Advanced Electronic Applications Research Articles

Influence of R2O3 (R=Al, La, Y) on the structure and properties of strontium borosilicate glasses

The influence of R2O3 (R=Al, La, Y) on the structure, thermal, and some physical properties of strontium borosilicate glasses have been investigated by differential thermal analysis, X-ray diffraction, and Fourier-transform infrared spectroscopy. Fourier-transform infrared spectroscopy results showed that the network of the investigated glasses consists mainly of BO3, BO4, and SiO4 structural units. The influence of R2O3 on the properties of strontium borosilicate glasses depends on the structural role of R3+ ions. The experimental results suggest that Al3+ ions act as intermediate in the investigated composition range, while La3+ and Y3+ ions act as modifiers and depolymerize the glass network. The obtained results showed that the glass transition temperature (610–6600С), dilatometric softening temperature (640–6750С), and molar volume (25.03–29.22 cm3/mol) values of the investigated glasses were increased with equimolar substitution of SrO by R2O3. The thermal expansion coefficient (6.8–9.5 ppm/K) of the investigated glasses was found to decrease with increasing the R2O3 content. The obtained results showed that the density (3.03–3.68 g/cm3) values of the investigated glasses were increased with increasing the Y2O3 and La2O3 content and decreased with increasing the Al2O3 content. The tendency to crystallize is higher in glasses containing La2O3 compared to glasses containing Y2O3 or Al2O3. The results obtained in this study indicate that the investigated glasses can be potential candidates for advanced aerospace and electronic applications as heat-resistant electrical insulating glass- and glass-ceramic-to-metal seals and coatings.

Effects of metal layers on chemical vapor deposition of diamond films

Abstract Diamond is recognized as one of the most promising wide bandgap materials for advanced electronic applications. However, for many practical uses, hybrid diamond growth combining metal electrodes is often demanded. Here, we present the influence of thin metal (Ni, Ir, Au) layers on diamond growth by microwave plasma chemical vapor deposition (MWCVD) employing two different concepts. In the first concept, a flat substrate (GaN) was initially coated with a thin metal layer, then exposed to the diamond MWCVD process. In the second concept, the thin diamond film was firstly formed, then it was overcoated with the metal layer and finally, once again exposed to the diamond MWCVD. It should be mentioned that this concept allows the implementation of the metal electrode into the diamond bulk. It was confirmed that the Ni thin films (15 nm) hinder the formation of diamond crystals resulting in the formation of an amorphous carbon layer. Contrary to this finding, the Ir layer resulted in a successful overgrowth by the fully closed diamond film. However, by employing concept 2 (ie hybrid diamond/metal/diamond composite), the thin Ir layer was found to be unstable and transferred into the isolated clusters, which were overgrown by the diamond film. Using the Au/Ir (30/15 nm) bilayer system stabilized the metallization and no diamond growth was observed on the metal layer.

Conversion of n-type to p-type conductivity in ZnO by incorporation of Ag and Ag-Li

Elemental doping is an efficient strategy to modulate different properties of semiconductors. Conversion from n-type to p-type and band gap modulation of ZnO are investigated by theoretical and experimental pathways studies. The structural, electronic and optical properties of undoped, Ag and Ag-Li doped ZnO are studied in the framework of density functional theory (DFT). The value of direct band gap is found to be ~ 0.730, 0.440, 0.274, and 0.870 eV for undoped, Ag = 6.25% and 12.5% doped, and Ag= 6.25, Li= 6.25% co-doped ZnO, respectively. Acceptor levels are created at the top of the valence band and above the Fermi level in Ag and Ag-Li doped ZnO which reveals that Ag and Ag-Li are promising dopants for generating p-type ZnO. Importantly, a remarkable change in photoconductivity and optical properties are observed. The surface morphology of the spray deposited Zn100-xAgxO (x = 0.0–20%) and Zn100-x-yAgxLiyO (x = 5, y = 0.0–10%) thin films are changed with Ag and Ag-Li contents. The XRD patterns confirmed the hexagonal structure of all the deposited films. The band gap decreases from 3.27 to 3.08 eV (for Ag doped ZnO) and increases from 3.16 to 3.38 eV for Ag-Li doping ZnO, respectively. The dielectric constants and photoconductivity spectra support the formation of p-type conductivity of Zn100-xAgxO and Zn100-x-yAgxLiyO, which are in good agreement with the available theoretical and experimental reports. Thus, the studies performed in this work help us to understand the Ag and Ag-Li doping mechanism in ZnO; opening up possible directions toward the fabrication of p-type ZnO for advanced electronic and optoelectronic applications.

Synthesis and properties of cycloaliphatic diepoxides containing fluorinated linker

AbstractCycloaliphatic diepoxides, CAEs, are well known for their better thermal, chemical and optical properties, compared with the glycidyl ether type epoxides. However, the shortages including low moisture resistance, and high reflective index or high dielectric constant limit their use for the emerging advanced optical and electronic applications, In this work, we have synthesized two new cycloaliphatic diepoxides containing different fluorinated linkers (2,2′‐((2,2,3,3‐tetrafluorobutane‐1,4‐diyl)bis(oxy))bis(7‐oxabicyclo[4.1.0]heptane) (TCE) and 2,2′‐((2,2,3,3,4,4,5,5‐octafluorohexane‐1,6‐diyl)bis(oxy))bis(7‐oxabicyclo[4.1.0]heptane) (OCE) and characterized their chemical structures using 1H NMR, 19F NMR, and Fourier transform infrared spectroscopy. We have cured these two fluorine‐containing CAEs, using hexahydro‐4‐methylphthalic anhydride (HMPA) and compared them with a commercial CAE, 3,4‐epoxycyclohexylmethyl‐3,4‐epoxycyclohexanecarboxylate (ERL‐4221) under the same condition. Compared to the cured ERL‐4221 (C‐ERL‐4221), the cured fluorinated CAEs (C‐OCE, C‐TCE) have much better water resistances (saturated water absorption after 6 days in water: 0.70%, 1.72%, and 2.83%, for C‐OCE, C‐TCE, and C‐ERL‐4221, respectively) and lower dielectric constant (Dk) (Dk: 2.54–2.44 and 2.78–2.66 vs. 4.01–4.00 @ 1 Hz‐5 MHz), and similar thermal stability (the statistical heat‐resistant index [Ts]: 169°C, 175°C vs. 175.5°C), although their glass transition temperature (Tg) and storage moduli are lower (Tg: 136°C, 171°C vs. 250°C; moduli: 0.56GPa, 1.25GPa vs. 1.38GPa). These results reveal that fluorine atoms on the linkers effectively reduce dielectric constant and improve hydrophobicity and wettability, providing new insights into the design of fluorine‐containing cycloaliphatic diepoxides.

Investigation of temperature-dependent DC breakdown mechanism of EP/TiO2 nanocomposites

In dielectric science, the electrical breakdown strength of a polymeric material significantly decreases with elevated temperatures, which restricts the development of advanced electrical and electronic applications toward miniaturization. In the present study, to clarify the temperature-dependent DC breakdown mechanisms of epoxy resin (EP)/TiO2 nanocomposites, the effects of nanoparticle incorporation and temperature on charge transport and molecular chain dynamics were studied. The results indicate that space charge accumulation and electric field distortion are reduced by nanoparticle incorporation to enhance the deep trap level, while space charge accumulation, electric field distortion, and molecular displacement are all accelerated as temperature increases. To further investigate the influence of carrier traps and molecular chain dynamics on temperature-dependent breakdown, a DC breakdown simulation model that involves bipolar charge transport, molecular chain dynamics, and breakdown criterion equations is established. The calculated breakdown strengths of EP/TiO2 nanocomposites show great accordance with the experimental results, which indicates that temperature-dependent DC breakdown mechanisms are dominated by the synergetic effects of carrier traps and segment chain dynamics. Through the analysis of the breakdown model, a transition of the dominant mechanism (from segment chain to backbone dynamics) near the glass-transition temperature for DC breakdown of EP/TiO2 nanocomposites is discovered.

Surface-Based Post-synthesis Manipulation of Point Defects in Metal Oxides Using Liquid Water.

Initial synthesis of semiconducting oxides leaves behind poorly controlled concentrations of unwanted atomic-scale defects that influence numerous electrical, optical, and reactivity properties. We have discovered through self-diffusion measurements and first-principles computations that poison-free oxide surfaces inject interstitial oxygen atoms into the crystalline solid when simply contacted with liquid water near room temperature. These interstitials diffuse quickly to depths of 20 nm-2 μm and are likely to eliminate prominent classes of unwanted defects or neutralize their action. The mild conditions of operation access a regime for oxide fabrication that relaxes important thermodynamic constraints that hamper defect regulation by conventional methods at higher temperatures. The surface-based approach appears well-suited for use with nanoparticles, porous oxides, and thin films for applications in advanced electronics, renewable energy storage, photocatalysis, and photoelectrochemistry.

Roles of Al2O3@ZrO2 Particles in Modulating Crystalline Morphology and Electrical Properties of P(VDF-HFP) Nanocomposites.

Polymer materials with excellent physicochemical and electrical properties are desirable for energy storage applications in advanced electronics and power systems. Here, Al2O3@ZrO2 nanoparticles (A@Z) with a core-shell structure are synthesized and introduced to a P(VDF-HFP) matrix to fabricate P(VDF-HFP)/A@Z nanocomposite films. Experimental and simulation results confirm that A@Z nanoparticles increase the crystallinity and crystallization temperature owing to the effect of the refined crystal size. The incorporation of A@Z nanoparticles leads to conformational changes of molecular chains of P(VDF-HFP), which influences the dielectric relaxation and trap parameters of the nanocomposites. The calculated total trapped charges increase from 13.63 μC of the neat P(VDF-HFP) to 47.55 μC of P(VDF-HFP)/5 vol%-A@Z nanocomposite, indicating a substantial improvement in trap density. The modulated crystalline characteristic and interfaces between nanoparticles and polymer matrix are effective in inhibiting charge motion and impeding the electric conduction channels, which contributes to an improved electrical property and energy density of the nanocomposites. Specifically, a ~200% and ~31% enhancement in discharged energy density and breakdown strength are achieved in the P(VDF-HFP)/5 vol%-A@Z nanocomposite.

Robust ferroelectric-gating-dependent electronic and magnetic properties in a 1T-VSe2/BiAlO3(0001) multiferroic heterostructure

The modulation of magnetism and related electronic properties is highly desirable for advanced nanoscale electronic and spintronic applications, but volatility in electron spin manipulation is a major challenge that requires urgent attention. Here, we use density functional theory (DFT) calculations to show that the electronic and magnetic properties of a ferromagnetic [half-]metallic 1T-VSe2 monolayer can be effectively modulated via ferroelectric BiAlO3(0001) gating. In particular, the carry type in the 1T-VSe2 overlayer can be switched from being n-type to p-type or n+ -type through the reversal of the ferroelectric polarization. The magnetocrystalline anisotropy of the 1T-VSe2 monolayer can also be changed from easy-plane to easy-axis. In addition, the band offset, magnetic moments, exchange interaction, and Curie temperature (Tc) of the 1T-VSe2 overlayer show significant dependence on the electric polarization direction, with the calculated surface magnetoelectric coupling coefficients (αS) reaching 10−10 G cm [2]/V. This demonstration of robust ferroelectric-gating-dependent magnetism and related electronic properties holds great promise for the innovative design and implementation of next-generation nanoscale non-volatile ultra-low power devices.

Potential soluble substrates for transient electronics applications: A review

The excessive usage and demand of consumer electronics have caused an elevation of electronic waste. Typically, consumer electronics are produced with non-biodegradable, non-biostable, and sometimes fatal materials, resulting in global alarming biological summons. Thence, to mend the drawbacks, an emerging field—named transient electronics—takes effect where the biomaterial, device, substrate, and total systems disappear untraceably after steady-state operation. Conspicuously, transient electronics have induced immense curiosity in researchers to perform interesting investigations due to the feature of disintegration after stable operation. The idea of transient electronics has been implemented in biomedical, military, and nanotechnology fields. Although rapid development is evident in transient technology in a short period, it is believed that the technology will deliver the utmost prospects in advanced electronic applications. Essentially, in transient technology, the vital challenge is to determine the platform materials that offer stability, resistance, biocompatibility, and mainly, the solubility to accommodate the transient devices. In this Review, a detailed overview of different soluble substrates, such as organic, polymer, and solid-state substrates, is described, along with the feasibility of the fabricated devices on the respective substrates to support transient electronics. Second, the dissolving mechanism of the corresponding substrates is analyzed.

Orbital selective switching of ferromagnetism in an oxide quasi two-dimensional electron gas

Multi-orbital physics in quasi-two-dimensional electron gases (q2DEGs) triggers intriguing phenomena not observed in bulk materials, such as unconventional superconductivity and magnetism. Here, we investigate the mechanism of orbital selective switching of the spin-polarization in the oxide q2DEG formed at the (001) interface between the LaAlO3, EuTiO3 and SrTiO3 band insulators. By using density functional theory calculations, transport, magnetic and x-ray spectroscopy measurements, we find that the filling of titanium-bands with 3dxz/3dyz orbital character in the EuTiO3 layer and at the interface with SrTiO3 induces an antiferromagnetic to ferromagnetic switching of the exchange interaction between Eu-4f7 magnetic moments. The results explain the observation of the carrier density-dependent ferromagnetic correlations and anomalous Hall effect in this q2DEG, and demonstrate how combined theoretical and experimental approaches can lead to a deeper understanding of emerging electronic phases and serve as a guide for the materials design of advanced electronic applications.

A Green and Facile Microvia Filling Method via Printing and Sintering of Cu-Ag Core-Shell Nano-Microparticles.

In this work, we developed an eco-friendly and facile microvia filling method by using printing and sintering of Cu-Ag core-shell nano-microparticles (Cu@Ag NMPs). Through a chemical reduction reaction in a modified silver ammonia solution with L-His complexing agent, Cu@Ag NMPs with compact and uniform Ag shells, excellent sphericity and oxidation resistance were synthesized. The as-synthesized Cu@Ag NMPs show superior microvia filling properties to Cu nanoparticles (NPs), Ag NPs, and Cu NMPs. By developing a dense refill method, the porosity of the sintered particles within the microvias was significantly reduced from ~30% to ~10%, and the electrical conductivity is increased about twenty-fold. Combing the Cu@Ag NMPs and the dense refill method, the microvias could obtain resistivities as low as 7.0 and 6.3 μΩ·cm under the sintering temperatures of 220 °C and 260 °C, respectively. The material and method in this study possess great potentials in advanced electronic applications.

Elastic interface in few‐layer graphene/poly(vinylidenefluoride‐trifluoroethylene‐chlorofluoroethylene) nanocomposite with improved polarization

AbstractPolymer film capacitor exhibits extensive applications in advanced electronics because of its flexibility and huge power density. The current research interests of polymer capacitor are addressed on large energy density and high charge–discharge efficiency of composite film. Here we developed the compatible elastic interface composed of hyperbranched poly(methyl acrylate) copolymer in graphene/poly(vinylidenefluoride‐trifluoroethylene‐chlorofluoroethylene) (P(VDF‐TrFE‐CFE)) nanocomposite with high energy capability. This hyperbranched copolymer comprising polyethylene core that was grafted with poly(methyl acrylate) (PMA) segments and pyrene units was synthesized by atom transfer radical polymerization. The few‐layer graphene was exfoliated with assistance of hyperbranched copolymer that was attached on surface of flakes via π‐π non‐covalent interactions between pyrene groups and delocalized π electrons of nanosheets. Graphene/P(VDF‐TrFE‐CFE) nanocomposite film was prepared by solution casting method. The compatibility between graphene and fluoropolymer is greatly improved due to the elastic interphase of PMA segments in hyperbranched copolymer, which enhances the interfacial polarization and decreases the accumulation of charge carriers under high electric field. The energy density of 7.0 J/cm3 with charge–discharge efficiency of 60% at 300 MV/m is achieved for 0.1 wt% nanocomposite. This work reveals an effective architecture of polymer composite with elastic interface to increase the energy capability of polymer dielectric film.

Self-Limiting Opto-Electrochemical Thinning of Transition-Metal Dichalcogenides.

Two-dimensional monolayer and few-layer transition-metal dichalcogenides (TMDs) are promising for advanced electronic and photonic applications due to their extraordinary optoelectronic and mechanical properties. However, it has remained challenging to produce high-quality TMD thin films with controlled thickness and desired micropatterns, which are essential for their practical implementation in functional devices. In this work, a self-limiting opto-electrochemical thinning (sOET) technique is developed for on-demand thinning and patterning of TMD flakes at high efficiency. Benefiting from optically enhanced electrochemical reactions, sOET features a low operational optical power density of down to 70 μW μm-2 to avoid photodamage and thermal damage to the thinned TMD flakes. Through selective optical excitation with different laser wavelengths based on the thickness-dependent band gaps of TMD materials, sOET enables precise control over the final thickness of TMD flakes. With the capability of thickness control and site-specific patterning, our sOET offers an effective route to fabricating high-quality TMD materials for a broad range of applications in nanoelectronics, nanomechanics, and nanophotonics.

Strained α-Sn thin films on highly lattice-mismatched Ge substrates

Strained α-Sn thin films and stanene (two-dimensional counterpart of α-Sn), which have attracted significant attentions due to their electronic properties as topological insulators, were mostly deposited on nearly lattice-matched substrates through molecular beam epitaxy. In this work, contrary to prior efforts, Sn thin films are deposited on highly lattice-mismatched Ge (100) substrates through physical vapor deposition of solid Sn sources. Three different methods, 1) Acetone/Isopropyl Alcohol (IPA), 2) Acetone/IPA/H2O(80°C), and 3) Hydrogen Peroxide (H2O2)/Hydrochloric Acid (HCl), are used to clean commercially available Ge (100) substrates. X-ray diffraction (XRD) characterizations indicate that compressively strained α-Sn thin films are formed on Ge substrates cleaned by Acetone/IPA/H2O(80°C) or H2O2/HCl, but no peak associated with crystalline α-Sn appears for thin films grown on Ge substrates cleaned by Acetone/IPA. Strained α-Sn thin films deposited on Ge substrates cleaned by Acetone/IPA/H2O(80°C) are further investigated using dielectric force microscopy (DFM). Although Ge substrates where α-Sn thin films are deposited are p-type, DFM images indicate that the α-Sn thin films are n-type. The α-Sn/Ge heterostructures that we demonstrate in this work might be promising in applications in advanced electronics and photonics.

Ultra‐Sensitive and Highly Stretchable Strain Sensors for Monitoring of Human Physiology

AbstractThe flexible strain sensors have potential applications in advanced electronics, health monitoring systems, wearable sensors, robotics, and human–machine interfaces. The development of highly sensitive, stretchable, and durable strain sensors is a challenging task for researchers. However, the sensors with a detection range from large strain to minute deflection are imperative for human‐interactive applications. This work has demonstrated a facile method of sensor fabrication, which use reduced graphene oxide (rGO) as sensing material and silicone sealant as a flexible substrate. Few‐layer rGO is synthesized by electrochemical exfoliation of pencil lead. The fabricated sensors have a gauge factor higher than 4000 and durability longer than 1600 cycles at 100% strain. At the same time, developed strain sensors exhibit detection capability over a wide range of strain (0–120%), which is an essential requirement of wearable sensors. To the best of the authors’ knowledge, fewer works have reported strain sensors that have ultra‐high gauge factor (≥4000) in combination with high stretchability (>100%). Utilizing the ultra‐sensitivity and sub‐second response time of the rGO‐sealants, these wearable sensors are used to monitor physical activities, heartbeats, and finger touches.

Nanoscale Ferroelectrics for Advanced Electronics and Microwave Applications [Guest Editorial

The articles in this special section focus on nanoscale ferroelectrics for advanced electronics and microwave applications. THE MOST RECENT DEVELOPments in research into ferroelectric materials, including those that are possibly compatible with CMOS technology, will make it possible to use the substances as widespread insulating-gate dielectrics in microprocessors and largescale integrated circuits. As a matter of fact, growing demand for low-power and ultrafast high-frequency electronics, especially in view of future 6G and In - ternet of Things applications, is driving investigations toward devices operating at increasingly high frequencies by exploiting novel disruptive materials. In this framework, the most promising atomically thin 2D materials are represented by ferroelectrics at nanoscale, whose detailed characterization is be - coming a crucial point.

Energy storage density and charge–discharge properties of PbHf1−xSnxO3 antiferroelectric ceramics

Dielectric capacitors with high energy density, high power density, fast charging-discharge rate and good thermal stability have potential applications in advanced electronics and electric power systems. In this work, the PbHf1-xSnxO3 (PHS) antiferroelectric (AFE) ceramics are prepared via solid-state method. The field-induced AFE to ferroelectric transitions are observed in polarization–electric field (P-E) hysteresis loops. The energy storage capacity increases due to the increase of AFE-ferroelectric switching field despite the field-induced ferroelectric polarization decreases. A high recoverable energy storage density of 10.2 ± 0.4 J/cm3 with high energy efficiency of 78.9% is achieved at 320 kV/cm for x = 0.075 (PHS-0.075) ceramic, which is superior to other systems reported recently. Furthermore, the sample also exhibits excellent stability against testing temperature and frequency. The pulsed charge–discharge process is measured to elucidate the actual operation performance in the PHS ceramic. The PHS-0.075 ceramic possesses a high current density of 1556 A/cm2, a giant power density of 233 MW/cm3 and a fast discharge rate (t0.9 < 360 ns). Delightfully, a remarkable discharge energy density of 7.81 J/cm3 is obtained at 300 kV/cm, which is closer to the actual result for the capacitors operating. This great improvement gives a guideline to further promote the commercialization of AFE materials for energy storage applications.

Examining the Effectiveness of Using Adaptive AI-Enabled e-Learning during the Pandemic of COVID-19.

This study aimed to identify the effect of using adaptive AI-enabled e-learning on developing digital content creative design skills among postgraduate students. The research tools included an achievement test and an observation checklist for rating the practical performance. Research results concluded that, regardless of learning styles, the proposed adaptive e-learning environment had a positive effect on developing both cognitive achievement and practical performance of digital content creative design skills. The results also indicated that there is a significant difference at the 0.01 level between the mean scores of the first experimental group's students using the global learning style-based adaptive e-learning environment and the second experimental group's students using the sequential learning style-based adaptive AI-enabled e-learning environment in the achievement test and observation checklist after measurement of digital content creative design skills in favor of the second experimental group's students. The study provided a number of suggestions and recommendations for making the utmost use of various design layouts of adaptive AI-enabled e-learning environments in developing different cognitive and performance aspects of learning as well as taking full advantage of digital content creative design skills mastery in producing a plethora of advanced electronic educational applications in the foreseeable future.

ABX6 Monolayers: A new Dirac material family containing high Fermi velocities and topological properties

Dirac materials have received attracting attentions due to their intriguing properties and potential applications in advanced electronics. In this work, we reported 44 new two-dimensional Dirac materials, named ABX6 monolayers, by constructing group IVA, VA, and VIA elements with the same structural prototype. Our first principle calculations revealed that they show excellent dynamical stability, mechanical stability, and thermodynamics stability. Those monolayers possess the elastic constant from 23.93 to 245.57 N/m, attributing to broadly used mechanical strength materials. The electronic calculations show that the Dirac cones in all ABX6 monolayers are both located at K points in Brillouin zone and mainly contributed from the pz orbital of group IVA atoms and group VIA atoms. Their Fermi velocities are from 3.44 × 105 to 6.83 × 105 m/s, which is benefiting for the potential applications in high-speed electric devices. Moreover, it is interesting to notice that the ABX6 monolayers with heavy atoms, such as the ISbSn6 monolayer, exhibit a large band gap of ∼ 0.106 eV, due to the spin-orbital coupling effect. The further calculations reveal their nontrivial topological nature with topological edge states, indicating they could be used as potential dissipationless transport devices at room temperature.

Electronic structure transition of cubic CsSnCl3 under pressure: effect of rPBE and PBEsol functionals and GW method

The antiperovskites based on metal halides have emerged as potential materials for advanced photovoltaic and electronic device applications. But the wide bandgap of non-toxic CsSnCl3 reduces its photovoltaic efficiency. Here, we report the change of electronic structure of CsSnCl3 at different pressure by using GGA-rPBE and GGA-PBEsol functionals and the GW method. We have shown that the prediction of electronic structure transition (semiconducting to metallic state) strongly depends on the exchange-correlation and the GW method gives the most reasonable values of the bandgap under pressure. The pressure increases the electronic density of states close to the Fermi level by pushing the valence electrons upward and thus, reduces the bandgap linearly. Afterward, we have also investigated the influence of pressure on absorption coefficient, and mechanical properties meticulously. Although the pressure shifts the absorption peak to lower photon energies, the absorption coefficient is slightly improved.