Effect Of Interfacial Layer Research Articles

ULTRAVIOLET ILLUMINATION RESPONSIVITY OF THE Au/n-Si DIODES WITH AND WITHOUT POLY (LINOLENIC ACID)-G-POLY (CAPROLACTONE)-G-POLY (T-BUTYL ACRYLATE) INTERFACIAL LAYER

Au/n-Si (MS) and Au/Poly (linolenic acid)-g-poly (caprolactone)-g-poly (t-butyl acrylate) (PLilPCLPtBA)/n-Si (MPS) diodes were fabricated to investigate the electrical and responsivity effects of interfacial layer on the diodes under ultra violet (UV) illumination. Electrospinning method was used for coating of the PLilPCLPtBA polymer layer on n-Si single crystal as nanofibers. Surface formation and nanofiber characteristics of the polymer layer were investigated by an electron microscope. The current-voltage ([Formula: see text]) measurements of the MS and MPS diodes were carried out in dark and under UV (365 nm) illumination conditions at room temperature. Basic electrical parameters of the diodes; such as reverse bias saturation current ([Formula: see text]), zero bias barrier height [Formula: see text], ideality factor ([Formula: see text]), series resistance ([Formula: see text]) and interface state density ([Formula: see text]) were extracted from the experimental [Formula: see text] measurements by thermionic emission and Norde equations. Also, power law of the photocurrents ([Formula: see text]) and responsivity ([Formula: see text]) behavior were obtained and given comparatively.

Insertion of HfO2 Seed/Dielectric Layer to the Ferroelectric HZO Films for Heightened Remanent Polarization in MFM Capacitors

This article highlights the role of HfO2 seed/dielectric insertion layers on the ferroelectric properties of hafnium zirconium oxide (HZO)-based metal-ferroelectric-metal (MFM) capacitors. Maximum remanent polarization ( ${P}_{r}$ ) of $22.1~\mu \text{C}$ /cm2 was achieved when HfO2 seed layer of critical thickness (10 A) was inserted at the bottom of HZO films. However, as the bottom HfO2 seed layer thickness increases from 10 to 200 A, the ${P}_{r}$ was found to decrease. The same critical thickness of HfO2 seed layer when inserted at top of the HZO films was found to give a maximum ${P}_{r}$ of $19.6~\mu \text{C}$ /cm2. The obtained ${P}_{r}$ in both the cases (bottom and top HfO2 seed layer) was found to be better than the reference HZO device ( $17.7~\mu \text{C}$ /cm2). Moreover, increased coercive field $({E}_{c})$ was noticed due to the HfO2 seed layer insertion (1.11 MV/cm for bottom HfO2 and 1.09 MV/cm for top HfO2) when compared with the reference device (1.04 MV/cm). Short pulse switching measurements were carried out on the as-fabricated capacitors, and an enhanced ${E}_{c}$ and interfacial capacitance was observed in case of devices with HfO2 seed layer. The crystal structures, and interfacial layer effect was keenly observed and analyzed for the HZO films with and without the seed layer using grazing incidence X-ray diffraction (GIXRD) and X-ray photoelectron spectroscopy (XPS), respectively. The HfO2 seed layer was found to result in higher o-phase formation, and facilitates the diffusion/migration of oxygen atoms from seed layer to the substrate or vice versa in the HZO capacitors giving rise to enhanced ferroelectricity.

A study of current‐voltage and capacitance‐voltage characteristics of Au/n‐GaAs and Au/GaN/n‐GaAs Schottky diodes in wide temperature range

AbstractIn this paper, a study of the effect of thin GaN interfacial layer (1 nm) on the electrical behavior of Au/n‐GaAs structure is investigated in wide temperature range 100 to 400 K, using Silvaco‐Atlas simulator. As a result, from I‐V characteristics, the series resistance R s is increased with decreasing temperature for Au/GaN/n‐GaAs structure, while it is remained almost constant for Au/n‐GaAs structure. The saturation current I s is decreased with decreasing temperature for both structures. The ideality factor n is increased, and the barrier height is decreased when temperature decreases, with important variation for Au/GaN/n‐GaAs structure. This abnormal behavior is due to the deviation of the dominant conduction mechanisms, from the thermionic emission TE current to the thermionic field emission TFE and the field emission FE. As well as, the Au/n‐GaAs structure shows a homogeneous of barrier height, while it is inhomogeneous for Au/GaN/n‐GaAs structure. In addition, from C‐V characteristics, the potential diffusion V d and the barrier height are increased with decreasing temperature for both structures, conversely to those obtained from the TE theory. These results confirm the deviation of the TE current to the TFE and FE currents with decreasing temperature for the Au/n‐GaAs and Au/GaN/n‐GaAs Schottky diodes.

Synergistic effect of interface layer and mechanical pressure for advanced Li metal anodes

Li metal anodes as one of promising anodes in next-generation batteries, face the challenges from infinite volume change and high reactivity to electrolytes that easily leads to unstable Li/electrolyte interface and unique dendrite growth of Li. Although mechanical pressure can effectively inhibit the dendrite growth of Li, it also increases the risk of short circuits, because Li metal easily grows into the separator under pressure. Here, an interface layer is introduced on Li metal to block this growth, using Li3P/LiCl as a model. Meanwhile, the dense and robust layer also reduce the side reactions between Li and electrolytes. With the helps from mechanical pressure and interface layer, this design exhibits the improved electrochemical performances, much better than that without pressure or without the layer. The full cells of Li3P/LiCl-coated Li//LiFePO4, show a capacity of 1.69 ​mAh cm−2 after 1000 cycles under pressure at 3.9 ​mA ​cm−2 with a capacity retention of 99.5% in carbonates. The results indicate the promising potential for the pressure effect to be used for advanced Li metal anodes.

Electrically detected magnetic resonance study of barium and nitric oxide treatments of 4H-SiC metal-oxide-semiconductor field-effect transistors

We report on the effects of barium interfacial layer (IL) deposition and nitric oxide (NO) anneals on interface/near-interface defects in 4H-SiC metal-oxide-semiconductor field-effect transistors utilizing electrically detected magnetic resonance (EDMR). The 4H-SiC/SiO2 interface has a large number of electrically active defects that reduce the effective channel mobility. Various passivation schemes have been utilized to decrease the interface defect density and thus increase mobility. Two passivation schemes of great interest are postoxidation annealing in nitric oxide (NO) and deposition of a barium interfacial layer (IL) before oxide growth. Our measurements compare the chemical nature of defects very near the 4H-SiC/SiO2 interface in devices utilizing both passivation schemes and nonpassivated devices. Both the NO anneal and the barium IL greatly reduce the interface region EDMR response, which corresponds to a large improvement in mobility. However, the EDMR response in devices subjected to the two passivation processes is somewhat different. We present results that suggest spin lattice relaxation times are longer in samples that received a barium IL than in samples with NO annealing; this result suggests a lower level of local strain within the vicinity of defects very near the 4H-SiC/SiO2 interface in barium treated samples over NO annealed samples.

Thickness Dependence of Ferroelectric and Optical Properties in Pb(Zr0.53Ti0.47)O3 Thin Films.

As a promising functional material, ferroelectric Pb(ZrxTi1−x)O3 (PZT) are widely used in many optical and electronic devices. Remarkably, as the film thickness decreases, the materials’ properties deviate gradually from those of solid materials. In this work, multilayered PZT thin films with different thicknesses are fabricated by Sol-Gel technique. The thickness effect on its microstructure, ferroelectric, and optical properties has been studied. It is found that the surface quality and the crystalline structure vary with the film thickness. Moreover, the increasing film thickness results in a significant increase in remnant polarization, due to the interfacial layer effect. Meanwhile, the dielectric loss and tunability are strongly dependent on thickness. In terms of optical properties, the refractive index of PZT films increase with the increasing thickness, and the photorefractive effect are also influenced by the thickness, which could all be related to the film density and photovoltaic effect. Besides, the band gap decreases as the film thickness increases. This work is significant for the application of PZT thin film in optical and optoelectronic devices.

Effect of interfacial layer on graphene structure in-situ grown on cemented carbide

In-situ spheroidal graphene film (SGF) may be a hopeful candidate of sensor matrix for space exploration. A poor understanding of the influence of interfacial layer on graphene structure restricts its benefit fulfillment. In this work, the SGF was in-situ grown on a cemented carbide substrate, and its influence on the graphene structure was investigated. An amorphous silicon carbide (a-SiC) layer was deposited on the carbide substrate by magnetron sputtering catalyzed by Co, a binding phase of carbide substrate, to form SGF under thermal annealing at 1000 °C. The influence of the interfacial layer on the graphene structure was investigated as a function of annealing time. As a result, the phase of the interfacial layer is a critical factor affecting the formation and structure of SGF. As the annealing time increases, the interfacial phase is transformed from CoSi to Co2Si, and then a pure Co2Si particles layer is formed. The C atoms, attached to the Co2Si particles, gather thereon and form the SGF. When the interfacial phase is a mixture of CoSi and Co2Si, multilayer graphene comprising many defects is formed. A bilayer graphene is obtained when the interfacial layer is composed of pure Co2Si.

A visco-hyperelastic softening model for predicting the strain rate effects of 3D-printed soft wavy interfacial layer

Strong strain rate effects were observed from uniaxial tension experiments on 3D printed specimens with soft wavy suture layer under the strain rates ranging from 10−3/s to 10−1/s. A stress-triaxiality-dependent visco-hyperelastic softening model was developed to predict the strain rate effects. The model was numerically implemented via ABAQUS/VUMAT. To characterize the model parameters under mixed mode I/II loading, uniaxial tension experiments were performed on a set of 3D printed scarf joint specimens under various strain rates. Also, finite element models of the 3D printed suture specimen were developed. By utilizing the visco-hyperelastic softening model for the soft interfacial layer, the strain-rate-dependent load-displacement relations and the failure mechanisms were accurately predicted from the numerical simulations. The results provide insights on how the strain rate and stress triaxiality jointly influence the damage initiation and evolution in a soft interfacial layer under in-plane mixed-mode loading.

Effect of an interface layer on thermal conductivity of polymer composites studied by the design of double-layered and triple-layered composites

The interfacial thermal resistance of polymer composites is a key factor affecting their thermal conductivity. But the interfacial thermal resistance might be influenced by many interface factors, such as defects, interface bonding strength, compatibility and the interface layer, which are difficult to be distinguished individually. The thickness of interfaces between fillers and polymers is in nanometer scale, leading to the research of effect of interface layer on thermal conductivity is very difficult. Herein, inspired by the differential calculus in mathematics, the effect of interface layer on thermal conductivity was studied through a design of double-layered and triple-layered alumina/silicone rubber composites and reflected by the through-plane thermal conductivity of the composites at the same filler loading. The top and bottom layers in the composites were used to represent a matrix and a filler, respectively. The middle layer in the triple-layered composites was assumed as an interface layer. The results showed that the presence of the interface layer could increase thermal conductivity when the thermal conductivity difference between the top and the bottom layers was high. A series model was used to simulate the dependence of thermal conductivity on the interface layer at triple-layered composites and real filler/polymer interface, respectively. This work could provide a new method to study the interface thermal resistance and promote the development of polymer composites with high thermal conductivity.

Effect of aluminum interfacial layer in a niobium oxide based resistive RAM

Resistive RAM (Random Access Memory) has good scalability with high switching speed and low operating voltage making it one of the promising emerging nonvolatile memory technologies. Interfacial layer between the electrode and metal-oxide interface in a Resistive RAM (ReRAM) could either enhance or deteriorate the switching performance of the device. In this study, we investigate the role of aluminum (Al) as an interfacial layer under the top electrode (TE) layer in a niobium oxide (Nb2O5) based ReRAM. We compare the Current-Voltage (I-V), Capacitance-Voltage (C-V) characteristics and endurance of the Nb2O5 based ReRAM with an Al interfacial layer below the tungsten (W) TE and a control sample without the Al interfacial layer to contrast the performance of each type. Additionally, we connect the tested device behavior with the enthalpy, entropy, and Gibb's free energy to illustrate that aluminum is an inefficient interfacial layer in the niobium oxide ReRAM.

Enhanced Photovoltaic Performance of Hybrid Solar Cells with a Calcium Interfacial Metal Electrode

A better understanding of how the interfacial layer influences charge carrier recombination would benefit the development of high-efficiency hybrid solar cells (HSCs). HSCs based on poly(3-hexylthiophene) (P3HT)/Si nanoparticles (Si NPs) with three identical electrodes were used as reference system to investigate the interfacial layer effects on device performance. The standard solar-grade silicon was produced using rice husk ash (RHA) as a biogenic source. The RHA was purified by using a low-cost and simple method followed by modified magnesiothermic reduction reaction to produce crystalline Si NPs. Prepared Si NPs as an acceptor material with different percentages of Ca interface layer metal electrodes on HSCs were studied. A highly conductive electrode was one of the important factors for enhancing the fill factor and power conversion efficiency (PCE). For fabrication and characterization of P3HT/Si NP HSCs with three identical thermally evaporated electrodes, Al (100 nm), Ca/Al (10 nm/90 nm), and Ca/Al (20 nm/80 nm) were used as top electrode. The device with a Ca/Al (10 nm/90 nm) electrode exhibited a lower recombination, while its efficiency was 20% and 10% higher than the devices with the Al (100 nm) and Ca/Al (20 nm/80 nm) electrodes, respectively.

Frequency effect on electrical and dielectric characteristics of In/Cu2ZnSnTe4/Si/Ag diode structure

In/Cu2ZnSnTe4/Si/Ag diode structure was fabricated by sputtering Cu2ZnSnTe4 (CZTTe) thin film layer on the Si layer with In front contact. The frequency dependent room temperature capacitance and conductance measurements were carried out to obtain detailed information of its electrical characteristics. Admittance spectra of the diode exhibited strong frequency dependence and the obtained values showed decreasing behavior with the increase in the applied frequency. The effect of interfacial film layer with series resistance values and density of interface states were investigated by taking into consideration of non-ideal electrical characteristics of the diode. The distribution profile of the interface states was extracted by Hill-Coleman and high–low frequency capacitance methods. As a function of frequency, they were in proportionality with the inverse of applied frequency. Dielectric constant and dielectric loss parameters were calculated from the maximum value of the diode capacitance at the strong accumulation region. The loss tangent showed a characteristic peak behavior at each frequency. Based on the time-dependent response of the interfacial charges to the applied ac field, the values of ac electrical conductivity and complex electric modulus were calculated and discussed as a function of frequency and bias voltage.

Double Interfacial Layers Effect on Optical Third-order Nonlinear Susceptibility, Refraction Index, and Absorption Coefficient of a Metal/ Dielectric Composite

We investigate the way of enhancing the optical third order susceptibility, the refractive index, and absorption coefficient of a composite media in which identical nonlinear nanospheres having double interfacial layer randomly embedded in the linear host medium. We observe two maxima peaks of the nonlinear properties. We also show that the effect of double interfacial layers on the third order susceptibility, the refractive index, and absorption coefficient depends on the volume fraction metal/ dielectric nanosphers and the nature of the double interfacial layers. Under appropriate condition (nature of the two interfacial layer) we found two maximum peaks of the nonlinear properties. We also compare with the same composite without interfacial layer and in the presence of single interfacial layer and our finding shows that because of additional interfacial layer the effective medium exhibit a better third-order susceptibility, refractive index, and absorption coefficient.

Determination of interface layer effects on magnetic properties of nanocomposite magnets and exchange coupling between magnetic entities

The interlayer plays a crucial role in improving the properties of many extremely important magnetic materials and devices by regulating the magnetic exchange coupling, while it is still not fully understood in a quantitative way. The main obstacle is that there is still no effective way to characterize quantitatively the ferromagnetic exchange coupling (FEC) strength after inserting the interlayer. In this paper, a rationally designed hard/interlayer/soft layered film is used to study the interlayer effects. It is demonstrated that the magnetic properties of nanocomposite magnets can be effectively enhanced through the modification of interface. Here a new concept, using the nucleation field Hns of soft phase as a “detector” to directly and quantitatively characterize/measure the FEC strength across interface and interlayer, is put forward. It is applied to address the dependence of FEC strength on thickness of nonmagnetic Cr and rare earth-rich phase interlayers. The detailed, distinguishing and typical decay behavior and length of FEC strength for these interlayers are successfully resolved for the first time. The new conception and experimental results get also strongly supported by the theoretical calculation. The nature or mechanism of exchange coupling between ferromagnetic grains or layers after adding the nonmagnetic interlayer is identified by using the hard/interlayer/soft layered film as a model system. Our results demonstrate the validity for characterizing/measuring quantitatively the FEC strength across different interlayer materials via strategy established in this work. It opens up new perspectives to gain insight into the interlayer property, and mechanism comprehension and high-performance design for magnetic materials and devices, such as permanent magnets, high-density magnetic recording media, advanced spin-orbit torque devices, etc.

The Investigation of Frequency and Voltage Dependence of Electrical Characteristics in Al/P3HT/p-Si (MPS) Structures

Abstract Metal-polymer-semiconductor (Al/P3HT/p-Si) structures have been fabricated and their electrical characteristics have been investigated using capacitance-voltage (C-V) and conductance-voltage (G/ω-V) measurements. These measurements were performed in the frequency and voltage range of 3 kHz-1MHz and ±5 V, respectively, at room temperature. The values of diffusion potential (VD), doping concentration of acceptor atoms (NA), Fermi energy level (EF) and barrier height (ФB) were obtained from the reverse bias C−2 vs V plot for each frequency by considering interface states (Nss), series resistance (Rs), and interfacial layer effects. All these parameters were found as strong functions of frequency and voltage. The values of both Nss and Rs decrease with increasing frequency. On the other hand, the value of Nss is prominent in the inversion and depletion regions at low frequency, but Rs and interfacial layer are prominent in the accumulation region at high frequency. Therefore, to see the effect of Rs both the C-V and G/ω-V plots were corrected for high frequencies. The voltage dependent profile of Nss and Rs were also obtained from Hill-Coleman and Nicollian-Brews method, respectively. Obtained results confirm that the values of Nss, Rs and interfacial layer are more effective on the impedance measurements

Mechanical and thermal shock properties of laminated ZrB2-SiC/SiCw ceramics

Laminated structure is an effective design to improve the fracture and ablation behaviors of ceramics in the high temperature fields. To investigate the effect of interface layer on the fracture manner of laminated ceramics, two laminated ZrB2-SiC/SiCw (LZSw) and ZrB2-SiC/SiCp (LZSp) ceramics were prepared by hot pressing with SiC whiskers and SiC powders as strong interface layers, respectively. The flexural strength and fracture toughness of LZSw ceramic reached 471 MPa and 15.9 MPa m1/2, respectively. This improved fracture toughness of the LZSw ceramic was mainly attributed to the introduction of SiC whiskers as the strong interface layer, which significantly prompted crack deflection and branching, increased crack propagation path and consumed more fracture energy during fracture process.

A theoretical model for the gas permeation prediction of nanotube-mixed matrix membranes: Unveiling the effect of interfacial layer

A new theoretical model was developed to predict the gas permeation behavior of mixed matrix membranes containing nanotubes (NT-MMMs). The proposed model was validated using a large number of CO2/N2 and CO2/CH4 separation data from the literature and a good agreement between the predicted and experimental data was observed. Most important, the proposed model explored the role of nanotube/matrix interface, by introducing the interfacial layer thickness parameter, lint. Moreover, an excellent correlation between the lint values and nanotube/matrix interfacial interactions, obtained from thermodynamic theories, provides a guideline to design the interface layer for fabricating the NT-MMMs with desired gas separation properties, without any need to using the adjustable parameter. Moreover, the presented procedure is a good alternative approach to expensive and tedious traditional methods to estimate the interfacial layer thickness in polymer composites.

A novel thermoplastic sizing containing graphene oxide functionalized with structural analogs of matrix for improving interfacial adhesion of CF/PES composites

A novel complex sizing containing PES and functionalized GO was prepared for improving interfacial adhesion of CF/PES composites. To achieve better dispersion of GO in sizing and improve the interfacial compatibility of composites, GO were covalently functionalized by 4, 4′-diaminodiphenyl sulfone (DDS) and 4, 4′-diaminodiphenyl ether, which have similar chemical structures to PES matrix. SEM, dynamic contact angle and TGA tests showed that functionalized GO were closely attached to the CF surface, and the surface energy as well as the thermal stability of CF were greatly increased. Among all the sizings, PES/GO-DDS exhibited the best reinforcing effect, revealing a significant increase of 74.1% in IFSS and 40.1% in ILSS as compared with un-sized CF. Notably, the variation trend of mechanical properties was accordant with the interfacial strength. Moreover, the interface enhancement mechanisms were proposed, the increased interfacial adhesion was benefited from the positive effect of interface layer.

Collective effect of hybrid Au-Ag nanoparticles and organic-inorganic cathode interfacial layers for high performance polymer solar cell

The cooperative effect of hybrid Au-Ag nanoparticles and organic-inorganic cathode interfacial layers to advance the power conversion efficiency (PCE) of regio regular (rr) P3HT:PCBM based polymer solar cells (PSCs) are systematically demonstrated. In this work initially, two types of plasmonic nanoparticles (NPs), namely, citrate stabilized gold (AuNPs) and silver (AgNPs) were separately synthesized and then physically blend together with three different volume ratio [AuNPs + AgNPs (25:75), AuNPs + AgNPs (50:50) and AuNPs + AgNPs (75:25)]. These three blended NP solutions were then mixed together in the PEDOT:PSS (20 v/v %) hole extraction layer (HEL) to form three new NPs doped HEL and their effect on the rr-P3HT:PCBM based PSCs were systematically analyzed. For dual organic-inorganic cathode interfacial layers, two organic hole blocking materials, BPhen and BCP were used for enhanced charge collection in combination with LiF:Al as conventional cathode electrode. The collective effect of hybrid NPs with the dual cathode interfacial layers was examined with two varying active polymer blends, rr-P3HT:PC61BM and rr-P3HT:PC71BM. It has been found that the PCE increases considerably for both the active blend systems, with PEDOT:PSS + [AuNPs:AgNPs (25:75)] + BCP:LiF:Al as the modified cathode electrode. This is due to suitable electronic energy level matching of BCP:LiF:Al and active blend with the excellent surface plasmon property of the AuNPs:AgNPs (25:75) in the UV–Visible region compared to AuNPs:AgNPs (50:50) and AuNPs:AgNPs (75:25). Devices having configuration PEDOT:PSS + [AuNPs:AgNPs (25:75)] as HEL, rr-P3HT:PC71BM as active blend and BCP:LiF:Al provided PCE, ɳmax = 5.71% with Jsc = 16.44 mA/cm2, Voc = 0.58 V, FF = 60% and device with rr-P3HT:PC61BM as active blend layer was showing as PCE, ɳmax = 5.31% with Jsc = 14.77 mA/cm2, Voc = 0.58 V and FF = 62% with the same PEDOT:PSS + [AuNPs:AgNPs (25:75)] layer and BCP:LiF:Al. These results conclusively described a very simple technique in which the cooperative effect of plasmonic hybrid metals nanoparticles and dual cathode interfacial layers outstandingly enrich the PCE and in general the complete nature of rr-P3HT:PCBM based PSCs.

Frequency and Voltage Dependence of Interface States and Series Resistance in Ti/Au/p-Si Diodes with 100 μm and 200 μm Diameter Fabricated by Photolithography

Ti/Au/p-Si diodes with the diameters of 100 and 200 μ m were fabricated by photolithographic technique. Capacitance–voltage (C–V) and conductance–voltage (G/w–V) characteristics of these diodes have been investigated by considering the series resistance (Rs) and interface states (Nss) effects. Experimental results show that the value of C and G/w in per area, with D1 (100 μ m) is lower than that of D2 (200 μ m) in depletion region but this behavior become reverse at accumulation region. Such behavior of C and G/w can be attributed to the special distribution of Nss at metal/semiconductor (M/S) interface, series resistance (Rs) of diode. The interface states density of the devices determined from high-low capacitance methods are presented for comparison. The voltage dependent profile of Rs was obtained for 100 kHz and 1 MHz. The observed anomalous peaks in C–V plots at 100 kHz were attributed to the effects of Rs, Nss and native interfacial layer. Experimental result show that the localizations of Nss at Ti/Au/p-Si interface, Rs and native interfacial layer have significant effects on the C–V and G/w–V characteristics of Ti/Au/p-Si diodes.