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The objective of this study is to produce polyvinyl alcohol (PVA)/carboxymethyl cellulose (CMC)/polypyrrole (PPy)/x wt% melanin blended polymers as future materials to utilize in the promising applications of electronic and storage energy fields. The structures and morphologies of the blends were investigated using X-ray diffraction and scanning electron microscopy techniques. The dielectric constant increased at 100 kHz from 55 to 8.6 × 104 as the host blend doped with 0.25 wt% melanin. The values of the energy density (U) were increased as the amount of melanin doping excess x = 0.1 wt% and it has the maximum value 5.41 J/m3 as x = 0.25 wt% at 100 Hz. The values of U for all blends increased as the temperature rose. Blend with x = 0.25 wt% has the highest ac conductivity. The conduction mechanisms in different blends were identified through the application of different theoretical models. The influence of the amount of melanin doping and temperatures on the real and imaginary parts of the electric impedance and the electric modulus, as well as the Nyquist curves was studied. Blend with x = 0.2 wt% has the highest dc conductivity (3.74 × 10–8 S m−1). All blends exhibit one or two activation energy values based on the temperature range and the amount of dopant. In conclusion, the outcomes obtained from the experiment demonstrated that the blended polymers consisting of PVA/CMC/PPy/x wt% melanin possess exceptional electrical properties, rendering them potentially valuable in the fields of energy storage and electronics. [ABSTRACT FROM AUTHOR]

This work focuses on the electrical transport and conduction mechanisms — inside a sprayed — made zinc oxide-on-p-type silicon junction device. A fabricated Al/ZnO/Si/Al heterojunction is characterized at 300 and 380 K in the dark. The aforementioned theories predict that the current density (J) is an exponential function of measured voltage (V) and work temperature (T). Exponential equations are linearized as a result of a current conduction mechanism (CCM) kind. Useful parameters like barrier height φ t of trap are extracted from the slope B. Ohmic and space charge limited current (SCLC) regimes inside are studied at 300 and 380 K recording a shift in exponent as a result of temperature. Fowler–Nordheim (FN) conduction mechanism inside Al/ZnO/Si/Al device is considered slope and ϕ b values are determined for two cited work temperatures. Our device presents a thermionic emission (TE) and exhibits an effect of temperature on slope and intercept values of (ln J T E /A* T 2 ) function. The Poole–Frenkel (PF) emission in terms of 1/V data are presented for 300 and 380 K. Besides, PF emission mechanism in terms of 1/ T 2 is exhibited and parameters are influenced by temperature. Behavior of conductance as a result of temperature is detailed and evidenced. [ABSTRACT FROM AUTHOR]

Herein, the effect of temperature on the switching characteristics and the conduction mechanism of the Ti/SiNx/Pt resistive random access memory device is investigated. The switching behavior of the device is investigated by comparing the I–V curves of the device in the temperature range of RT‐653 K. The temperature dependence of the current and the conduction mechanism of the device within RT‐463 K is investigated. It is found that the device exhibits good bipolar switching behavior in the temperature range of RT‐463 K, and the low resistance state (LRS) current and high resistance state (HRS) current show an increasing and then decreasing trend with increasing temperature. There is a stronger temperature dependence of the LRS current and the conduction mechanism from ohmic conduction to Schottky emission under LRS, which is attributed to the involvement of the reactive electrode Ti in the reaction at a certain temperature and the generation of a TiNx layer. Based on the above phenomenon, it is believed that not only the temperature affects the reliability of the device, but also the influence of reactive electrodes cannot be ignored. This article provides a reference for further preparation of SiNx‐based resistive random access memory devices with higher reliability and wider temperature usage range. [ABSTRACT FROM AUTHOR]

As electronic devices continue to develop, there is a growing demand for materials capable of supporting new physical properties, such as flexibility, stretchability, low‐temperature processability, applicability to large areas or ultra‐thin films, and operation at extremely low voltages. Metal oxide dielectrics, such as silicon dioxide, aluminum oxide, and hafnium oxide, offer excellent dielectric properties, but their ability to meet these new properties and the choice of substrate is limited. Therefore, a new dielectric material capable of providing stable dielectric properties with new functionalities is required. In this review, we briefly introduce the physical principles of dielectric materials and the recent trends of nonoxide dielectrics which satisfy requirements of new functionalities. We discussed various nonoxide dielectric materials of organic, self‐assembled mono/multilayers, electrolytes, two‐dimensional (2D) materials, and metal halides. Finally, we conclude with an outlook and challenges on dielectric materials for next‐generation micro‐ and macro‐electronics. [ABSTRACT FROM AUTHOR]

In this paper, the effect of atomic layer deposition (ALD)-derived Al2O3 passivation layers and annealing temperatures on the interfacial chemistry and transport properties of sputtering-deposited Er2O3 high-k gate dielectrics on Si substrate has been investigated. X-ray photoelectron spectroscopy (XPS) analyses have showed that the ALD-derived Al2O3 passivation layer remarkably prevents the formation of the low-k hydroxides generated by moisture absorption of the gate oxide and greatly optimizes the gate dielectric properties. Electrical performance measurements of metal oxide semiconductor (MOS) capacitors with different gate stack order have revealed that the lowest leakage current density of 4.57 × 10−9 A/cm2 and the smallest interfacial density of states (Dit) of 2.38 × 1012 cm−2 eV−1 have been achieved in the Al2O3/Er2O3/Si MOS capacitor, which can be attributed to the optimized interface chemistry. Further electrical measurements of annealed Al2O3/Er2O3/Si gate stacks at 450 °C have demonstrated superior dielectric properties with a leakage current density of 1.38 × 10−9 A/cm2. At the same, the leakage current conduction mechanism of MOS devices under various stack structures is systematically investigated. [ABSTRACT FROM AUTHOR]

The study is aimed at developing a technique for forming a structure with a Schottky barrier in the form of a mltilayer Al-Ag2S-ITO sandwich structure, which includes a condensate of colloidal Ag2S quantum dots passivated with thioglycolic acid molecules (Ag2S/TGA QDs). The spectral properties were studied using a USB2000+ spectrometer (Ocean Optics, USA) with a USB-DT light source (Ocean Optics, USA). Electrophysical and photoelectric properties of the structures were studied using a Keysight B1500A semiconductor device analyzer (Keysight tech, USA). The study of the temperature dependences of the properties in the temperature range from 300 to 360 K was carried out in a Shielded room (Faraday cage) placed in a muffle furnace. It was found that the conductivity of the Al-Ag2S-ITO structure is mostly governed by the Schottky barrier at the Al-condensed Ag2S QDs film junction. At the junction between the condensed Ag2S QDs film and Al, signs of the formation of a rectifying contact were found. Under the action of the optical radiation with a wavelength of 650 nm and less, which corresponds to the most probable exciton transition in the UV-Vis absorption of Ag2S/TGA QDs, an increase in the current was found for the negative branch of the J-V curve.

We reported the analysis and modeling of some conduction mechanisms in ultrathin aluminum oxide (Al2O3) films of 6 nm thickness, which are deposited by atomic layer deposition (ALD). This modeling included current-voltage measurements to metal-insulator-semiconductor (MIS) capacitors with gate electrode areas of 3.6 × 10−5 cm2 and 6.4 × 10−5 cm2 at room temperature. The modeling results showed the presence of ohmic conduction, Poole Frenkel emission, Schottky emission, and trap-assisted tunneling mechanisms through the Al2O3 layer. Based on extracted results, we measured a dielectric conductivity of 5 × 10−15 S/cm at low electric fields, a barrier height at oxide/semiconductor interface of 2 eV, and an energy trap level into bandgap with respect to the conduction band of 3.11 eV. These results could be affected by defect density related to oxygen vacancies, dangling bonds, fixed charges, or interface traps, which generate conduction mechanisms through and over the dielectric energy barrier. In addition, a current density model is developed by considering the sum of dominant conduction mechanisms and results based on the finite element method for electronic devices, achieving a good match with experimental data. [ABSTRACT FROM AUTHOR]

[Display omitted] • The coexistence of two different mechanisms has been observed at lower (tunneling) and higher (thermionic emission) applied bias. • The "Overlap Bias" has been defined as the bias value at which the two mechanisms have the same contribution. • The origin of the tunneling contribution has been attributed to the presence of structural defects in the AlGaN/GaN heterostructure. This paper investigates the forward conduction mechanism of W-based Schottky diodes on AlGaN/GaN heterostructures across a temperature range of 25–150 °C. Current-Voltage measurements carried out at different temperatures (I-V-T), allow to identify two coexisting mechanisms for charge transport. At lower bias the conduction mechanism is ruled by tunneling (TU), with a characteristic energy of E 00 = 75 meV extracted from the temperature dependence of the ideality factor. At higher bias the Thermionic Emission (TE) mechanism dominates, thus revealing the presence of an inhomogeneous barrier that increases from 0.77 to 0.94 eV with increasing the measurement temperature. An ideal barrier of 1.22 eV was extrapolated for a unitary ideality factor. Structural and electrical analyses performed at nanoscale level revealed the presence of a density of defects (dislocations) in the order of 4 × 109 cm−2. Conductive Atomic Force Microscopy (C-AFM) provided local electrical information, uncovering a significant correlation between the observed electrical characteristics and the nanoscale defect distribution. This detailed insight highlights the crucial role of the electrical characteristics of defects in influencing the tunneling current component at low bias, thereby providing valuable context for understanding the electrical behavior and performance of microscopic devices. [ABSTRACT FROM AUTHOR]

In this paper, ZnO-based composite (ZnO/Zn 2 SiO 4 /SiO 2 ) powders were prepared and investigated as a function of SiO 2 added amount. Indeed, the X-ray diffraction patterns (XRD) confirm the formation of ternary ZnO/Zn 2 SiO 4 /SiO 2 composites. The structural defects are shown to increase with the SiO 2 amount. In addition, the SEM observations reveal agglomerated and heterogenic grain shape distribution. Furthermore, dielectric properties were investigated as a function of SiO 2 added amount. The Nyquist plots are simulated by an electric circuit formed by a parallel distribution of resistance (R), capacitance (C), and a constant phase element (CPE), in all composites. Moreover, using the Jonscher's law, we demonstrate a change in conduction mechanism as a function of SiO 2 content. Indeed, for the 10 % SiO 2 doping, the conduction process is ensured by defects such as Zn interstitial and the oxygen vacancies, consistent with the Correlated Barrier Hopping (CBH) model. Whereas, for the 20 % SiO 2 doping, the conduction is dominated by grain boundaries contribution, according to the Non-Overlapping Small Polaron Tunneling (NSPT) model. Besides, the 10 % SiO 2 -doped composite exhibits localized relaxation process, while the 20 % SiO 2 -doped sample reveals simultaneously long-range and localized relaxations. These variations, caused by the increase of SiO 2 percent, can be explained by the influence of the growth of Zn 2 SiO 4 phase, and subsequently the development of further interfacial defects. Accordingly, the composites display capacitive behavior, high permittivity, and low dielectric losses, which make them good candidates for energy storage systems. [ABSTRACT FROM AUTHOR]

Ceramic samples based on the Ba 1- x Gd x TiO 3 system, where x = 0.001, 0.002, 0.003, 0.004 and 0.005, were prepared via the Pechini's chemical synthesis route. Structural properties, analyzed from X-ray diffraction and Rietveld refinement, revealed the formation of the pure ABO 3 perovskite structure with tetragonal symmetry (P4 mm) for all the studied compositions. Doping with Gd3+ promoted a reduction in the unit-cell volume, confirming the preferential substitution of the rare-earth cation at the A-site. The dielectric properties have been analyzed over a wide temperature and frequency range, revealing a significant contribution of the conduction mechanisms in the dielectric response of the studied ceramics. In fact, by using the Davidson-Cole formalism, the observed electrical behavior was found to be associated with relaxation processes related to intrinsic defects mobility promoted by a thermally-activated polaronic mechanism. The obtained values of the activation energy for the relaxation processes, estimated from the Arrhenius' law for the mean relaxation time, revealed a decrease from 0.29 up to 0.21 eV as the Gd-doping concentration increases, which suggests the conduction process to be associated with the polaronic effects due to the coexistence of Ti4+ and Ti3+ ions in the structure. Analysis from the conductivity formalism, by using the Jonscher's universal power-law, confirmed the polaron-type conduction mechanism for the dielectric dispersion, as suggested by the dielectric analysis, being the nature of the hopping mechanism governed by small polaron hopping (SPH) charge transport in the studied Ba 1– x Gd x TiO 3 ceramics. • Dielectric relaxation observed below T C is related to small polaron hopping conduction mechanism. • Thermally activated charge transport is ascribed to the charge compensation mechanism due to the heterovalent substitution. • The increase of the doping concentration promotes a decrease in the activation energy of the small polaron hopping mechanism. [ABSTRACT FROM AUTHOR]

The structural transformation, ferro-paraelectric and magnetic ordering induced dielectric phase transitions, multiferroic properties, relaxation and conduction mechanisms of (Gd 1- x Ba x)(Fe 1- x Ti x)O 3 ceramics with different compositions (x = 0.0–0.4) have systematically been investigated. The chemical route is adopted for material synthesis. Rietveld refinement reveals the structural transformation from orthorhombic to mixed phase (coexistence of orthorhombic and tetragonal phase) for x > 0.2. The analysis of the FESEM micrographs suggests a decrease in average grain size with the increase in BT in the composition. Dielectric anomalies are explained based on ferroelectric-paraelectric phase transition of BaTiO 3 , polarization induced by a spin reorientation, and antiferromagnetic ordering of GdFeO 3. The multiferroic properties of all the samples are studied from P-E, M-H, and magneto-electric plots. The improved magnetic properties in compositions x = 0.1–0.3, make them suitable candidates for spintronic devices. The maximum magneto-electric coupling coefficient of 4.77 mV/cm‧Oe in the composition x = 0.3, makes it very much suitable for application in magnetoelectric coupling devices. [ABSTRACT FROM AUTHOR]

Recently, NaNbO 3 (NN) has become a hot topic of current research due to its antiferroelectric energy storage properties, which demand that the ceramics withstand large applied electric fields. The breakdown strength is dependent on conduction properties, but there is limited research on the conduction mechanisms of NN. Here we report that A-site donor-doping of Bi3+ (Bi x Na 1-3x NbO 3) and B-site acceptor-doping of Mg2+ (NaNb 1-2/5y Mg y O 3) in NN lead to dramatic changes in the magnitude of the bulk conductivity (σ b) and the conduction mechanism of NN ceramics. Undoped NN exhibits mixed conduction behavior with an oxide ion transport number (t ion) of ∼0.44, and σ b of ∼10−6 S/cm at 600 °C. A low level of Bi3+ doping (x = 0.06) suppresses the NN mixed conduction mechanism to electron conduction (t ion ∼ 0), and the bulk conductivity increases significantly, σ b > 10−4 S/cm at 600 °C. On the other hand, Mg2+ doping (y = 0.06) samples mainly change the σ b , with the mixed ion/hole conduction (t ion ∼ 0.43) and σ b > 10−4 S/cm at 700 °C. The results show that the conductivity of NN increases and exhibits different conduction mechanisms with the doping of Bi3+ and Mg2+. Aliovalent doping is not beneficial to improving the insulation properties. Thus, this work provides theoretical guidance for the study of energy storage characteristics and the suppression of leakage behavior of high-temperature dielectric capacitors. [ABSTRACT FROM AUTHOR]

In this article, the dielectric properties of poly (9-vinylcarbazole) (PVK) and ferrocene-doped PVK thin films are studied. The thin films were grown by the isothermal solution casting technique. Dielectric properties of grown films were studied as function of ferrocene concentration, frequency, and temperature. The relative permittivity (ε′) is increased with increasing ferrocene percentage (~1%) due to the free charge carriers. The relative permittivity decreases for higher ferrocene percentage (~2%). However, the relative permittivity of PVK and ferrocene-doped PVK samples remains almost constant for studied temperature range (313–413 K). The frequency dependence of tan δ for all samples is studied. The frequency dependence of dielectric parameter exhibits frequency dispersion behavior, which suggests all types of polarization present in the lower frequency range. The loss tangent (tanδ) values are larger at higher temperatures in the low frequency region. However, the tan δ values at different temperatures are almost similar in the high frequency region. It is observed that the relative permittivity is maximum, dielectric loss is minimum, and AC conductivity is minimum for 1% ferrocene doped PVK as compared to pure PVK and 2% ferrocene doped PVK samples.

The impact of radiation on Si-based detectors garnered interest due to the observed degradation in their stability in high-radiation environments. In this study, we examined the effects of 3 MeV proton irradiation on both undoped and Al-doped n -Si diodes using I–V technique. The results revealed a decline in current trends for both types of diodes post-irradiation. This decrease was attributed to defects created by proton irradiation, which acted as recombination or trapping centres. However, the Al-doped n -Si diodes experienced a lesser decline in measured current, hinting at the radiation suppression effect of Al doping in Si. Additionally, Al-doped n -Si diodes displayed minimal changes in their diode parameters after irradiation, and their conduction mechanism remained unchanged. These results suggested that Al-doped n -Si diodes had superior stability compared to their undoped counterparts, implying that the presence of Al enhanced the diodes' resistance to radiation. The radiation suppression effect of Al seemed to stem from its ability to produce defects that improve Si's radiation-hardness, thereby mitigating the introduction of additional instability-causing defects during proton irradiation. Thus, incorporating Al was recommended for research aiming to improve the radiation resistance of Si. • Study explores 3 MeV proton impact on undoped and Al-doped n -Si diodes using I–V techniques. • Al-doped n -Si diodes show radiation suppression, with less current decline and minimal parameter changes after irradiation. • Al-doped n -Si diodes enhance Si-based detector radiation resistance by introducing stable defects through Al doping. [ABSTRACT FROM AUTHOR]

In this paper, the effect of atomic layer deposition (ALD)-derived Al2O3 passivation layers and annealing temperatures on the interfacial chemistry and transport properties of sputtering-deposited Er2O3 high-k gate dielectrics on Si substrate has been investigated. X-ray photoelectron spectroscopy (XPS) analyses have showed that the ALD-derived Al2O3 passivation layer remarkably prevents the formation of the low-k hydroxides generated by moisture absorption of the gate oxide and greatly optimizes the gate dielectric properties. Electrical performance measurements of metal oxide semiconductor (MOS) capacitors with different gate stack order have revealed that the lowest leakage current density of 4.57 × 10−9 A/cm2 and the smallest interfacial density of states (Dit) of 2.38 × 1012 cm−2 eV−1 have been achieved in the Al2O3/Er2O3/Si MOS capacitor, which can be attributed to the optimized interface chemistry. Further electrical measurements of annealed Al2O3/Er2O3/Si gate stacks at 450 °C have demonstrated superior dielectric properties with a leakage current density of 1.38 × 10−9 A/cm2. At the same, the leakage current conduction mechanism of MOS devices under various stack structures is systematically investigated.

High entropy perovskites LnCr 0.2 Mn 0.2 Fe 0.2 Co 0.2 Ni 0.2 O 3 ceramics were produced by solid-state reactions from oxides. The B-site chemical composition was fixed (Cr 0.2 Mn 0.2 Fe 0.2 Co 0.2 Ni 0.2) and A-site composition was varied by the rare-earth ions (Ln = Sm3+, Eu3+ and Gd3+). The entropy of B-sublattice mixing was 1.609R J/(mol*K). The dependences of the lattice parameters, microstructure features, and electrical properties were discussed as function of the A-site rare-earth ions. The correlation of the lattice parameters with the nature of the A-site rare earth ions was demonstrated. Impact of the rare-earth ions in A-site on microstructural parameters was observed. Charge conduction mechanisms were discussed in details for a wide range of temperatures. [ABSTRACT FROM AUTHOR]

Donor doping has always been the most simple, effective, and most common method to exploit outstanding performance of Bi4Ti3O12 (BIT) high‐temperature piezoceramics. Among various property parameters, the high‐temperature electrical insulation characteristic is a particularly important nature, which is an important guarantee for the steady and reliable operation of BIT‐based ceramics at high temperature. But, the electrical conduction mechanisms of donor‐doped BIT ceramics at high temperature are still unclear. Herein, the high‐temperature conduction mechanisms of Bi4Ti2.98(WNb)0.01O12 (BITWN) ceramics under different atmospheres are studied systematically and its high‐temperature conduction mechanisms are revealed for the first time. It is found that the high‐temperature conducting process of BITWN ceramics presents different conduction mechanisms under different atmospheres. BITWN exhibits n‐type and ionic conduction in the Ar atmosphere, whereas it is p‐type and ionic conduction in the O2 atmosphere, which is closely related to oxygen vacancy defects. The work subverts the prior cognition that the conduction mechanism of BIT‐based ceramics simply belongs to p‐type, and more importantly, provides the theoretical foundation for how to control the working atmosphere of donor‐doped BIT ceramics to obtain excellent electrical insulation in practical application. [ABSTRACT FROM AUTHOR]

Mixed halide perovskites are promising memristive materials because of their excellent electronic‐ionic properties. In this work, lead‐free Cs2AgBiBr6‐xClx (x=0, 0.2, 0.4, 0.6, 0.8, 1.0) double perovskite films were fabricated using a one‐step solution spin‐coating method in air. Moreover, the ITO/Cs2AgBiBr6‐xClx/Al sandwich‐like devices are fabricated to investigate the memristive behaviors. The present memristors exhibit nonvolatile and bipolar resistive switching behaviors without electroforming process. Interestingly, as the chloride content increases, the ON/OFF ratio of the device increases from 103 to 104, the average SET voltage and the RESET voltage decrease from −0.40 V to −0.21 V and from 1.55 V to 1.34 V, respectively. In addition, resistance states of devices can be maintained after 100 switching cycles and 104 s of reading. This study provides new possibility for the development of low‐power and environmentally friendly memristors. [ABSTRACT FROM AUTHOR]

In this study, nanocomposites ZnO-doped graphene+boron nitride nanosheets (BNNS) were produced, and their electrical and optical properties were investigated. The graphene+BN nano-hybrid layer used as a reinforcement element was synthesized using a liquid-phase exfoliation method. TEM images support the nanosheet's structure of the graphene and boron nitride. ZnO produced by sol-gel showed nanoscale spherical particles, while the commercial ZnO showed the micrometer scale with rod-like and hexagonal shapes. Composite materials were provided by reinforcing this reinforcement element into ZnO matrices, which were commercially available and were produced using the sol-gel procedure at different ratios. To compare the results, the BN nanosheets were synthesized using liquid-phase exfoliation. Using the same method, samples for comparison were produced by reinforcing these nano-hybrid sheets into the commercially available ZnO matrix and the sol-gel synthesized ZnO matrix. A limited increase was shown for the 0.1 wt% and 0.5 wt% in the nanocomposites' electrical conductivity ratios, along with the rise of the graphene + BN nano-hybrid sheet. The Eg values of the as-produced nanocomposites first decreased and then increased as the reinforcement ratio increased. The bandgap changing for all reinforcing types exhibits similar characters. The studied materials can be used in wide-scale electronic and optoelectronic devices, environmental, biomedical, and catalytic/photocatalytic activities. [ABSTRACT FROM AUTHOR]

This paper deals with the study of the physical properties of ZnO/ZnNb 2 O 6 /Nb 2 O 5 composite. X-ray diffraction (XRD) proves the coexistence of hexagonal ZnO, tetragonal Nb 2 O 5 and orthorhombic ZnNb 2 O 6. Scanning electron microscopy (SEM) observations reveals heterogenic distribution of grains with average size of about 456 nm. The dielectric measurements are performed in 20 Hz–1MHz frequency range between 150 °C and 350 °C. Theoretical fit demonstrates that the electric resistivity, associated to grains and grain boundaries, decreases as a function of temperature up to 275 °C. At 275 °C, the composite presents a semiconductor-metal transition, confirmed by the temperature-dependence of DC conductivity. Moreover, the AC conductivity variations suggest that the AC conduction mechanisms are explained by the Quantum-Mechanical Tunneling (QMT) model below 275 °C and the Non-Overlapping Small Polaron Tunneling (NSPT) one above 275 °C. Also, the activation energies, related to dielectric relaxation processes and DC conductivity, are almost equal: E a ~ 0.53eV in the interval 150 °C < T < 275 °C, and E a ~ −0.47eV for T > 275 °C. Moreover, the permittivity variations show the existence of interfacial Maxwell-Wagner-Sillars (MWS) and dipolar polarization. [ABSTRACT FROM AUTHOR]

We report on the influence of current density limits on phase transformation, density, and microstructure of Hydroxyapatite (HAp) subjected to flash sintering experiments. Arrhenius plots of the electrical conductivity during the constant heating rate experiments showed changes in the ionic conductivity mechanisms during the incubation time, contrasting behavior from other materials presented so far. Flash sintering also suppressed the formation of β-tricalcium phosphate, which occurs during conventional sintering. We report herein that low current density limits were able to successfully sinter dense HAp with minimal phase transformations under lower furnace temperature and significantly shorter time processing. [ABSTRACT FROM AUTHOR]

The electrical properties of transparent Li‐doped nickel oxide (NiO) epitaxial thin films grown on MgO (100) substrates using a sol–gel spin‐coating technique are investigated as to the Li concentration as determined by secondary ion mass spectroscopy. The epitaxial growth of the cubic Li‐doped NiO films with a cube‐on‐cube relationship is confirmed by X‐ray diffraction measurements. The electrical conductivity increases superlinearly with increasing Li concentration from 0.028 to 7.5 at%. The temperature dependence of the conductivity and the linear dependence of the activation energy on the mean distance between Li ions suggest that the conductivity can be explained within a hopping conduction framework. However, the significant Hall voltages observed in Hall effect measurements suggest the existence of nonhopping carriers in addition to hopping carriers. The Li concentration dependence of the conductivity cannot be well explained by the widely used model of small polaron hopping in which small polarons conduct through thermally activated hopping between nearest‐neighbor Ni sites. Instead, the observed dependence is well explained quantitatively by a model combining polaronic interacceptor hopping and nonhopping conductions. Polaronic interacceptor hopping conduction dominates for Li concentrations below 1 at%, whereas nonhopping conduction dominates for higher Li concentrations. [ABSTRACT FROM AUTHOR]

In this paper, the effect of atomic layer deposition-derived laminated interlayer on the interface chemistry and transport characteristics of sputtering-deposited Sm2O3/InP gate stacks have been investigated systematically. Based on X-ray photoelectron spectroscopy (XPS) measurements, it can be noted that ALD-derived Al2O3 interface passivation layer significantly prevents the appearance of substrate diffusion oxides and substantially optimizes gate dielectric performance. The leakage current experimental results confirm that the Sm2O3/Al2O3/InP stacked gate dielectric structure exhibits a lower leakage current density than the other samples, reaching a value of 2.87 × 10−6 A/cm2. In addition, conductivity analysis shows that high-quality metal oxide semiconductor capacitors based on Sm2O3/Al2O3/InP gate stacks have the lowest interfacial density of states (Dit) value of 1.05 × 1013 cm−2 eV−1. The conduction mechanisms of the InP-based MOS capacitors at low temperatures are not yet known, and to further explore the electron transport in InP-based MOS capacitors with different stacked gate dielectric structures, we placed samples for leakage current measurements at low varying temperatures (77–227 K). Based on the measurement results, Sm2O3/Al2O3/InP stacked gate dielectric is a promising candidate for InP-based metal oxide semiconductor field-effect-transistor devices (MOSFET) in the future.

This paper reports on the thin film characterization of a synthesized small molecular semiconductor N-butyl-N′-(6-hydroxyhexyl) perylene-3,4,9,10-tetracarboxylic acid diimide (N-BuHHPDI) and its potential use in Ag/N-BuHHPDI/PEDOT:PSS/p-Si heterojunction device. The device is fabricated using spin coating of a conducting polymer PEDOT:PSS on p-Si substrate followed by thermal deposition of a 100-nm-thin layer of N-BuHHPDI. To complete the fabrication of Ag/N-BuHHPDI/PEDOT:PSS/p-Si heterostructure, silver (Ag) is used as the top electrode. The device shows non-ohmic and asymmetrical current–voltage (I–V) characteristics in dark conditions at 25°C which confirm the successful formation of rectifying heterojunction. Various diode parameters such as ideality factor (n), barrier height (ϕb), series resistance (Rs) and charge carrier mobility across the interface of the heterojunction are measured from the I–V characteristics. The non-ideal behavior of the diode is correlated with the film morphology obtained by atomic force microscopy. Fourier transformed infrared spectroscopy is performed to confirm the successful preparation of N-BuHHPDI. The fluorescence lifetime (22 ns) of the N-BuHHPDI thin film is measured via fluorescence spectroscopy. Different charge conduction mechanisms including the dominant one are studied for the fabricated device. [ABSTRACT FROM AUTHOR]

We evaluate for high-voltage (HV) applications a series of metal/insulator/insulator/metal (MIIM) devices with relatively thick asymmetric Al2O3/Ta2O5 bilayer insulator barriers in which the Al2O3:Ta2O5 layer thickness ratio is varied from 1:1 to 1:9, with the thickness of the Al2O3 layer fixed at 30 nm. The impact of Ta2O5 to Al2O3 stack order and layer thickness ratio on current versus voltage asymmetry, reverse leakage, breakdown, and programable resistance ratio is investigated. Regions of operation are distinguished, and the responsible underlying dominant conduction mechanisms, including Schottky emission over the various barriers, ohmic conduction and Fowler–Nordheim tunneling through Al2O3, and defect-based Frenkel–Poole emission through Ta2O5 are identified. It was found that under positive bias, the low-resistance state in one-time programable usage is controlled by the thickness and properties of the Ta2O5 layer while the high-resistance state is determined by the thickness and properties of the Al2O3 layer. These results demonstrate that atomic layer deposition (ALD) bilayers are an effective way to engineer the electrical properties of HV metal-insulator-metal (MIM) devices. [ABSTRACT FROM AUTHOR]

The ac conductivity and dielectric response of bulk vanadyl 2,3-naphthalocyanine (VONPc) were investigated from 1 Hz to 106 Hz, at temperatures range from 288 K to 403 K. Thermal stability of the material was studied using thermogravimetric analysis (TGA). The structure phase was investigated using X-ray diffraction (XRD). The total conductivity was found to follow the universal power low σ(ω,T) = σ dc + Aωs. A temperature dependence and values greater than unity (super linear behavior) of the exponent factor s were found. Various types of activation energies were calculated and discussed. The calculated values of activation energies were found to be 0.27 eV, 0.23 eV and 0.21 eV for bulk conductivity (E b), dc conductivity (E dc) and relaxation process (E τ), respectively. The best conduction mechanism model that fit the observed exponent factors' values and behavior is the jump relaxation model as described by Funke. The real and the imaginary parts of the dielectric constant was observed to decrease as the frequency increases. The recorded value of the dielectric constant at high frequency is 3.3. • Ac conductivity and dielectric response of bulk vanadyl 2,3-naphthalocyanine (VONPc) were investigated using impedance spectroscopy technique. • Very good thermal stability up to 500 ᵒC was found. • Bulk conductivity, dc conductivity and the relaxation process activation energies were calculated. • Super linear frequency (s >1) and a temperature dependent of the frequency exponent factor. • The jump relaxation model as proposed by Funke was used to explain the conduction mechanism inside the material. [ABSTRACT FROM AUTHOR]

Metal oxide based core-shell (C-S) nanostructures have been studied for gas sensing applications to mitigate poor selectivity. When designing core-shell nanostructures with n-n, p-n and n-p junctions, an equalization of the Fermi level induces the formation of accumulation and depletion layers at the interface through charge, modifying the conduction channel. Mechanisms such as potential barrier carrier transport and surface depletion layer formation play important roles in enhancing the gas sensing performance of C-S nanostructures. Synthesis of C-S nanostructures is a multi-step process involving fabrication of core and shell layers. Selection of the core and the shell material is important as it would affect the properties of the heterojunction interface. Parameters such as the thickness of the shell layer, type of sensing material and working temperature have been studied for C-S nanostructure based gas sensors. However, less attention has been given to factors affecting the conduction mechanisms in C-S nanostructures. This review deals with understanding conduction mechanisms in one dimensional C-S nanostructures used for gas sensing applications, studying them based on synthesis methods used for fabrication and selection of materials used for core and shell layers. [ABSTRACT FROM AUTHOR]

The dynamic role of defects introduced through swift heavy ion (SHI) irradiation on structural, resistive switching (RS) behavior and charge conduction mechanisms of Y 0.95 Sr 0.05 MnO 3 (YSMO) manganite films are reported in the present communication. YSMO films were grown on single crystalline (100) n–type semiconducting Nb: SrTiO 3 (SNTO) substrates using pulsed laser deposition technique. All the films were irradiated by 200 MeV Ag+15 ions with different fluence to understand the effect of irradiation on the RS behavior of YSMO/SNTO films. In order to study the structural properties, θ–2θ X–ray diffraction measurement was performed at room temperature. To understand the RS behavior of presently studied YSMO/SNTO pristine and irradiated films, hysteretic current–voltage (I–V) characteristics were performed under the sweeping bias voltage cycles: 0 V → +10 V → 0 V → –10 V → 0 V across YSMO/SNTO interface at room temperature. In the present case, I–V curves show the p–n junction/diode like asymmetric behavior along with two different resistive states under both the positive and negative bias modes. Observed RS behavior has been attributed to the trapping–detrapping processes, modifications in the depletion region and movement of oxygen vacancies across the interface barrier between the YSMO films and SNTO substrates. Our main aim is to understand an active role of defects, strain modifications and local annealing or recrystallization effect across YSMO/SNTO interfaces under the effect of SHI irradiation for the modifications in the RS behavior. Thermionic emission mechanism has been identified to fit the different cycles of RS behavior of YSMO/SNTO pristine and all irradiated films to understand possible charge conduction processes across their interfaces. Time scale stability has been investigated for presently studied YSMO/SNTO films which suggest the improved memory abilities of the films irradiated with higher ion fluence. • High quality manganite films were deposited on SNTO substrates. • 200 MeV Ag+15 ions irradiation was performed with different ion fluence. • Modification in structural properties under the irradiation effect. • The defects induced resistive switching characteristics across YSMO–SNTO interface. [ABSTRACT FROM AUTHOR]

Abstract Effects of atmosphere, temperatures and duration time on the surface topography and the electrical conductivity of LiNbO 3 single crystals deposited with a 300-nm-thick layer of different metal films (Al, Mg and Zn) had been systematically investigated. LiNbO 3 samples covered with Al film annealed at 500 °C for 6 h in different atmosphere were firstly studied. There were a lot of small holes generated after the residual film cleaning. In addition, the surface roughness was enhanced with increasing pressure. Compared with areas that without metal Al coated, a sharp step was formed, especially the deep step of about 125 nm in 3%H 2 +Ar atmosphere. The I V curves reveal that the electrical conductivity of sample surface annealed at normal pressure was better than that in low vacuum. The current value was up to about 20 mA at 10 V in 3%H 2 +Ar, resulting in the conductivity significantly improved. Subsequently, samples deposited with different metal (Zn, Mg and Al, respectively) films annealed at 400 °C for 6 h in 3%H 2 +Ar were discussed. After wet etching, interestingly, a large number of nano-sized protrusions were formed on the surface. Both of samples coated with Mg and Zn films presented no obvious step depth, while a clear step about 13 nm was formed for Al-coated samples. The I V curves show that the surface conductivity of Zn-coated samples achieved the maximum of about 2.5 mA at 5 V among the three metals. Furthermore, Zn-coated samples annealed at different temperatures and holding time in 3%H 2 +Ar were also analyzed. After pickling, also, there were a lot of nanobulges appeared across the surface. With the temperatures keeping growth and the time extending, the nanobulges became much more compact and well-distributed. At the same time, the surface conductivity of samples would be gradually and effectively enhanced. The PL and XPS spectrums have indicated that more oxygen vacancies formed with increasing temperatures and holding time, resulting in the significant improvement in surface conductivity. The conduction mechanisms of sample surface can behave differently owing to the various annealing conditions. [ABSTRACT FROM AUTHOR]

In this work, electroluminescence in Metal-Insulator-Semiconductors (MIS) and Metal-Insulator-Metal (MIM)-type structures was studied. These structures were fabricated with single- and double-layer silicon-rich-oxide (SRO) films by means of Hot Filament Chemical Vapor Deposition (HFCVD), gold and indium tin oxide (ITO) were used on silicon and quartz substrates as a back and front contact, respectively. The thickness, refractive indices, and excess silicon of the SRO films were analyzed. The behavior of the MIS and MIM-type structures and the effects of the pristine current-voltage (I-V) curves with high and low conduction states are presented. The structures exhibit different conduction mechanisms as the Ohmic, Poole–Frenkel, Fowler–Nordheim, and Hopping that contribute to carrier transport in the SRO films. These conduction mechanisms are related to the electroluminescence spectra obtained from the MIS and MIM-like structures with SRO films. The electroluminescence present in these structures has shown bright dots in the low current of 36 uA with a voltage of −20 V to −50 V. However, when applied voltages greater than −67 V with 270 uA, a full area with uniform blue light emission is shown.

• ITO-Ag 2 S QDs film-Al structure forms photosensitive systems with the Schottky barrier. • Conductivity is mainly linked to Schottky barrier formed at the Al-Ag2S QDs junction. • Photosensitivity range coincides with ground state exciton transition in absorption. • It is possible to develop for photodiode structure, based on Ag2S/TGA, Ag2S/L-Cys QDs. In this work, we studied the electrophysical properties of condensates of colloidal Ag 2 S quantum dots (QDs), passivated with thiol-containing molecules (thioglycolic acid and L-cysteine) (further, Ag 2 S/TGA QDs and Ag 2 S/L-Cys QDs) on indium tin oxide (ITO) substrates. The temperature dependences of the electrical characteristics (conductivity) are analyzed in the temperature range from 300 to 360 K. Facts of the formation of the Schottky barrier structures is obtained. Activation energies of 0.2 eV (Ag 2 S/L-Cys QDs) and 0.66 eV (Ag 2 S/TGA QDs) were obtained by the use of linear approximations of current–voltage (I–V) characteristics in Arrhenius coordinates. It is shown that the conductivity of ITO - Ag 2 S QDs film - Al structure is mainly determined by the Schottky barrier that is formed at the Al-Ag 2 S QDs film junction. The rectifying contact is formed at the Ag 2 S film -Al junction due to the lower work function of Al. The I–V characteristics under the optical radiation action were analyzed for the studied sandwich structures. They turned out to be similar for Ag 2 S/TGA and Ag 2 S/L-Cys QDs. When a reverse or forward bias voltage is applied to a sandwich structure, in the case of the optical radiation action with a wavelength starting from the its value, corresponding to the most probable exciton transition in the QDs absorption the photocurrent is observed. The found difference (by an order of magnitude) in the photocurrent values of the sandwich structure, based on Ag 2 S/TGA QDs and Ag 2 S/L-Cys QDs is related to the smaller thickness of the Ag 2 S/TGA QDs film. [ABSTRACT FROM AUTHOR]

This study presents an algorithm for automated reliability analysis of embedded Metal-Insulator-Metal (MIM) capacitors with high-k dielectrics. With the proposed algorithm, Time-Dependent-Dielectric-Breakdown (TDDB) data of embedded capacitors of different physical dimensions measured at various stress conditions (temperature and electric field) can be analyzed in a uniform way based on a supervised learning approach. Instead of analyzing each influence parameter separately, the data is combined using automated linear regression, based on decision tree learning and thus defining a multi-dimensional plane. With this approach a simultaneous consideration of all affecting parameters and their interaction on the dataset can be achieved, while removing statistical outliers and extrapolating the reliability behavior of any failure percentage. To support the most common conduction mechanism related to the embedded ΜΙΜ capacitors, Poole-Frenkel emission, a new TDDB model with changed coordinate system is proposed. • Automated reliability analysis of MIM capacitors with high-k dielectrics • 4-D linear regression on Weibull distributions using Decision Tree Learning • Automated outlier detection and exclusion • Automated lifetime extrapolation of any failure rate • New extrapolation model for MIM capacitors with Poole-Frenkel conduction mechanism [ABSTRACT FROM AUTHOR]

The Ba0.5Sr0.5TiO3 (BST) thin films were deposited via radio frequency cathode sputtering on sapphire (α-Al2O3) and gadolinium gallium garnet (GGG) substrates. The effect of substrate material on the leakage current and mechanism of conductivity in BST stacks has been studied by tempera-ture dependent (300…400 K) current-voltage characteristics. Lower leakage currents of BST/α-Al2O3 thin films were achieved compared with that of BST/GGG thin films, especially in the high field re-gion. The conduction mechanism of the deposited films is found to be of Schottky emission type for a wide range of applied fields on both substrates. Schottky barrier height, effective Richardson con-stant, effective mass of conduction electrons in dielectric, and dynamic dielectric constant within the bounds of thermionic emission theory were found.

Printing of electrical circuits and interconnects using isotropic conductive adhesives (ICAs) is of great interest due to their low-temperature processing and compatibility with substrates for applications in sensors, healthcare, and flexible devices. As a lower cost alternative to silver (Ag), copper (Cu)-filled ICAs are desirable but limited by the formation of high-resistivity Cu surface oxides. To overcome this limitation, self-assembled monolayers (SAMs) of octadecanethiol (ODT) have been demonstrated to reduce the oxidation of micrometer-scale Cu powder particles for use in ICAs. However, the deposition and function of the SAM require further investigation, as described in this paper. As part of this work, the stages of the SAM deposition process, which included etching with hydrochloric acid to remove pre-existing oxides, were studied using X-ray photoelectron spectroscopy (XPS), which showed low levels of subsequent Cu oxidation when ODT coated. The treated Cu powders were combined with one- or two-part epoxy resins to make Cu-ICAs, and the effect of the Cu surface condition and weight loading on electrical conductivity was examined. When thermally cured in an inert argon atmosphere, ICAs filled with Cu protected by ODT achieved electrical conductivity up to 20 × 10 5 S·m -1 , comparable to Ag-ICAs, and were used to make a functional circuit. To understand the function of the SAM in these Cu-ICAs, scanning and transmission electron microscopy were used to examine the internal micro- and nano-structures along with the elemental distribution at the interfaces within sections taken from cured samples. Sulfur (S), indicative of the ODT, was still detected at the internal polymer-metal interface after curing, and particle-to-particle contacts were also examined. XPS also identified S on the surface of cured Cu-ICAs even after thermal treatment. Based on the observations, electrical contact and conduction mechanisms for these Cu-filled ICAs are proposed and discussed.

Abstract The time evolutions of transient current data for As 2 Te 3 (In) thin films were measured at different electric fields for the dc voltages of 0.001 V, 0.002 V, 0.005 V, 0.01 V, 0.1 V, 0.5 V and 1 V at room temperature (296 K). Transient current was analyzed by means of time series analysis in order to identify different conduction regimes. The maximal Lyapunov exponents for the transient currents were calculated. Positive maximal Lyapunov exponents reflected electric field dependence with positive Lyapunov exponents. Existence of a positive Lyapunov exponent means sensitive dependence on initial conditions and As 2 Te 3 (In) is known to have memory effects hence different initial conditions for each dc current measurement. Detrended Fluctuation Analysis was utilized to characterize the behavior of dc current time series which is invariant to initial conditions. Detrended Fluctuation Analysis identified three different conduction regimes with multiple conduction mechanisms. Highlights • DFA identifies three district conduction regime in As 2 Te 3 (In). • DFA clarifies competing conduction mechanisms in each regime. • DFA reveals the long range correlation properties. • The existence of an interplay between the particular mechanisms. • A crossover indicates different mechanisms with different time scales. [ABSTRACT FROM AUTHOR]

Yttria tetragonal zirconia polycrystalline (3YTZP) ceramic composites with 5, 10 and 20 vol% graphene nanoplatelets (GNPs) were prepared by spark plasma sintering (SPS) and their electrical conductivity as a function of temperature was characterized. The composites exhibit anisotropic microstructures so the electrical conductivity studies were carried out in two directions: perpendicular (σ ⊥ ) and parallel ( σ || ) to the SPS pressing axis. The composites with 5 and 10 GNP vol% showed high electrical anisotropy, whereas the composite with 20 GNP vol% exhibited nearly isotropic electrical behavior. σ ⊥ shows metallic-type behavior in the composites with 10 and 20 vol% GNP revealing that charge transport takes place through defect-free GNPs. For the composite with 5 vol% GNP the observed semiconductor-type behavior was explained by a two dimensional variable range hopping mechanism. σ || shows metallic-type conductivity in the composite with 20 GNP vol% and positive dσ || /dT slope in the composites with 5 and 10 GNP vol%. [ABSTRACT FROM AUTHOR]

This study investigated the nonvolatile memory characteristics of devices fabricated with PMMA embedding composite of graphene and molybdenum disulphide, which were employed as charge-trapping centres. X-ray diffraction measurements, Scanning and transmission electron microscope image analysis along with other characterisation techniques were performed for the assessment of the nature of graphene MoS 2 hybrid system. Bistable I-V characteristics of the device revealed stable and rewritable memory effect. A significantly high resistance ratio > 10 4 (R off /R on ) was observed even after 10 days. The reliability and reproducibility of the devices were tested for 10 4 cycles. The conduction mechanisms of the fabricated nanocomposite based memory cell were discussed on the basis of experimental data using a charge trapping–detrapping mechanism in the graphene MoS 2 hybrid. Owing to the increasing interest in the flexible electronics, bending tests were carried out on the devices fabricated on PET substrates. Bendability test at various bending diameters (40-5 mm) for 100 cycles was carried out to show the mechanical robustness of the device. [ABSTRACT FROM AUTHOR]

Purpose Al2O3 used as gate dielectric enables exploitation of higher electric field capacity of SiC, improving capacitive coupling and memory retention in flash memories. Passivation of traps at interface and in bulk which causes serious threat is necessary for better performance. The purpose of this paper is to investigate the effect of post-deposition rapid thermal annealing (PDA) and post-metallization annealing (PMA) on the structural and electrical characteristics of Pd/Al2O3/6H-SiC capacitors.Design/methodology/approach Al2O3 film is deposited by ALD; PDA is performed by rapid thermal annealing (RTA) in N2 at 900°C for 1 min and PMA in forming gas for 10 and 40 min. X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) measurements data are studied in addition to capacitance-voltage (C-V) and current-voltage (I-V) characteristics for the fabricated Pd/Al2O3/SiC capacitors. Conduction mechanism contributing to the gate leakage current is extracted for the entire range of gate electric field.Findings RTA forms aluminum silicide at the interface causing an increase in the density of the interface states and gate leakage current for devices with an annealed film, when compared with an as-deposited film. One order improvement in leakage current has been observed for the devices with RTA, after subjecting to PMA for 40 min, compared with those devices for which PMA was carried out for 10 min. Whereas, no improvement in leakage current has been observed for the devices on as-deposited film, even after subjecting to PMA for 40 min. Conduction mechanisms contributing to gate leakage current are extracted for the investigated Al2O3/SiC capacitors and are found to be trapfilled limit process at low-field regions; trapassisted tunneling in the mid-field regions and Fowler–Nordheim (FN) tunneling are dominating in high-field regions.Originality/value The effect of PDA and PMA on the structural and electrical characteristics of Pd/Al2O3/SiC capacitors suitable for flash memory applications is investigated in this paper. [ABSTRACT FROM AUTHOR]

Lead sulfide nanocrystal films, comprising of well faceted 350 nm cubic-nanocrystals are tailored by ion-flux controlled chemical bath deposition at 50 °C to 80 °C bath temperatures. These possess compact (111) oriented nanocubic morphology and exhibit significantly improved electrical and opto-electronic properties as necessary for emerging next generation solar energy conversion applications. All films are of p -type nature and concurrently possess high carrier mobility ( µ ), high hole concentration ( p ) and low electrical resistivity ( ρ ) at room temperature. In particular, for films grown at 75 °C, high values of µ = 29.3 cm 2 V –1 s –1 , p = 8.1×10 17 cm –3 and ρ = 0.26 Ω cm are observed on the same nanocubic film. At high temperatures (T > 150 K), the charge transport is governed by thermally activated band conduction and nearest-neighbour hopping conduction. However, at lower temperatures (T < 150 K), both Mott variable-range hopping (VRH) and Efros–Shklovskii (ES) VRH type hopping are prevalent. PbS films grown at 75 °C have the lowest thermal activation energy. The distinct crossover from Mott-VRH to ES-VRH conduction process is observed at ~ 80 K. The observed decrease in Mott temperature with increase in bath temperature has been attributed to the lesser defects and enhanced density of states at Fermi level, which suggest the reduction in activation energy of the films beneficial for improved cell performance. Prevalence of conduction mechanisms is correlated with growth process. [ABSTRACT FROM AUTHOR]

We demonstrated the feasibility to fabricate two-terminal non-volatile-memory (NVM) devices using pulsed radio frequency (rf) plasma polymerization and simple solution route. The two-terminal NVM devices were fabricated based on a metal-insulator-metal structure consisting of graphene quantum dots (GQDs) embedded in hexamethyldisiloxane dielectric layers. The charge trapping layer, GQDs and the top contacts were formed by spin coating and spray coating methods. Whereas, the dielectric layers were deposited using pulsed rf plasma polymerization. The current-voltage curves showed a bistable current behavior with the presence of hysteresis window. The fabricated NVM memory devices were reprogrammable when the endurance test was performed and stable up to 1 × 10 4 s cycles with a distinct ON/OFF ratio of 10 4 . Based on the obtained I-V characteristics, Schottky emission, Poole-Frenkel emission, trapped-charge limited-current and space-charge-limited current were proposed as the dominant conduction mechanisms for the fabricated NVM devices. [ABSTRACT FROM AUTHOR]

The composites based on single-walled carbon nanotubes (single-walled CNTs or SWCNTs) embedded in porous matrices with different structures were prepared and studied by using the impedance spectroscopy. The contributions of intra-CNT and inter-CNT conduction mechanisms in the composites were evaluated at various contents of SWCNTs from the analysis of their impedance spectra. The electrical percolation thresholds for the composites studied were determined by taking into account the tunneling through the potential barriers between SWCNTs. [ABSTRACT FROM AUTHOR]

We fabricated graphene-based non-volatile memory device by solution-processed route in this work. Thermally reduced graphene oxide (rGO) on quartz substrate prepared in the ambient of acetylene/hydrogen plasma treatment was used as bottom conductive electrode to replace the commonly-used bottom conductive indium-tin-oxide layer. The morphology of the rGO film was characterized and used for device fabrication. The device was fabricated in the simple structure of silver nanowires/nanocomposite/rGO/quartz and the nanocomposite was prepared by mixing the graphene quantum dots and graphene oxide in ethanol. Current-voltage ( I – V ) measurement of the fabricated device shows current bistablity with the similar behavior as write-once-read-many-times (WORM) memory device. The ON/OFF ratio of the current bistability for the devices was as large as 1 × 10 3 with retention stability up to 1 × 10 4 s. The direct tunnelling, trapped-charge limited-current, and Ohmic conduction were proposed as dominant conduction mechanisms through the fabricated NVM devices based on the obtained I – V characteristics. [ABSTRACT FROM AUTHOR]

Memristive devices and materials are extensively studied as they offer diverse properties and applications in digital, analog and bio-inspired circuits. In this paper, we present an important class of memristors, multiferroic memristors, which are composed of multiferroic multilayer BaTiO/NiFeO/BaTiO thin films, fabricated by a spin-coating deposition technique on platinized Si wafers. This cost-effective device shows symmetric and reproducible current-voltage characteristics for the actuating voltage amplitude of ±10 V. The origin of the conduction mechanism was investigated by measuring the electrical response in different voltage and temperature conditions. The results indicate the existence of two mechanisms: thermionic emission and Fowler-Nordheim tunnelling, which alternate with actuating voltage amplitude and operating temperature. [ABSTRACT FROM AUTHOR]