucrose-sucrose dipole interactions. To justify the quasi-oscillatory nature from analytical point of view, a theoretical model is developed on the basis of multi-body dipolar interactions of randomly distributed molecular dipoles. The experimental data agrees well with those obtained from the analytical model. The measurement of electrical parameters is performed within a frequency window of 100 Hz to 4 MHz for volume fractions of sucrose with respect to water, ranging from - pF - 266 pF, and 3 µS - 55 µS respectively for the sucrose volume fraction range considered. Current voltage measurements for the same concentration range are performed for a voltage swing between ±5 V and the obtained values vary from +20 µA to -25 µA. The study represents a deterministic approach to analyze the effective nature of a sucrose solution in terms of dielectric polarization of the system which finds application in sucrose quality assessments.

The effect of the NOA61 photopolymer organic interlayer on the electrical and dielectric properties of the Al/NOA61/p-Si/Al metal-polymer-semiconductor (MPS) device has been reported the first time. The device parameters of the device such as rectification ratio (RR), ideality factor (n), and barrier height (phi(B)) were determined from the current-voltage (I-V) measurements according to thermionic emission theory (TE). Series resistance, R-S, values were also calculated by Norde and Cheung methods in the range of 2.4-3 k omega. According to the reverse bias I-V measurements, the current was governed by Frenkel-Poole Emission (FPE) in the entire region. The voltage-dependent capacitance (C) and the conductance (G/omega) measurements were investigated at particular frequencies between 20 kHz and 1 MHz. The dielectric constant (epsilon '), dielectric loss (epsilon ''), loss tangent (tan delta), and the complex electric modulus (M) were calculated using the measured C and G parameters, and it was seen that the interface states and surface dipoles at the interfacial layer were effective in the behavior of the device in alternating current. Additionally, the morphological properties of the thin film were studied by scanning electron microscopy (SEM). We observed that (NOA61) organic interlayer may be a noticeable alternative to a variety of electronic applications.

A novel method for the detection of short pulses of gas at very low concentrations, the differential surface reduction (DSR), is presented. DSR is related to the temperature pulsed reduction (TPR) method. In a high temperature phase, e.g., at 400 ∘C, the surface of a metal oxide semiconductor gas sensor (MOS) is oxidized in air and then cooled abruptly down to, e.g., 100 ∘C, conserving the large excess of negative surface charge. In this state reactions of reducing gases with surface oxygen are strongly favored, which increases the sensitivity. Due to the large energy barrier between metal oxide grains caused by the excess surface charge, a highly precise electrical measurement at very low conductance (down to 10−11 S) is a prerequisite for this method. Moreover, the electrical measurement must be very fast to allow a good resolution of retention times. Applying the method to a doped SnO2 detector, gas pulses down to a dosage of 1 ppb times seconds can be detected. The gas transport inside the detector is simulated using the finite element method (FEM) to optimize the gas transport and to keep response and recovery time as short as possible. With this approach, we have demonstrated a detection limit for ethanol of below 47 fg.

The transport behavior of copper(I) nitrate electrolytes has been evaluated in the concentration range (4.0–100) × 10–4 mol·dm−3 in dimethylsulfoxide (DMSO), pyridine (Py) and nitromethane (NM) and their binary solvent mixtures containing 0, 0.20, 0.40, 0.60, 0.80, and 1.00 mol fraction of Py and NM at 298 K by conductance measurements. Parameters like limiting molar conductance (Ʌ0), association distance (R), Stokes radii (ri), and Walden product have been calculated using the molar conductance data. It is evident from the Stokes radii values that the ion solvation increases in the order Py > DMSO > NM indicating stronger solvation in the case of Py than for DMSO and than for NM. The above trend was further supported by Walden product values indicating more extensive solvation in Py.

AlGaN/gallium nitride (GaN) ion-sensitive field-effect transistors (ISFETs) were fabricated as pH sensors. The sensitivity of the AlGaN/GaN ISFETs was evolved with gate recess process and ammonium hydroxide (NH4OH) treatment. By performing the gate recess process, the threshold voltage ( ${V}_{\text {T}}$ ) of the ISFET increased from −3.33 to −0.31 V and the maximum conductance ( ${G}_{\text {M}}$ ) of the ISFET increased from 0.8 to 2 mS, with the current sensitivity of the pH sensor improving from 52.25 to $78.86~\mu \text{A}$ /pH. Further, after performing the ammonium hydroxide treatment, the ${V}_{\text {T}}$ of the ISFET increased from −0.33 to −0.14 V, with the current sensitivity of the pH sensor improving from 78.86 to $84.39~\mu \text{A}$ /pH. To characterize the surface conditions the X-ray photoelectron spectroscopy (XPS) was deployed. The results indicated that many nitrogen vacancies ( ${V}_{\text {N}}$ ) were introduced during the recess process, leading to a negative ${V}_{\text {T}}$ shift and a smaller potential sensitivity ( ${S}_{V}$ ), which can be improved by ammonium hydroxide treatment.

A unique field-effect transistor with an active channel composed of aptamers designed to bind to the Zika virus was fabricated. To immobilize the aptamers in the device channel, we used gold nanoparticles (AuNPs), a 20–40 nm thin film of sputtered gold (Au film), and a molecular sieve material zeolite. The aptamers were functionalized with a thiol end group that enabled them to bind with gold and most other materials. In the case of aptamer/AuNP, when Zika was added to the channel it reduced the channel conductivity from $4.4\times 10 ^{2}\text{S}$ /cm to 3.7 S/cm. The gate field effect clearly showed that the aptamer/AuNP channel is p-type with a relatively large transconductance of $300~\mu \text{S}$ ( $\text{V}_{DS} =2\text{V}$ ) compared to the Zika/aptamer/AuNP channel (also p-type) but with lower transconductance of $2~\mu $ S ( $\text{V}_{DS} =2\text{V}$ ). There was large amount of charge trapping (~1015 cm2) in Zika/aptamer/AuNP channel. In other cases of aptamer/Au film and zeolite channels, there were large changes in the channel conductance when Zika was added. Aptamer/Au and aptamer/zeolite channels were both n-type and their conductivities increased when Zika was added. Combination of AuNP and zeolite biosensing FETs can be used to design complimentary bio-FET sensors. We show that the gate voltage in FET biosensors can be used to increase their sensitivity (24 times in Zika/aptamer/AuNP), selectivity and dynamic range (by $10\times $ or more).

The adsorption performance of hydrogen selenide (H2Se) on the Zn/P-, Cd/P-, and Hg/P-modified graphitic carbon nitride (gCN) was theoretically investigated. The results of calculations revealed that with adsorption of H2Se on the modified gCN materials, the electrical conductivity, magnetic moments, electron transfer, and optimized structures of these systems considerably modulated. The calculated adsorption energy of H2Se on the Zn/P-, Cd/P-, Hg/P-modified, and P-doped gCN materials was −1.502, −2.141, −2.917, and −0.378 eV, respectively. The obtained results displayed that with modification of gCN by Zn/P, Cd/P, and Hg/P elements, the adsorption abilities of gCN remarkably improved. Furthermore, it was found that with the adsorption of H2Se and also embedding of Zn, Cd, Hg, and P elements, the conductance of gCN materials significantly increased. This phenomenon is attributed to the created new impurity energy levels close to the Fermi level. In addition, the results of total magnetization displayed that with adsorption of H2Se over the Hg-modified gCN material, the magnetic moment of the system remarkably changed. Also, the results of electron density and Lowdin charges analysis revealed that the adsorption energy of H2Se over the Hg/P-modified gCN is higher than the other gCN materials. Therefore, it can be deduced that the Hg/P-modified gCN is a promising candidate for detecting and removing of H2Se from the atmosphere. On the other hand, it can be concluded that the Hg/P-modified gCN system with the highest adsorption energy can be effectively used for gas sensor application.

This paper investigates the effect of pH on transport properties of silicon carbide nanowire field-effect transistor (SiCNW-FET) including the key parameters such as transconductance, resistivity, stability, and repeatability of the device towards harsh environment-sensing applications. Transport properties were investigated under different pH solutions ranging from pH 5 to pH 9. The device exhibited a high transconductance of 4.5 mS and a very low resistivity of 0.065 mΩ cm at pH 5 at a bias voltage of 2 V. The device showed an increase in conductance (from 2.66 to 4.5 mS) after applying the solution with pH 5 and then a substantial decrease in conductance (from 4.5 to 0.15 mS) with increasing the pH from 5 to 9 was observed. The changes in conductance can be attributed to the metal oxide/electrolyte binding sites model and to the hydrogen ions adsorption on the surface of the SiC nanowires altering the total surface charge density. The device exhibited almost a full recovery after rinsing with DI water, achieving good stability and repeatability. In consequence, this study would contribute to the development of low-power and cost-effective 3C-SiCNW-based FETs for use in the fields of bio- and environmental sensing, as well as biomedical applications.

We report on the capacitive memory of the WO3 nanowire (NW) MOS capacitor on Si substrate synthesized by glancing angle deposition (GLAD) technique inside an electron beam evaporator system. The field-emission gun scanning electron microscope (FEG-SEM) image shows the growth of vertically aligned WO3 NW with length of ~ 272.8 nm. The capacitance (C)–voltage (V) and conductance (G)–voltage (V) measurements were carried out at room temperature and in the range of 100 kHz to 1 MHz. The interface state density $${(D}_{it})$$ was also calculated and found to be 4.54 × 1010 eV−1cm−2 at 1 MHz. The electrical property such as series resistance (Rs) was also estimated. The calculated charge trap state density per area (N) is in the order of 1012 cm−2, and the mechanism was attributed to flat-band voltage. The WO3 NW device exhibits a memory window of ~ 5.96 V at ± 10 V. Good data retention up to 103 s and endurance up to 100 DC cycles at a read voltage of + 4.7 V were observed. A resistance ratio of approximately 3.34 was also estimated for the device.

The article presents an analysis of the influence of temperature on the electrical conductivity of composite polyacrylonitrile-polyaniline fibers (PAN/PANI). The fibers are obtained by synthesizing polyaniline directly in the spinning solution of fiber-forming polyacrylonitrile and characterized by X-Ray Diffraction (XRD), Differential Scanning Calorimetry (DSC), Scanning Electron Microscopy (SEM) methods. Electrical characterization of fibers is performed by current-voltage characteristic. The polarizing voltage of the electrodes in the range from -1 V to 1 V with a speed of 100 mV/sec is changed cyclically and linearly while simultaneously the current is measured. The current-voltage characteristic of the fibers is recorded at various temperatures in the range from -15 °C to 100 °C for 30 min. Based on the measurements, temperature changes in the conductance are determined in constant relative humidity. The current-voltage characteristics of the fibers in the ambient atmosphere with a relative humidity of 38 % are linear and symmetrical, which indicates the electron nature of the conductivity and the ohmic contact of the electrode-fiber. The characteristic of temperature conductance changes is not of a typical shape, it is parabolic. The conductance of the developed PAN/PANI fibers at 22 °C is about $1.50\cdot 10^{\mathrm {-4 { }}}\text{S}$ (6.7 $\text{k}\Omega$ ) and decreases below and above this temperature. The analysis of research results and literature data enables the determination of individual factors affecting changes in conductance of the tested composite fiber.

In this work, the electrostatic and radio frequency performances of 22 nm FDSOI nMOSFETs with p-type or n-type doped backplane (BP, highly doped layer of silicon below thin buried oxide) at cryogenic temperatures have been investigated. Greater enhancement of drain current $\text{I}_{\mathrm{ d}}$ , maximum transconductance $\text{g}_{\mathrm{ m,max}}$ and threshold voltage $\text{V}_{\mathrm{ TH}}$ values have been demonstrated at liquid nitrogen temperatures. Furthermore, FDSOI nMOSFETs with n-type BP achieve the maximum transconductance at lower bias voltage and smaller $\text{V}_{\mathrm{ ZTC}}$ , which is mainly due to its small threshold voltage. The variation of threshold voltage of BP-p devices is greater with the decrease of temperature. About 40% improvement of $\text{f}_{\mathrm{ T}}$ and 30% improvement of $\text{f}_{\mathrm{ max}}$ depended on the $\text{W}_{\mathrm{ f}}$ of devices have been shown. Relevant small-signal parameters (e.g., transconductance $\text{g}_{\mathrm{ m}}$ , gate capacitance $\text{C}_{\mathrm{ gg}}$ , gate resistance $\text{R}_{\mathrm{ g}}$ and output conductance $\text{g}_{\mathrm{ ds}}$ ) are also extracted for comparison and analysis. This study presents both 22 nm FDSOI nMOSFETs with p-type or n-type backplane as good candidates for cryogenic applications down to 77 K, and especially, BP-n FDSOI are more suitable for low power operation applications because of their lower threshold voltage. Similar $\text{g}_{\mathrm{ m.max}}$ and the peak values of RF FOMs can be obtained at lower bias voltage compared with BP-p devices.

In this study, in-situ MOCVD-grown SiN/AlN/Al0.05Ga0.95N HEMTs were fabricated using ALD-Al2O3/PECVD-SiO2 passivation. A high on/off current ratio of 109 and a low subthreshold swing of 64 mV/dec are achieved. The interface traps in the SiN/AlN/Al0.05Ga0.95 N structure are investigated using frequency-dependent capacitance-voltage and conductance measurements. The shift in threshold voltage, under a gate-bias stress of 4 V for 1000 s, is less than 0.06 V for the devices with 3 nm in-situ SiN as gate dielectric. This indicates excellent bias-induced threshold-voltage stability. A saturated drain current of 6.4 A, a specific on-resistance of 5.37 $\text{m}\Omega \cdot $ cm2, and a high breakdown voltage of 1014 V are observed for the devices with a gate width of 20 mm. Baliga’s figure of merit for the devices reaches $1.91\times 10^{8}\,\,\text{V}^{2}\Omega ^{-1}$ cm−2, which confirms its potential for high-power-switching applications.

Micro-hole voltammetry exhibiting rectified current-voltage curves was performed in hydrochloric acid by varying the lengths and the diameters of the micro-holes on one end of which a Nafion film was mounted. Some voltammetric properties were compared with those in NaCl solution. The voltammograms were composed of two line-segments, the slope of one segment being larger than the other. They were controlled by electric migration partly because of the linearity of the voltammograms and partly the independence of the scan rates. Since the low conductance which appeared in the current from the hole to the Nafion film was proportional to the cross section area of the hole and the inverse of the length of the hole, it should be controlled by the geometry of the hole. The conductance of the hydrogen ion in the Nafion film was observed to be smaller than that in the bulk, because the transport rate of hydrogen ion by the Grotthuss mechanism was hindered by the destruction of hydrogen bonds in the film. In contrast, the conductance for the current from the Nafion to the hole, enhancing by up to 30 times in magnitude from the opposite current, was controlled by the cell geometry rather than the hole geometry except for very small holes. A reason for the enhancement is a supply of hydrogen ions from the Nafion to increase the concentration in the hole. The concentration of the hydrogen ion was five times smaller than that of sodium ion because of the blocking of transport of the hydrogen ion in the Nafion film. However, the rectification ratio of H+ was twice as large as that of Na+.

The Pr0.67Ba0.22Sr0.11Mn1−xTixO3 (x = 0.05 and 0.075) manganites are synthesized using solid-state reaction route. All XRD patterns with narrow and intense diffraction peaks reveal that the samples are well crystallized. For electrical properties we measure the conductivity versus temperature (80–400 K) and frequencies (40 Hz–10 MHz). These measurements were made by admittance spectroscopy technique. The effect of titanium doping on the electrical properties of our compounds appears by semiconductor behavior. The variation of DC-conductivity with temperature presents two metal–semiconductor transitions. The first transition TMS bound by Mn3+/Mn4+ ratio but the second transition TSM depends to an extrinsic effect of grain boundaries. It was observed also that the conductivity decreases with titanium concentration, such behavior is associated to a reduction of double-exchange mechanism. The conduction mechanism is explained by thermally activated hopping of small polaron at high temperature range. The activation energy was evaluated of about Ea = 30 m eV for x = 0.05 and Ea = 61 meV for x = 0.075. The total conductance spectrum of Pr0.67Ba0.22Sr0.11Mn0.925Ti0.075O3 compound is well described by the Jonscher power law: $$G\left(w\right)={G}_{dc }+A{\omega }^{n}$$ . Impedance study for the sample with x = 0.075 indicates the presence tow metal–semiconductor transitions and a non-Debye relaxation phenomenon related to a grain and grain boundary medium. Also, the modulation of the material by an electrical equivalent circuit show high values of grain boundary medium capacity.

Precise measurement of the conductivity of FeCl3 in distilled water at 303.15 and 308.15 K temperature were measured. The specific conductivities exhibited a sharp increase with increase in concentration within the concentration range investigated (0.001 to 0.100 mol per liter. The decrease in the conductance with decrease in concentration is due to decrease in the number of ion per unit volume of the solution. Also decrease in conductance with decrease increase in temperature due to decrease in the speed of the ions.

Nanocrystalline gas sensitive material based on Perovskite type La0.8Ca0.1Pb0.1FeO3 (LCPFO) sample has been prepared by the sol-gel method with the citric acid route. The gas sensitivities under different temperatures of the (LCPFO) compound have been investigated toward the two NH3 and CO reducing gases. The synthesized compound has been analyzed by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy dispersive spectroscopy (EDS) and atomic force microscopy (AFM). It was found that the compound exhibits an orthorhombic symmetry with the Pnma space group. The effect of the experiment environment (under vacuum and air) on the conductance and activation energy Ea of the LCPFO compound has been evaluated. The Ea values have been found to be in the range of 0.43 eV

Tuberculosis is one of the life-threatening infectious diseases caused by the obligate pathogenic bacterium Mycobacterium tuberculosis (M. tuberculosis). The current M. tuberculosis detection approaches cannot satisfy the requirement for early clinical diagnosis because of long detection time as well as low specificity. In our study, an electrochemical M. tuberculosis sensor was constructed by using specific fragment of 16S rDNA of M. tuberculosis H37Ra as target biomarker, peptide nucleic acid (PNA) as capture probe and highly conductive two-dimensional Ti3C2 MXenes as the signal amplified transduction material. After the hybridization between PNA and the specific fragment of 16S rDNA on the substrate of PNA-AuNPs nanogap network electrode, the target fragments were directly linked with conductive Ti3C2 MXenes by strong interactions between zirconium-cross-linked Ti3C2 MXenes and phosphate groups of the target fragments. The linking of Ti3C2 MXenes to the hybridized target fragments would bridge the gaps of the interrupted AuNPs in the nanogap network electrode and forming the conductive connection to cause the change in conductance between the electrodes. This conductance change could be used for M. tuberculosis detection. The limit of detection (LOD) of proposed method was 20 CFU mL−1, and detection time was 2 h. Proposed method would find potential application in rapid detection of M. tuberculosis.

In this study, Au/n-Si structures with PVP polymer interlayer were fabricated and characterized using capacitance/conductance-voltage-frequency (C/G-V-f) measurements. Obtained electrical parameters were found to be sensitive to frequency due to polymer interlayer, changes of traps/states (D-it/N-ss) level, interfacial/dipole polarization. The dispersion in C and G in depletion region is due toN(ss)/polarization, while the dispersion in accumulation region is due to interlayer/series resistance (R-s). The voltage-dependent profiles ofN(ss)andR(s)were derived using the methods of low-high frequency capacitance/Hill-Coleman and Nicollian-Brews, respectively. The width of depletion layer (W-d) and barrier height (phi(B)) values increase with increasing frequency almost linearly. On the other hand,R(s)decreases with increasing frequency whereas the maximum electric field (E-m) exhibits opposite behavior. The high frequency C/G-V plots were corrected to reveal theR(s)effect on them. The experimental results indicate that the growth of PVP interlayer by spin coating at the Au/n-Si interface yields a preferable and suitable device compared to devices with conventional insulating interlayer due to some advantages of polymer interlayers such as low-cost/weight, flexibility, and easy grown processes.

The effects of copper nanoparticles (CuNP) dispersion on the optical and electrical properties of mesoporous SBA-15 like silica were investigated. Full characterization of the resulting SBA-15-Cu through X-ray diffraction (XRD), thermogravimetry analysis (TGA), scanning electron microscopy (SEM), energy dispersion X-ray fluorescence (ED-XRF), diffuse reflectance (DRS) and Fourier Transform Infrared spectroscopy (FT-IR) revealed marked changes in the structure properties after copper incorporation. Slight decrease in the optical band gap energy in the SBA-15-Cu was also noticed. The shifts towards higher wavelengths are attributed to change in the acceptor capacity level induced by iron nanoparticles. Measurements of Z' and Z" in temperature showed an improvement in proton mobility of SBA-15-Cu. Deeper insights in the capacitance and conductance by impedance spectroscopy measurements over a wide range of frequencies at various temperatures suggest that CuNPs interaction with SBA-15 surface and silanol deprotonation can be, at least partly, responsible for conductance improvement. The above properties make these materials to be regarded as efficient materials for potential applications in electronics.

Graphical abstract, Highlights • CO2 gas pressure-dependent conductance (G(P)) of vanadium-oxides nanowires (VON) from vacuum to 45 bar decreases with the increase of the gas pressure. • Increase in the interlayer distance and decrease in phonons for V3—O and V—O—V bonds were observed after high CO2 pressure exposure. • Oxidation of V4+ to V5+ due to high CO2 pressure is the reason for these changes. • Oxidative dehydrogenation process with VON catalyst under high pressure CO2 atmosphere has potential to improve the efficiency., In the oxidative dehydrogenation (ODH) process that converts ethylbenzene to styrene, vanadium-based catalysts, especially V2O5, are used in a CO2 atmosphere to enhance process efficiency. Here we demonstrate that the activation energy of V2O5 can be manipulated by exposure to high pressure CO2, using V2O5 nanowires (VON). The oxidation of V4+ to V5+ was observed by X-ray photoelectron spectroscopy. The ratio of V4+/V5+ which the typical comparable feature decreased 73.42%. We also found an increase in the interlayer distance in VON from 9.95 Å to 10.10 Å using X-ray diffraction patterns. We observed changes in the peaks of the stretching mode of bridging triply coordinated oxygen (V3—O), and the bending vibration of the bridging V—O—V, using Raman spectroscopy. We confirmed this propensity by measuring the CO2 pressure-dependent conductance of VON, up to 45 bar. 92.52% of decrease in the maximum conductance compared with that of the pristine VON was observed. The results of this study suggest that ODH process performance can be improved using the VON catalyst in a high pressure CO2 atmosphere.

A study has been made of the activation energy of the conductance of a p–n-4H-SiC 〈Al〉 structure created through the doping of silicon carbide with aluminum. The doping was implemented by a novel method of low-temperature diffusion, in which the diffusion of aluminum in silicon carbide is stimulated by a carbon- and silicon-vacancy flux produced by the oxidation of the silicon surface.

The dielectric properties and ac conductivity of an electronically irradiated layered TlGaS2 single crystal are studied in the frequency range of 5 × 104–3.5 × 107 Hz. It is established that electron irradiation of TlGaS2 single crystal samples with doses of 2 × 10l2 to 2.4 × 1013 e/cm2 leads to a decrease in the real component (e') of the complex dielectric permittivity in a high-frequency region (f > 106 Hz) and an increase in its imaginary component (e''), the dielectric loss tangent (tanδ), and ac conductance (σac) across the layers in the entire studied frequency range. At irradiation doses of 2 × 10l2 to 2.4 × 1013 e/cm2, losses in the reach-through conductivity of TlGaS2 occur, and, as the electron irradiation dose accumulates, the dispersion of e'' and tanδ increases significantly. In the frequency range of f = 5 × 104–2 × 107 Hz, in the irradiated TlGaS2 samples, the ac conductivity changes according to the law σac ~ fn (where n = 0.7–0.8), which is typical of the hopping mechanism of charge transfer via localized states near the Fermi level. The parameters of localized states in TlGaS2 (the density of the states near the Fermi level and their energy spread) are estimated versus the electron irradiation dose.

Au/Ti/HfO2/n-GaAs MIS (metal/insulating layer/semiconductor) diodes were fabricated by atomic layer deposition technique and their electrical properties were investigated in detail by the help of current-voltage (I-V) and admittance measurements in the temperature range of 60-320 K. Together with the surface morphology analysis on the HfO2 thin-film layer, main electrical parameters such as series resistance (R-s), zero bias barrier height (phi(Bo)), ideality factor (n), impedance (Z) and phase angle were determined and effects of temperature on these parameters of the MIS diodes were discussed. The evaluation of I-V data exhibits a decrease in R-s and phi(Bo), however an increase in n, with a decrease in temperature. Temperature-dependent conductance (G) and capacitance (C) characteristics of the MIS diode were investigated at 1000 kHz in the voltage interval in between - 3 and 2 V. G and C values were found in a direct relation with the change in temperature. On the other hand, Z values showed an inverse proportionality with temperature. The phase angle versus voltage plots were evaluated at different temperatures (60-320 K) at 1000 kHz and the obtained results indicated that the device behaves more capacitive in the voltage range of - 3 V and about 0.4 V for all temperature, and phase angle decreases with increasing temperature from 0.4 to 1.6 V. In addition, the interface state density (D-it), the effective oxide charge density (Q(eff)) and effective number of charges per unit area (N-eff) of the fabricated diodes were investigated over temperature range 60-320 K in which these values were found in a decreasing trend with increasing temperature. WOS:000527502800002 2-s2.0-85084081639

Semiconducting single-walled carbon nanotubes (s-SWCNTs) have been used in electrical transducers for environmental and health monitoring due to their quasi ballistic electron transport, efficient transconductance, high carrier mobility, good on/off ratio, excellent mechanical properties, etc. Herein, we have prepared a non-enzymatic pesticide sensor to selectively detect methyl parathion (MP, which is a restricted use pesticide according to the EPA) using a silver–zinc oxide (Ag–ZnO) composite decorated s-SWCNT based field-effect transistor (FET). The Ag–ZnO/s-SWCNT film is also characterized by using field-emission scanning electron microscopy (FE-SEM), energy-dispersive spectrometry (EDS), X-ray diffraction (XRD), Fourier-transform infrared (FT-IR), ultraviolet-visible-near infrared (UV-vis-NIR), Raman and photoluminescence (PL) spectroscopies. The electrical response of the Ag–ZnO/s-SWCNT–FET was measured under ambient conditions in the presence and absence of MP. The hydrolysis of MP took place due to the potent catalytic activity of Ag–ZnO, which led to changes in transistor conductance. Based on this, detection of the different concentrations of MP was demonstrated by using Ag–ZnO/s-SWCNT–FET. The Ag–ZnO/s-SWCNT–FET device showed a linear response from 1 × 10−16 M to 1 × 10−4 M MP with a limit of detection (LOD) of 0.27 × 10−16 M in 0.1 M phosphate buffer solution (PBS). In addition, Ag–ZnO/s-SWCNT–FET exhibited acceptable reproducibility and repeatability when employed for MP detection. Moreover, the proposed FET sensor was highly stable under ambient conditions. Finally, the accurate detection of spiked MP is demonstrated in soil and rice samples with good recovery.

Flexible perovskite solar cells (FPSCs) with excellent anti-bending ability are successfully fabricated, in which the novel cathode PEDOT:PSS:Li/ITO(20 nm) is used. With a bending radius of 1.0 cm, when the bending cycle, N, equals 0, 10 000 and 20 000, the power conversion efficiency as a function of N, η(N), is 13.91%, 10.86% and 3.45%, or 100%, 78% and 25% of η(0), respectively. During bending along an edge of our FPSC, we found that the reductions of layer conductance, φ(N), for the cathode, electron transport layer, perovskite layer, and hole transport layer are essential for reduction of η(N) due to bending. For each of the above constituent layer “i”, when N increases, the normalized layer conductance fi(N), i.e. φi(N)/φi(0), consistently and markedly decreases, and its reduction rate consistently increases. η(N) can be well fitted by the product of fi(N)mi for the mentioned four layers, and the power, mi, is determined by fitting. The “i” for the cathode is marked as “1”, and when the cathode is improved as mentioned, not only the reduction rate of f1(N) with N sharply decreases, but also the power, m1, largely decreases from 1.52 to 0.0076. When the novel cathode is used, the influence of its layer conductance reduction on η(N) reduction due to bending greatly decreases.

Lead Zirconate Titanate (PZT) sensors have become popular in structural health monitoring (SHM) using the electromechanical impedance (EMI) technique for damage identification. The vibrations generated during the casting process in concrete structures substantially impact the conductance signature’s (real part of admittance) magnitude and sensitivity. The concept of smart sensing units (SSU) is presented, composed of a PZT patch, an adhesive layer, and a steel plate. It is embedded in the concrete structure to study the impact of damage since it has high sensitivity to detect any structural changes, resulting in a high electrical conductance signature. The conductance signatures are obtained from the EMI technique at the damage state in the 10–500 kHz high-frequency range. The wave propagation technique proposes implementing the novel embedded SSUs to detect damage in the host structure. The numerical simulation is carried out with COMSOL multiphysics, and the received voltage signal is compared between the damaged and undamaged concrete beam with the applied actuation signal. A five-cycle sine burst modulated by a Hanning window is employed as the transient excitation signal. For numerical investigation, six cases are explored to better understand how the wave travels when a structural discontinuity is accounted for. The changes in the received signal during actuator–receiver mode in the damage state of the host structure are quantified using time of flight (TOF). Furthermore, the numerical studies are carried out by combining the EMI-WP technique, which implies synchronous activation of EMI-based measurements and wave stimulation. The fundamental idea is to implement EMI-WP to improve the effectiveness of SSU patches in detecting both near-field and far-field damage in structures. One SSU is used as an EMI admittance sensor for local damage identification. Meanwhile, the same EMI admittance sensor is used to acquire elastic waves generated by another SSU to monitor damages outside the EMI admittance sensor’s sensing area. Finally, the experimental validation is carried out to verify the proposed methodology. The results show that combining both techniques is an effective SHM method for detecting damage in concrete structures.

Swept frequency electrical impedance spectroscopy (EIS) can be used in conjunction with tethered bilayer lipid membranes to monitor the membrane permeability of ions in real-time (Deplazes et al. J Phys Chem Lett 11:6353-6358, 2020). Conductance readings, as determined by EIS, are a measure of the ability of ions to be transported across membranes. Recording the change in conductance as a function of cation concentration and a comparison between a range of cations permits conclusions to be made about the specificity of cation transport through pores. An estimate for upper pore size and cation selectivity of ion channels can be established using this method.

Nitric oxide and carbon monoxide diffusing capacities (DLNO and DLCO ) obey Fick's First Law of Diffusion and the basic principles of chemical kinetic theory. NO gas transfer is dominated by membrane diffusion (DM ), whereas CO transfer is limited by diffusion plus chemical reaction within the red cell. Marie Krogh, who pioneered the single-breath measurement of DLCO in 1915, believed that the combination of CO with red cell hemoglobin (Hb) was instantaneous. Roughton and colleagues subsequently showed, in vitro, that the reaction rate was finite, and prolonged in the presence of high P O 2 . Roughton and Forster (R-F) proposed that the resistance to transfer (1/DL ) was the sum of the membrane resistance (1/DM ) and (1/θVc), the red cell resistance (θ being the CO or NO conductance for blood uptake and Vc the capillary volume). From this R-F equation, DM for CO and Vc can be solved with simultaneous NO and CO inhalation. At near maximum exercise, DMCO and Vc for normal subjects were 88% and 79%, respectively, of morphometric values. The validity of these calculations depends on the values chosen for θ for CO and NO, and on the diffusivity of NO versus CO. Recent mathematical modeling suggests that θ for NO is "effectively" infinite because NO reacts only with Hb in the outer 0.1 μM of the red cell. An "infinite θNO " recalculation reduced DMCO to 53% and increased Vc to 95% of morphometric values. © 2020 American Physiological Society. Compr Physiol 10:73-97, 2020.

The precise detection of the toxic gas H 2 S requires reliable sensitivity and specificity of sensors even at minute concentrations of as low as 10 ppm, the value corresponding to typical exposure limits. CuO can be used for H 2 S dosimetry, based on the formation of conductive CuS and the concomitant significant increase in conductance. In theory, by elevated temperature the reaction is reversed and CuO is formed, ideally enabling repeated and long-term use of one sensor. Yet, the performance of CuO tends to drop upon cycling. Utilizing defined CuO nanorods we thoroughly elucidated the associated detrimental chemical changes directly on the sensors, by Raman and electron microscopy analysis of each step during sensing (CuO → CuS) and regeneration (CuS → CuO) cycles. We find the decrease in the sensing performance is mainly caused by the irreversible formation of CuSO 4 during regeneration. The findings allowed us to develop strategies to reduce CuSO 4 formation and thus to substantially maintain the sensing stability even for repeated cycles. We achieved CuO-based dosimeters possessing a response time of a few minutes only, even for 10 ppm H 2 S, and prolonged life-time.

The purpose of this study is to determine the effects of gamma (gamma)-ray irradiation on capacitance and conductance features of Al/Graphene/Al2O3/p-Si structure. Graphene has been grown on copper foil by the Chemical Vapor Deposition (CVD) method and transferred onto Al2O3/p-Si by the wet transfer method. After Al/Graphene/Al2O3/p-Si structure has been exposed to 30 kGy and 60 kGy gamma-ray irradiation, capacitance, and conductance measurements have been accomplished at 300 K. Electrical parameters have been compared before and after gamma-ray irradiation for 50 kHz and 500 kHz. These results have been confirmed that capacitance and conductance values have increased after gamma-ray irradiation and, have decreased when the radiation dose was increased from 30 kGy to 60 kGy. It has been observed that series resistance has decreased after 30 kGy radiation dose and has increased with increasing radiation dose.

The detection of CA 125 protein in buffer solution with a silicon-on-insulator (SOI)-based nanoribbon (NR) biosensor was experimentally demonstrated. In the biosensor, sensor chips, bearing an array of 12 nanoribbons (NRs) with n-type conductance, were employed. In the course of the analysis with the NR biosensor, the target protein was biospecifically captured onto the surface of the NRs, which was sensitized with covalently immobilized aptamers against CA 125. Atomic force microscopy (AFM) and mass spectrometry (MS) were employed in order to confirm the formation of the probe–target complexes on the NR surface. Via AFM and MS, the formation of aptamer–antigen complexes on the surface of SOI substrates with covalently immobilized aptamers against CA 125 was revealed, thus confirming the efficient immobilization of the aptamers onto the SOI surface. The biosensor signal, resulting from the biospecific interaction between CA 125 and the NR-immobilized aptamer probes, was shown to increase with an increase in the target protein concentration. The minimum detectable CA 125 concentration was as low as 1.5 × 10−17 M. Moreover, with the biosensor proposed herein, the detection of CA 125 in the plasma of ovarian cancer patients was demonstrated.

Perfluorocarboxylic acids (PFCAs) are an emerging class of persistent organic pollutants. During the fabrication process, it is unavoidable to form PFCA homologs or isomers which exhibit distinct occurrence, bioaccumulation, and toxicity. The precision measurement of PFCAs is therefore of significant importance. However, the existing characterization techniques, such as LC-MS/MS, cannot fully meet the requirement of isomer-specific analysis, largely due to the lack of authentic standards. Single-molecule sensors (SMSs) based on nanopore electrochemistry may be a feasible solution for PFCAs determination, thanks to their ultra-high spatiotemporal resolutions. Hence, as a first step, this work was to elucidate the influence of electrolyte concentration on the four most critical indicators of nanopore measurements, and furthermore, performance of nanopore SMSs. More specifically, three of the most representative short-chain PFCAs, perfluoropentanoic acid (PFPeA), perfluorohexanoic acid (PFHxA) and perfluoroheptanoic acid (PFHpA), were adopted as the target analytes, aerolysin nanopore was employed as the sensing interface, and 2, 3 and 4 M KCl solutions were used as electrolytes. It was found that, when the concentration of KCl solution increased from 2 to 4 M, the conductance of aerolysin nanopore increased almost linearly at a rate of 0.5 nS per molar KCl within the whole voltage range, the current blockade of PFPeA at −50 mV increased from 61.74 to 66.57% owing to the enhanced steric exclusion effect, the maximum dwell time was more than doubled from 14.5 to 31.5 ms, and the barrier limited capture rate increased by 8.3 times from 0.46 to 3.85 Hz. As a result, when using 4 M KCl as the electrolyte, over 90% of the PFPeA, PFHxA and PFHpA were accurately identified from a mixed sample, and the calculated limit of detection of PFPeA reached 320 nM, more than 24 times lower than in 2 M KCl. It was thus clear that tuning the electrolyte concentration was a simple but very effective approach to improve the performance of nanopore SMSs for PFCAs determination.

The electronic transmission of fifteen potential configurations of single-phenanthrene junction has been theoretically investigated. The structures include para-para, para-meta, and meta-meta combined with phenyl pendant group and substituted nitrogen atom. The results show that the para-meta, which offers a tunable antiresonance in the HOMO-LUMO gap, is the most suitable for synthesizing nano-device. The antiresonance is susceptible (unsusceptible) to the heteromotif location at site four (five). Hence, our paper presents the appropriate hetero-motif conditions—type and location— to synthesize molecular devices with the desired electronic conductance. The study also deepen the understanding of the molecular conductance by demonstrating the active and inactive sites to create and tune antiresonances. It finally introduces the essential impact of connectivity, quantum interference, and aromaticity in controlling the conductance of single-phenanthrene junction.

In this work, the effect of alkali treatments namely Na and RbF has been investigated on the potential induced degradation (PID) for CdS/CIGS solar cells. Four device types with variations in Na content and RbF post-deposition treatment (PDT) have been studied. Baseline Na devices (Type 1) show an average efficiency of ~18% which does not show an improvement with RbF-PDT (Type 1R) in this sample series. Low Na devices with and without RbF-PDT both show average efficiency of ~16% for this sample series. PID tests were conducted in dark at temperatures between RT- 85 °C under 1000 V applied between back of the soda-lime glass and the Mo contact. All device types show degradation due to increase in shunt conductance, which could be partially recovered by reversing the bias voltage polarity. Recovery of PID degradation is a temperature dependent phenomenon, wherein, higher recovery is observed at higher temperature. Preliminary results show low-Na devices recover to 80%, whereas, baseline Na devices recover to 50% of initial efficiency at 85 °C. RbF-PDT does not change the recovery of baseline Na devices, however, low-Na devices with RbF-PDT show recovery to only 25% of initial device efficiency.

A dual-channel flow-through microcalorimeter device is presented along with a non-contact precision method of temperature calibration. A microfluidic channel with a volume of ≈550 pL in a spiral layout was fabricated from low-stress nitride suspended over a cavity in a silicon substrate. The thin-film heater and resistive temperature detector (RTD) on the channel were defined by a patterned Ti layer. The device exhibited a rapid thermal response with the following thermal characteristics: a time constant of ≈10.5 ms, a heat conductance of $\approx 152~\mu ~\text{W}\,\cdot ~{\mathrm {K}}^{-{1}} $ and a heat capacitance of $\approx 1.6~\mu \text{J}\,\cdot {\mathrm {K}}^{-{1}} $ on average based on the measurements of nine separate units fabricated on the same wafer. Further, the melting curve analysis (MCA) of a double-stranded DNA was proposed as a non-contact method of microcalorimeter RTD calibration. The method revealed that the measurement by the RTD underestimates the temperature of the channel interior by an amount of nearly 15%, at ≈ 9 mW. At this dissipated power level, the method also revealed a spatial nonuniformity of ≈ ± 0.8 °C across the microcalorimeter. [2020-0173]

Development of chemical chaperones to solubilize membrane protein complexes in aqueous solutions has allowed for gas-phase analysis of their native-like assemblies, including rapid evaluation of stability and interacting partners. Characterization of protein primary sequence, however, has thus far been limited. Ultraviolet photodissociation (UVPD) generates a multitude of sequence ions for the E. coli ammonia channel (AmtB), provides improved localization of a possible post-translational modification of aquaporin Z (AqpZ), and surpasses previous reports of sequence coverage for mechanosensitive channel of large conductance (MscL). Variations in UVPD sequence ion abundance have been shown to correspond to structural changes induced upon some perturbation. Preliminary results are reported here for elucidating increased rigidity or flexibility of MscL when bound to various phospholipids.

In this work, we present a step-by-step workflow for the fabrication of 2D hexagonal boron nitride (h-BN) nanopores which are then used to sense holo-human serum transferrin (hSTf) protein at pH ∼8 under applied voltages ranging from +100 mV to +800 mV. 2D nanopores are often used for DNA, however, there is a great void in the literature for single-molecule protein sensing and this, to the best of our knowledge, is the first time where h-BN-a material with large band-gap, low dielectric constant, reduced parasitic capacitance and minimal charge transfer induced noise-is used for protein profiling. The corresponding ΔG (change in pore conductance due to analyte translocation) profiles showed a bimodal Gaussian distribution where the lower and higher ΔG distributions were attributed to (pseudo-) folded and unfolded conformations respectively. With increasing voltage, the voltage induced unfolding increased (evident by decrease in ΔG) and plateaued after ∼400 mV of applied voltage. From the ΔG versus voltage profile corresponding to the pseudo-folded state, we calculated the molecular radius of hSTf, and was found to be ∼3.1 nm which is in close concordance with the literature reported value of ∼3.25 nm.

It is well known that the physics of thermal management is quite challenging as electronic device sizes are miniaturized and new materials are developed. This study calculates the thermal interface conductance (TIC), thermal interface resistance (TIR) and thermal grain conductivity across GaAs(110)/GaAs(100) and GaAs/InAs interfaces using the reverse non-equilibrium molecular dynamics (RNEMD) technique. Data obtained showed that, at GaAs(110)/GaAs(100) the TIC increased from 0.912 x 10 -9 (W/K) to 1.433 x 10 -9 (W/K), the TIR decreased from 1.096 x 10 9 (K/W) to 0.697 x 10 9 (K/W) between 300 K and 1000 K, and the thermal grain conductivity increased from 7.47 (W/mK) to 15.52 (W/mK) and 7.48 (W/mK) to 80.71 (W/mK) between 15 A and 55 A at 300 K. At GaAs/InAs interface the TIC increased from 7.228 x -10 (W/K) to 14.498 x 10 -10 (W/K) and the TIR decreased from 0.138 x 10 10 (K/W) to 0.068 x 10 10 (K/W) between 300 K and 700 K, respectively. It was observed that, as temperature is increased the TIC and TIR for both materials change significantly. This trend is consistent with previous molecular dynamic studies of interface materials. Keywords : Interface conductance, thermal resistance, grain conductivity, temperature.

The impact of chemical reactions on the thermal boundary conductance (TBC) of Au/metal contact/β-Ga2O3 layered samples as a function of contact thickness is investigated using high-throughput thermoreflectance measurements. A maximum in TBC of 530 ± 40 (260 ± 25) MW/m2 K is discovered for a Cr (Ti) contact at a thickness of 2.5 (5) nm. There is no local maximum for a Ni contact, for which the TBC saturates at 410 ± 35 MW/m2 K for thicknesses greater than 3 nm. Relative to the Au/β-Ga2O3 interface, which has a TBC of 45 ± 7 MW/m2 K, these nanoscale contacts enhance TBC by factors of 6 to 12. The TBC maximum only exists for metals capable of forming oxides that are enthalpically favorable compared to β-Ga2O3. The formation of Cr2O3, via oxygen removal from the β-Ga2O3 substrate, is confirmed by TEM analysis. The reaction-formed oxide layer reduces the potential TBC and leads to the maximum, which is followed by a plateau at a lower value, as its thickness saturates due to passivation. Many advanced materials are prone to similar chemical reactions, impacting contact engineering and thermal management for a variety of applications.

N-benzyl-2-isonicotinoylhydrazine-1-carbothioamide (H3L) and its complexes with Co(II), Ni(II), Cu(II) and Zn(II) have been synthesized. The metal complexes have been characterized by elemental and thermal analyses, spectral studies of FT-IR, 1H and 13C NMR, ESR, MS, and UV-Visible, conductance and magnetic moments measurements. The free ligand exists in the keto-thione form, but it coordinates to the metal ion in the keto-thiol form. The 1:1 coordinated species, M(II)-H3L, are formed. The optical band gap (Eg) measurements indicated direct electronic transition and semi-conducting nature of the compounds. The cytotoxicity of H3L and its Zn(II) complex were tested against both HCT116 and HePG2. The ligand showed strong cytotoxicity against the two investigated cell lines, while Zn(II) complex exhibited moderate cytotoxic effect. The molecular docking on both colon and liver cancer proteins were studied and the data support the experimental results.

The paper describes the behavior of capacitance (C-V) and conductance (G/ω-V) versus voltage characteristics of Ag/SnO2/n-Si/Au metal-oxide-semiconductor (MOS) junction under dark and light condition. In addition, C-V of the junction is measured at room temperature for several frequencies. Ag/SnO2/n-Si/Au MOSjunction is fabricated with both spray pyrolysis at kept substrate temperature of 300 °C and thermal evaporation in high vacuum processes for the SnO2 layer and metallic contacts respectively. C-V curves present several peaks when SnO2/Si junction is illuminated with high light intensities. The peaks seem to Gaussian distribution within the reverse-forward bias voltage. Under dark room light and solar simulator conditions, the electrical measurements of junction are achieved presenting different behaviors. The carrier density, calculated from C-V measurements of metal oxide semiconductor junction as a function of light intensity, changes from 0.17 × 1017to 0.85 × 1017 cm−3 as a result of light intensity.

© 2019, Springer Science+Business Media, LLC, part of Springer Nature.Au/n-Si (MS) and Au/(SnO2-PVA)/n-Si (MPS) type SDs were manufactured at identical conditions for investigation of the (SnO2-PVA) organic/polymer interlayer effects on the electrical characteristics using voltage dependent current (I) and capacitance/conductance (C/G) data and compared each other. Rectifying ratio (RR) and the barrier height (BH) were found from forward bias ln(I)–V plots,. The values found are 2.5 × 102 and 0.57 eV for MS type SDs and 2 × 103 and 0.68 eV for MPS type SDs, respectively. The ideality factor (n), series resistance (Rs) and BH were also calculated from Cheung’s functions. They are agreement observed to be compatible with other results. The surface states versus (Ec−Ess) and Rs versus V curves were calculated by using the I–V data by using Roderick and Ohm’s law. The doping donor atoms (ND), Fermi energy (EF), BH of these SDs were also calculated from the reverse bias C−2–V data. While the calculated values of surface states and leakage current for the MPS is lower than Au/n-Si SD, RR is higher. Obtained results prove the use of a (SnO2-PVA) organic interlayer improved the performance of the Au/n-Si diodes.

Typically, utilization of small nanopipettes results in either high sensitivity or spatial resolution in modern nanoscience and nanotechnology. However, filling a nanopipette with a sub-10-nm pore diameter remains a significant challenge. Here, we introduce a thermally driven approach to filling sub-10-nm pipettes with batch production, regardless of their shape. A temperature gradient is applied to transport water vapor from the backside of nanopipettes to the tip region until bubbles are completely removed from this region. The electrical contact and pore size for filling nanopipettes are confirmed by current-voltage and transmission electron microscopy (TEM) measurements, respectively. In addition, we quantitatively compare the pore size between the TEM characterization and estimation on the basis of pore radius and conductance. The validity of this method provides a foundation for highly sensitive detection of single molecules and high spatial resolution imaging of nanostructures., 7 pages, 4 figures

Porous silicon (PSi) offers extremely attractive optical, electronic and biofunctional properties for the development of biosensors. In the present work, we have studied the step by step sandwich biofunctionalization cascade of a PSi platform by near ambient pressure X-ray photoelectron spectroscopy (NAP-XPS) and, in parallel, we have developed a three electrode PSi device sensitive to changes in surface conductance. Prior to the NAP-XPS characterization, the organosilanization with glycidyloxy-propyl-trimethoxy-silane, the bioconjugation, and the gold nanoparticle (AuNP) sensitization layer were monitored by spectroscopic ellipsometry. The NAP-XPS analysis revealed outstanding results: a) the NAP-XPS chamber allows detecting the pristine PSi with negligible adventitious carbon contamination, b) the single oxygen bonded carbon component of the Glycidyl group dominates the C1s core level after organosilanization, c) the good progress of the biofunctionalization/recognition is confirmed by the increase of the silica to silicon component ratio in the Si2p core level and, d) the N1s core level describes identical features from the presence of aminoacid sequences in the capture/detection steps. A FET sensing of a prostate specific antigen (PSA) marker was performed through conjugation with AuNPs. For a given concentration of PSA (and AuNPs) the conductance increased with the increase of the gate voltage. For a given gate voltage, the conductance was observed to increase for increasing concentration of PSA. This allowed proposing a calibration line for the biosensor, which is valid from a clinically relevant range of 0.1 ng/mL.

The influence of various doses of electron irradiation on the dielectric permeability and specific conductance of ternary nonlinear optical crystals of AgGaSe2 at various frequencies of the measuring field in a range of temperatures of 100–300 K is studied. It is found that the irradiation of single crystals leads to a decrease in the values of dielectric permeability and a significant increase in conductance. It is shown that dielectric permeability and conductance increase with the growth in temperature. It is found that the presence of several types of conductance is characteristic for the crystals of AgGaSe2. Substantial frequency dispersion of the dielectric properties of the studied crystals is found.

In this work, Au/n-Si (MS) structures with and without (Fe2O4-doped PVP) interlayer were prepared with the same conditions to see effects of organic layer on the electrical characteristics and conduction mechanisms. For this aim, I-V and Z-V measurements of them were carried out at room temperature. The saturation current (I-s), ideality factor (n), barrier height (phi(B)(I-V)), series (R-s) and shunt (R-sh) resistances, and rectifying rate (RR = I-F/I-R) of them were extracted from the I-V data as 2.90 x 10(-8) A, 1.699, 0.741 eV, 1.58 k ohm, 25.7 M ohm, 1.45 x 10(4) for MS and 2.30 x 10(-9) A, 1.634, 0.806 eV, 1.17 k ohm, 103 M ohm, 9.01 x 10(4) for MPS, respectively. The values of interface states (N-ss) were also extracted from the I-V data at forward bias by considering voltage dependent BH and n, and it is found that they increase from the mid-gap of semiconductor towards the conductance band. The values of doping atoms (N-D), Fermi-energy (E-F), and (phi(B)(C-V)) were also acquired from the C-2-V plots at reverse bias as 9.08 x 10(14) cm(-3), 0.258 eV, 0.914 eV for MS and 7.650 x 10(14) cm(-3), 0.263 eV, 0.981 eV, for MPS structure, respectively. It is clear that the (Fe2O4-PVP) interlayer leads to decreases in R-s, N-ss, leakage current and increase in rectifying rate (RR), R-sh and BH, so that it can used in place of the conventional oxide or insulator layer.

The voltage dependent surface states/traps (Nss) and their relaxation time () of the Al/CdZnO/p-Si (MIS) structure were investigated with admittance method using C-V-f and G/-V-f measurements in the frequency range of 5 kHz-1 MHz. Both the values of C and G/ were found as strong function of voltage and frequency and they increase with decreasing frequency almost for each voltage. The obtained higher values of C and G at the low frequencies are due to the presence of Nss located between CdZnO/p-Si interfaces. At low frequencies, the relaxation time of the charges at the traps is larger than the period (≥T) of the applied ac signal, so they can contribute to the measured C and G/ values. In addition, the presence of Nss causes a peak at the extracted parallel conductance (Gp/) versus Lnf curves of the structure. Thus, both the values of Nss and  were calculated from the peak value and its position, respectively. The values of Nss and  ranged from 1.65x1013 eV-1 cm-2, 31.4 s at 1.7 V and 1.39x1013 eV-1 cm-2, 9.18 s at 3 V, respectively. These values are very suitable for these structures at room temperature.