Practical Electronic Devices Research Articles

Piezostrain control of orbital Rashba effect in Py/CuOx/PMN-PT heterostructures

Electric-field modulated magnetic properties have attracted numerous research studies to elucidate the underlying physics and develop practical electronic devices. In this work, it is demonstrated that the orbital Rashba effect can be modulated by the applied electric field, which is reflected by the variation of charge-to-orbital conversion efficiency ξ under different electric fields in Py/CuOx/PMN-PT heterostructures, where ξ displays a butterfly-like behavior with the electric field, which can be attributed to the piezostrain-mediated magnetoelectric coupling, thus realizing the effective modulation of orbital torque related to the orbital Rashba effect. In addition, our first-principles calculations demonstrate that the orbital moment increases upon increasing strain, which stems from the enhanced p–d hybridization of the interfaced O and Cu atoms. Our results provide a method for modulating the orbital Rashba effect and charge-to-orbital conversion, which shows good potential for practical applications.

Nonvolatile ferroelectric control of electronic properties of Bi2Te3

Abstract Nonvolatile electric-field control of the unique physical characteristics of topological insulators (TIs) is essential for fundamental research and development of practical electronic devices. Electrically tunable transport properties through electrostatic gates have been extensively investigated. However, the relatively weak and volatile tunability limits its practical applications in spintronics. Here, we demonstrate the nonvolatile electric-field control of Bi2Te3 transport properties via constructing ferroelectric Rashba architectures, i.e., 2D Bi2Te3/α-In2Se3 ferroelectric field effect transistors. Through switching the polarization states of the α-In2Se3, the Fermi level, resistance, Fermi wave vector, carrier mobility, carrier density, and magnetoresistance (MR) of the Bi2Te3 film can be effectively modulated. Importantly, a shift of Fermi level toward band gap with surface state occurs as switching to negative polarization state, the contribution of the surface state to the conductivity increases, thereby increasing carrier mobility and electron coherence length significantly, and resulting in enhanced WAL effect. These results provide a nonvolatile electric-field control method to tune the electronic properties of TI and can further extend to the quantum transport properties.

Large‐Scale Ultrastable 2D Inorganic Molecular Crystal BiBr3 and Heterostructures with Superior Photoluminescence Enhancement

AbstractIn contrast to conventional atomic crystals, two‐dimensional inorganic molecular crystals (2DIMCs) possess a unique crystal structure composed of small molecules held together by van der Waals force. Such distinctive structure grants them specific chemical and physical properties highly suitable for electronic and optoelectronic applications. However, the synthesis of 2DIMCs has posed significant challenges due to the inherent issues such as uncontrollable growth orientation stemming from their natural crystalline isotropy and poor stability resulting from the weak intermolecular connections. Addressing these obstacles, the preparation of large‐scale and highly‐stable 2DIMC BiBr3, and its heterostructure are reported here by developing crystallization orientation engineering strategies. This approach has successfully yielded centimeter‐scale 2DIMC BiBr3 with a clean and dense surface, showcasing exceptional long‐term air‐stability exceeding 80 days. Furthermore, the universal growth of large‐scale 2DIMC BiBr3 is demonstrated on diverse substrates, including SiO2, Al2O3, and MoS2 monolayers. Notably, the resultant 2D BiBr3/MoS2 heterostructure exhibits remarkable photoluminescence enhancement. This contribution paves a universal avenue for the mature synthesis of large‐scale 2DIMCs with superior stability, holding great promise for prompting their integration in practical electronic and optoelectronic devices.

Sr4Al2O7: A New Sacrificial Layer with High Water Dissolution Rate for the Synthesis of Freestanding Oxide Membranes.

Freestanding perovskite oxide membranes have drawn great attention recently since they offer exceptional structural tunability and stacking ability, providing new opportunities in fundamental research and potential device applications in silicon-based semiconductor technology. Among different types of sacrificial layers, the (Ca, Sr, Ba)3Al2O6 compounds are most widely used since they can be dissolved in water and prepare high-quality perovskite oxide membranes with clean and sharp surfaces and interfaces; However, the typical transfer process takes a long time (up to hours) in obtaining millimeter-size freestanding membranes, let alone realize wafer-scale samples with high yield. Here, a new member of the SrO-Al2O3 family, Sr4Al2O7 is introduced, and its high dissolution rate, ≈10 times higher than that of Sr3Al2O6 is demonstrated. The high-dissolution-rate of Sr4Al2O7 is most likely related to the more discrete Al-O networks and higher concentration of water-soluble Sr-O species in this compound. This work significantly facilitates the preparation of freestanding membranes and sheds light on the integration of multifunctional perovskite oxides in practical electronic devices.

Machine Learning Driven Channel Thickness Optimization in Dual-Layer Oxide Thin-Film Transistors for Advanced Electrical Performance.

Machine learning (ML) provides temporal advantage and performance improvement in practical electronic device design by adaptive learning. Herein, Bayesian optimization (BO) is successfully applied to the design of optimal dual-layer oxide semiconductor thin film transistors (OS TFTs). This approach effectively manages the complex correlation and interdependency between two oxide semiconductor layers, resulting in the efficient design of experiment (DoE) and reducing the trial-and-error. Considering field effect mobility (𝜇) and threshold voltage (Vth ) simultaneously, the dual-layer structure designed by the BO model allows to produce OS TFTs with remarkable electrical performance while significantly saving an amount of experimental trial (only 15 data sets are required). The optimized dual-layer OS TFTs achieve the enhanced field effect mobility of 36.1cm2 V-1 s-1 and show good stability under bias stress with negligible difference in its threshold voltage compared to conventional IGZO TFTs. Moreover, the BO algorithm is successfully customized to the individual preferences by applying the weight factors assigned to both field effect mobility (𝜇) and threshold voltage (Vth ).

Modified Kramers-Kronig receiver based on memory polynomial compensation for photonics-assisted millimeter-wave communications.

Photonics-assisted millimeter-wave (MMW) wireless communications are advancing rapidly driven by the escalating congestion in the lower-band spectrum and the growing demand for higher data rates. Concurrently, Kramers-Kronig (KK) receivers provide an economical solution ideally suited for cost-sensitive deployment and application. However, the conventional KK receiver is subject to performance degradation due to the nonlinearity and memory effects introduced by practical electronic devices. In this work, the performance degradation of the conventional KK receiver is investigated and quantitatively simulated, showing that the KK receiver exhibits greater sensitivity to nonlinearity and memory effects compared to the conventional coherent receiver. To enhance the performance of KK receivers deployed in MMW communication systems, we propose a modified KK receiver employing memory polynomial compensation, namely MP-KK receiver, capable of effectively compensating memory effects whilst simultaneously addressing nonlinearity. Crucially, the memory polynomial model is employed prior to the KK algorithm to prevent further signal degradation caused by the nonlinear operator in the KK algorithm in the scenario of photonics-assisted MMW wireless communication based on the KK receiver. For verification, we present a 95 GHz W-band MMW wireless transmission demonstration with 20 Gb/s QPSK and 40 Gb/s 16-QAM signals. The experimental results indicate that the MP-KK receiver can achieve more than 3.5 dB improvement in EVM and 71.25% reduction in BER compared to the conventional approaches.

High temperature study of dielectric and electrical conduction behaviour of La2NiO4

Materials showing negative permittivity have attracted considerable attention from researchers on account of their notable applications in electronic and electromagnetic devices. Discovering materials exhibiting negative permittivity is a challenging task. Very few single-phase oxides have been reported as negative permittivity materials. In this work, we have attempted to investigate the dielectric properties of La2NiO4 to explore the possibility of negative permittivity. To achieve the goal, powder, and ceramic of La2NiO4 have been synthesized by the conventional solid-state reaction method. Rietveld refinement of the X-ray diffraction data studies has confirmed the tetragonal structure and space group I4/mmm. The Dielectric properties and AC conductivity have been studied in the frequency range of 20 Hz–2 MHz and over a wide temperature range (30 °C–600 °C). The permittivity of La2NiO4 is found to be negative at all the measured frequencies and temperatures. The Drude model fitted the experimental data very well, suggesting that negative permittivity behavior can be assigned to the plasma oscillation of conducting electrons. The trend of AC conductivity with frequency is similar to the skin effect observed in metals. The variation of DC conductivity with temperature indicated small polaron hopping conduction mechanism. Analysis of reactance (Z′′) suggested inductive electrical character in the tested frequency and temperature range. Room temperature negative permittivity behavior of La2NiO4 makes it a potential candidate for practical electronic and electromagnetic devices that work in the Radio-frequency range. Furthermore, this work will add a new member to the family of Perovskite oxides showing tunable negative permittivity.

Quantum size effect to induce colossal high-temperature energy storage density and efficiency in polymer/inorganic cluster composites.

Polymer dielectrics need to operate at high temperatures to meet the demand of electrostatic energy storage in modern electronic and electrical systems. The polymer nanocomposite approach, an extensively proved strategy for the performance improvement, encounters the bottleneck of reduced energy density and poor discharge efficiency beyond 150°C. Here, we report a polymer/metal oxide cluster composite prepared based on the "site isolation" strategy. Capitalizing on the quantum size effect, the bandgap and surface defect states of the ultra-small inorganic clusters (2.2nm diameter) are modulated to markedly differ from the regular-sized nanoparticles. Experimental results in conjunction with computational simulation demonstrate that, the presence of ultra-small inorganic clusters can introduce more abundant, deeper traps in the composite dielectric with respect to the conventional polymer/nanoparticle blends. Unprecedented high-temperature capacitive performance including colossal energy density (6.8 Jcm-3 ), ultra-high discharge efficiency (95%) and superior stability at different electric field frequencies, are achieved in these polymer/cluster composites up to 200°C. Along with the advantages in material preparation (inexpensive precursors and one-pot synthesis), such polymer/inorganic cluster composite approach is promising for high-temperature dielectric energy storage in practical power apparatus and electronic devices. This article is protected by copyright. All rights reserved.

Improved Thermal Anisotropy of Multi-Layer Tungsten Telluride on Silicon Substrate.

WTe2, a low-symmetry transition metal dichalcogenide, has broad prospects in functional device applications due to its excellent physical properties. When WTe2 flake is integrated into practical device structures, its anisotropic thermal transport could be affected greatly by the substrate, which matters a lot to the energy efficiency and functional performance of the device. To investigate the effect of SiO2/Si substrate, we carried out a comparative Raman thermometry study on a 50 nm-thick supported WTe2 flake (with κzigzag = 62.17 W·m-1·K-1 and κarmchair = 32.93 W·m-1·K-1), and a suspended WTe2 flake of similar thickness (with κzigzag = 4.45 W·m-1·K-1, κarmchair = 4.10 W·m-1·K-1). The results show that the thermal anisotropy ratio of supported WTe2 flake (κzigzag/κarmchair ≈ 1.89) is about 1.7 times that of suspended WTe2 flake (κzigzag/κarmchair ≈ 1.09). Based on the low symmetry nature of the WTe2 structure, it is speculated that the factors contributing to thermal conductivity (mechanical properties and anisotropic low-frequency phonons) may have affected the thermal conductivity of WTe2 flake in an uneven manner when supported on a substrate. Our findings could contribute to the 2D anisotropy physics and thermal transport study of functional devices based on WTe2 and other low-symmetry materials, which helps solve the heat dissipation problem and optimize thermal/thermoelectric performance for practical electronic devices.

Controlled Bipolar Doping of One-Dimensional van der Waals Nb2Pd3Se8.

Tailoring the electrical properties of one-dimensional (1D) van der Waals (vdW) materials is desirable for their applications toward electronic devices by exploiting their unique characteristics. However, 1D vdW materials have not been extensively investigated for modulation of their electrical properties. Here we control doping levels and types of 1D vdW Nb2Pd3Se8 over a wide energy range by immersion in AuCl3 or β-nicotinamide adenine dinucleotide (NADH) solutions, respectively. Through spectroscopic analyses and electrical characterizations, we confirm that the charges were effectively transferred to Nb2Pd3Se8, and the dopant concentration was adjusted to the immersion time. Furthermore, we make the axial p-n junction of 1D Nb2Pd3Se8 by a selective area p-doping using the AuCl3 solution, which exhibits rectifying behavior with an Iforward/Ireverse of 81 and an ideality factor of 1.2. Our findings could pave the way to more practical and functional electronic devices based on 1D vdW materials.

Correlation-driven organic 3D topological insulator with relativistic fermions

Exploring new topological phenomena and functionalities induced by strong electron correlation has been a central issue in modern condensed-matter physics. One example is a topological insulator (TI) state and its functionality driven by the Coulomb repulsion rather than a spin-orbit coupling. Here, we report a ‘correlation-driven’ TI state realized in an organic zero-gap system α-(BETS)2I3. The topological surface state and chiral anomaly are observed in temperature and field dependences of resistance, indicating a three-dimensional TI state at low temperatures. Moreover, we observe a topological phase switching between the TI state and non-equilibrium Dirac semimetal state by a dc current, which is a unique functionality of a correlation-driven TI state. Our findings demonstrate that correlation-driven TIs are promising candidates not only for practical electronic devices but also as a field for discovering new topological phenomena and phases.

Optically active electrochromic polymer films from cyclopenta[2,1-b;3,4-b′]ditiophene prepared in chiral liquid crystal with molecular asymmetry imprinting polymerization

Cyclopenta[2,1-b;3,4-b′]dithiophene (CPDT) based chiral electrochromic (EC) polymer films were synthesized by electrochemical polymerization (EP) in cholesteric liquid crystals (CLCs). We prepared several types of monomers to investigate effects of their planarity and compatibility with host liquid crystals (LCs) on the performance of these polymer films. EP in CLCs had succeeded in imparting chirality transfer to the resultant EC polymer films. Especially, the CPDT-based polymer with methyl group (dMCPDT) showed a large red-shift in the absorption wavelength due to the π-π * transition, and clear circular dichroism (CD). This is because dMCPDT had improved compatibility with the host LCs while maintaining high planarity derived from CPDT backbone. In addition, CPDT with 3,4-ethylenedioxythiophene (EDOT) introduced at both ends resulted polychromaticity by voltage scanning. Furthermore, the CPDT-based polymer has excellent electrochromic properties, fast response time and high cycle stability were observed. Imparting functionality to CPDT-based polymers with high planarity and high charge mobility is preferred for practical electronic device fabrication.

Smart Water Tank Web-based

In this modern era, automatic equipment dominates human life because it can ease the burden of human work. A variety of practical and flexible electronic devices have been created to help people more easily meet their needs. This research designed an automated water tank monitoring system using microcontrollers and utilizing the internet and websites as visualization of monitoring data. This smart water tank consists of pH sensors, turbidity sensors, and TDS sensors. In addition, there is a water level to detect the water level in the reservoir, a solenoid valve as an automatic faucet, and water flow to calculate the discharge of water that fills the reservoir. When tds sensors and turbidity sensors detect water in a bad state it will automatically drain the Tandon. After the water drain is drained, the water level will be detected and then the water pump will automatically turn on. The purpose of this smart water tank is to make it easier for users to monitor the water tank in real time and accurately. The results of the test were carried out that every time the water detects turbidity levels above 25 NTu and Tds above 1000 mg / l then the water will be automatically wasted even though the reservoir is in full condition. The test results also proved the system is able to work by sending water data and displaying it on the web www.tandonair.online.

Electron donor–acceptor (D-A) tuning to achieve soluble covalent organic polymers for optoelectronic devices

Covalent organic polymers (COPs) have emerged as a unique class of luminescent polymers with pre-designed quasi-ordered architectures. However, their layered stacks and limited solubility preclude further processing for large-scale applications in devices, especially optoelectronic equipment. Herein, a universal strategy to adjust the electron donor–acceptor (D-A) moieties of the building blocks in COPs is proposed, achieved by in situ charge exfoliation of COP blocks into few-layer true solutions in (Lewis) acid and base media. The electron D-A moieties of the building blocks endow the COPs with the ability to accept or donate electrons, by altering the electron cloud distribution as well as the relative energy levels of the frontier molecular orbitals. The resultant soluble COPs can easily be processed into a uniform film by solution processing via the spin-coat method. The obtained COP-N achieves efficient and stable perovskite electroluminescence as a novel hole injection material on indium tin oxide, and the operating lifetime for a perovskite quantum dot light-emitting diodes device exceeds that of a poly(ethylene dioxythiophene):polystyrene sulphonate counterpart. This straightforward electronic regulation strategy provides a new avenue for the rational synthesis of processable reticular molecular polymers for practical electronic devices.

Electrochemically exfoliated phosphorene nanosheet thin films for wafer-scale near-infrared phototransistor array

Two-dimensional (2D) black phosphorus (BP), or phosphorene, has recently emerged as a promising 2D semiconductor because of its p-type charge transport behavior and near-infrared photoresponsivity. However, the application of BP in practical electronic and optoelectronic devices is hindered by challenges in producing high-quality BP films over large areas. In this manuscript, we present a facile solution-based process to create wafer-scale BP films for fabrication of p-channel field-effect transistors that are responsive to near infrared light. Few-layer BP nanosheets are first exfoliated from the bulk crystal via electrochemical intercalation of cationic molecules and then vacuum-filtered through an anodic aluminum oxide membrane. The resulting BP film can be transferred onto an SiO2-coated silicon substrate, thereby allowing for realization of field-effect transistors after electrode deposition and thermal annealing. The transistor array exhibits spatial uniformity in electrical performance with an average hole mobility of ~0.002 cm2 V−1 s−1 and on/off ratio of 130. Furthermore, gate-induced modulation of the BP channel allows for enhancement in the photoresponsivity for 1550-nm light illumination up to 24 mA W−1, which benefits the application of the phototransistor array for near infrared imaging.

Multiscale Pseudoatomistic Quantum Transport Modeling for van der Waals Heterostructures

Several electronic and optoelectronic devices have been proposed in recent years based on vertical heterostructures of two-dimensional (2D) materials. The large number of combinations of available 2D materials and the even larger number of possible heterostructures require effective and predictive device-simulation methods, to inform and accelerate experimental research and to support the interpretation of experiments. Here, we propose a computationally effective and physically sound method to model electron transport in 2D van der Waals heterostructures, based on a multiscale approach and quasiatomistic Hamiltonians. The method uses ab initio simulations to extract the parameters of a simplified tight-binding Hamiltonian based on a uniform three-dimensional lattice geometry that enables device simulations using the nonequilibrium Green's function approach in a computationally effective way. We describe the application and limitations of the method and discuss the examples of two use cases of practical electronic devices based on 2D materials, such as a field-effect transistor and a floating-gate memory, composed of molybdenum disulphide, hexagonal boron nitride and graphene.

Development of Biosensors for Ethanol Gas Detection

This work developed a biosensor for the measurement of ethanol gas in the air. The biosensors were synthesized by mixing signal layer materials containing SiO2 and polyimide (PI) substrates using the enzyme Alcohol Dehydrogenase (ADH) and coenzyme Nicotinamide Adenine Dinucleotide (NAD+) as a biosensor. The electrodes were coated on biosensors by DC magnetron sputtering method for test the response performance of the developed biosensors. The ADH/NAD+ was immobilized on the Ag electrode by Glutaric dialaehyde 25 wt. % cross-linking procedure. It was found that, alcohol biosensors can be exhibited sensing ethanol gas at even low concentrations from 300 ppb to very high concentrations up to 1900 ppm, response time 3 s, recovery times 1-2 minutes and good sensitivity. The SiO2 substrate has excellent, which provides significant advantages for wearable electronic device that compact, easy to use and reduce direct contact with alcoholics. The alcohol biosensors can adoption in next generation to other electronic devices, because easy to integrate, such as a module alcohol biosensor with wireless or the fabrication of the RCL circuit. Furthermore, the alcohol biosensors based on SiO2/Ag/ADH, PI/Ag/ADH is artificial intelligence strategy for stable practical wearable electronic devices.

Facile fabrication of highly porous nylon-11 layer for flexible high-performance triboelectric nanogenerator

Here, we report a facile method for the fabrication of flexible triboelectric nanogenerator (TENG) with a porous electropositive triboelectric (TE) layer. The electropositive TE layer composed of a highly porous nylon-11 layer on a conductive fabric is first fabricated by the one-pot method of non-solvent phase separation and then assembled with the electronegative TE layer composed of poly-(vinylidene difluoride) (PVDF) nanofibers to obtain the TENG. The TENG is flexible owing to the incorporation of the porous nylon-11 layer and the PVDF nanofibers. Meanwhile, the TENG exhibits outstanding characteristics, including an output open-voltage of 323 V and a power density of 1.06 W/m2, better than those previously reported values in TENGs with nylon-11 TE layers. To demonstrate its power supply capability, the TENG is further used to power practical electronic devices. Our results provide a facile and low-cost approach for the production of a flexible TENG with high performance.

Tailoring the Electrical Characteristics of MoS2 FETs through Controllable Surface Charge Transfer Doping Using Selective Inkjet Printing.

Surface charge transfer doping (SCTD) has been regarded as an effective approach to tailor the electrical characteristics of atomically thin transition metal dichalcogenides (TMDs) in a nondestructive manner due to their two-dimensional nature. However, the difficulty of achieving rationally controlled SCTD on TMDs via conventional doping methods, such as solution immersion and dopant vaporization, has impeded the realization of practical optoelectronic and electronic devices. Here, we demonstrate controllable SCTD of molybdenum disulfide (MoS2) field-effect transistors using inkjet-printed benzyl viologen (BV) as an n-type dopant. By adjusting the BV concentration and the areal coverage of inkjet-printed BV dopants, controllable SCTD results in BV-doped MoS2 FETs with elaborately tailored electrical performance. Specifically, the suggested solvent system creates well-defined droplets of BV ink having a volume of ∼2 pL, which allows the high spatial selectivity of SCTD onto the MoS2 channels by depositing the BV dopant on demand. Our inkjet-printed SCTD method provides a feasible solution for achieving controllable doping to modulate the electrical and optical performances of TMD-based devices.

N-Type doping of a solution processed p-type semiconductor using isoelectronic surface dopants for homojunction fabrication

The p-n junction is one of the fundamental requirements for a practical semiconductor-based electronic device. Designing a heterojunction comprising of dissimilar p-type and n-type semiconductors calls for careful energy level considerations, both when selecting the semiconductor materials as well as the metal contacts. A homojunction based on a single semiconductor simplifies this task, as energy levels of the p-type and n-type materials are already fairly similar, allowing for easier selection of contacts. Traditionally, homojunctions rely on doping of a bulk semiconductor to achieve p- and n-type transport through controlled addition of aliovalent dopants via energy-intensive processes such as ion implantation or thermal annealing. Exact control of doping in nanocrystalline semiconductors is significantly more challenging, due to self-purification effects. However, owing to their large surface areas, surface moieties can be utilized to both dope the nanostructures as well as tune their energy levels. In this report, we present a facile technique based on an isoelectronic surface dopant in order to achieve p- and n-type materials based on the same semiconductor. We show that thin p-type colloidal Bi2Te3 nanowires can be switched to n-type through surface functionalization, thus increasing the availability of new nanocrystalline solution-processable p-n homojunctions.