Device Applications Research Articles

Shortwave-Infrared Silver Chalcogenide Quantum Dots for Optoelectronic Devices.

Silver chalcogenide (Ag2X, X = S, Se, Te) semiconductor quantum dots (QDs) have been extensively studied owing to their short-wave infrared (SWIR, 900-2500 nm) excitation and emission along with lower solubility product constant and environmentally benign nature. However, their unsatisfactory photoluminescence quantum yields (PLQYs) make it difficult to obtain optoelectronic devices with high performances. To tackle this challenge, researchers have made great efforts to develop valid strategies to improve the PLQYs of SWIR Ag2X QDs by suppressing their nonradiative recombination of excitons. In this Perspective, we summarize the significant approaches of heteroatom doping and surface passivation to enhance the PLQYs of SWIR Ag2X QDs, and we conclude their application in high-efficiency optoelectronic devices. Finally, we examine the future trends and promising opportunities of Ag2X QDs with regard to their optical properties and optoelectronics. We believe that this Perspective will serve as a valuable reference for future advancement in the synthesis and application of SWIR Ag2X QDs.

Supercritical CO2-Guided Passivation Strategies for Oxygen Vacancy Modulation in LaMnO3.

The development of 2D magnetic materials and the modulation of intrinsic magnetism are essential for the exploration of new materials in the field of information storage. Despite its strong ferromagnetic properties, LaMnO3 is hindered by a high number of oxygen defects, which result in a relatively short lifetime when employed in electronic memory devices. Here the successful transformation of bulk LaMnO3 into a 2D structure using supercritical carbon dioxide.is reported. This technique enables the successful modulation of the magnetic properties of the material. Interestingly, it is found that the oxygen defect is repaired, which is in sharp contrast to conventional perovskites. These promising results demonstrate the potential of using the magnetic properties of LaMnO3, which is of great importance in the context of expanding its application in electronic devices.

Characterization and Performance Evaluation of Ni-Doped SnO2 Thin Films for Optoelectronic Applications: Structural, Optical, and Electrical Insights

Abstract Undoped and Ni-doped tin oxide thin films were synthesized using the spray pyrolysis technique on ordinary glass substrates. The study aimed to investigate the physico-chemical properties of these thin films using various characterization techniques. X-ray diffraction analysis revealed a polycrystalline behavior with a tetragonal structure and a preferential orientation along the direction for both undoped and Ni-doped SnO2 films. Raman spectroscopy confirm the tetragonal rutile structure and shows a slight enhancement of crystallinity for 4% Ni doped SnO2 thin films. Optical measurements showed a decrease in transmittance with increasing dopant ratio, indicating reduced transparency, and a decrease in band gap with Ni insertion. Electrical measurements, conducted through I-V curve analysis, confirmed Ohm's law compliance and indicated a decrease in resistivity with Ni doping, suggesting improved electrical conductivity. Additionally, the study explored the performance of thin-film solar cells utilizing SnO2 as a transparent conducting layer through numerical simulations using SCAPS-1D software. The effects of Ni doping on the solar cell performance were examined, suggesting potential enhancements or modifications in efficiency and functionality. Overall, the findings provide valuable insights into the structural, optical, and electrical properties of undoped and Ni-doped SnO2 thin films, offering promising avenues for their application in optoelectronic devices.

Advancements and Challenges in Antenna Design and Rectifying Circuits for Radio Frequency Energy Harvesting

The proliferation of smart devices increases the demand for energy-efficient, battery-free technologies essential for sustaining IoT devices in Industry 4.0 and 5G networks, which require zero maintenance and sustainable operation. Integrating radio frequency (RF) energy harvesting with IoT and 5G technologies enables real-time data acquisition, reduces maintenance costs, and enhances productivity, supporting a carbon-free future. This survey reviews the challenges and advancements in RF energy harvesting, focusing on far-field wireless power transfer and powering low-energy devices. It examines miniaturization, circular polarization, fabrication challenges, and efficiency using the metamaterial-inspired antenna, concentrating on improving diode nonlinearity design. This study analyzes key components such as rectifiers, impedance matching networks, and antennas, and evaluates their applications in biomedical and IoT devices. The review concludes with future directions to increase bandwidth, improve power conversion efficiency, and optimize RF energy harvesting system designs.

Tunable electronic and optoelectronic characteristics of two-dimensional g-GeC monolayer: a first-principles study

Two-dimensional (2D) semiconductor materials have emerged as one of the hotspots in recent years due to their potential applications in beyond-Moore technologies. In this work, we systematically investigate the electronic and optoelectronic properties of the g-GeC monolayer combined with strain engineering using first-principles calculations. The results show that g-GeC monolayer possesses a suitable direct bandgap and a strain-tunable electronic structure. On this basis, the designed g-GeC monolayer-based two-probe photodetector exhibits a robust broadband optical response in the visible and near-ultraviolet ranges, along with significant polarization sensitivity and high extinction ratio. In addition, strain engineering can greatly improve the optoelectronic performance of the g-GeC-based photodetector and effectively tune its detection range in the visible and near-ultraviolet regions. These findings not only deepen the comprehension of g-GeC nanosheet but also provide the possibility of its application in nano-optoelectronic devices.

Crystal structure of nickel orthovanadate (Ni3V2O8) at 299 (3) K and 1323 (8) K: an X-ray diffraction study.

Nickel orthovanadate is a promising material with potential applications in energy storage and photocatalytic devices. The crystal structure of Ni3V2O8 at 299 (3) K and 1323 (8) K was studied using X-ray powder diffraction. The sample was a single-phase orthorhombic kagome-staircase-Ni3(VO4)2-type structure (space group Cmca) at both temperatures. The phase purity and morphology was studied using energy-dispersive X-ray spectroscopy and scanning electron microscopy. The refined unit-cell parameters at 299 (3) K are a = 5.93384 (4) Å, b = 11.38318 (7) Å and c = 8.23818 (5) Å, and at 1323 (8) K are a= 6.02077 (7) Å, b = 11.48838 (7) Å and c = 8.32611 (9) Å. The obtained results indicate thermal expansion anisotropy, with a largest expansivity along a. Variations in Ni-O and V-O bonds with temperature are observed. The variation in the Ni-O bond is about one order higher in magnitude than that of the V-O bond, signifying the high rigidity of V-O bonds. The unit-cell size variations with rising effective ionic volume of the divalent A ion in the A3B2O8 family [A = Ni, Mg, Zn, Co, Mn (experimental data) and also A = Cu, Cd (theoretical data), B = V or As] are analyzed. Based on experimental and theoretical data, trends within the family are observed and the unit-cell size for reported solid solution of nickel (87%) and copper (13%) mixture in (Ni1-xCux)3V2O8 are predicted. Predictions are also provided for some hypothetical A3B2O8 ternary compound and solid solutions.

Theoretical aspects of structure, electronic, optical and elastic properties of Ca(1-x)CxSe mixed alloys in binary and ternary phases

The structural, optoelectronic, and elastic properties of Carbon doped Calcium Selenide binary and ternary semiconductor alloys with the general form of Ca(1-x)CxSe, 0 ≤ x ≤ 1 in B1 and B3 phases have been scrutinized adopting augmented plane wave plus local orbital methods within density functional theory applying different approximations like the Local density approximation (LDA), Wu-Cohen-Generalized Gradients Approximation (WC-GGA) and modified Becke-Johnson (mBJ). Structural properties summarize the crystal structure, relevant atomic positions, lattice constant, Bulk modulus B0, minimum energy E0, and minimum volume V0. Elastic constants confirm the structure stability of the B1 and B3 phases. The band gap was modified from a wider for appropriate optoelectronic devices application to narrow that enhanced the range of applicability of these binary and ternary semiconductor compounds for optoelectronic device applications. Whereas optical properties which include the study of zero frequency limit of static dielectric constant ε0(ω) with its real and imaginary parts, static refractive index n(0), optical reflectivity R(ω), optical absorption coefficient α(ω), optical conductivity σ(ω), and loss function L(ω) studied comprehensively to get real electrical and optical properties of these materials and give semiconductor market best alternative candidate which shows its effectiveness in the visible, ultraviolet and infrared region of the electromagnetic spectrum. Obtained results compared together and with the available experimental along with theoretical work on these binary and ternary Carbon-doped Alkaline earth Selenide.

Electrochemical properties of plasticized PVA-based electrolyte inserted with alumina nanoparticles for EDLC application with enhanced dielectric constant

In the current study, the role of alumina nanoparticles was examined in the electrochemical and device performance of PVA-based electrolytes. The NaSCN was used as a cation provider for the host electrolyte, and the glycerol plasticizers were used to enhance conductivity and flexibility. The ratio of salt and plasticizer was fixed, while nanoparticles were varied. The results of impedance AC conductivity confirm that 3 wt% of alumina insertion results in high DC conductivity, which is sufficient for electrochemical device application. Electrode polarization region and plateau area are clearly distinguished in AC spectra. The study of the Dielectric constant reveals that charge storage is maximum at 3 wt% of alumina. The dielectric constant values are about twice the dielectric loss value, which is the topic of immense scientific discussion. The contribution of ion fraction was found to be 0.94, which is excellent compared to the negligible contribution of electrons, which is about 0.05. Electrochemical stability is an additional crucial factor and was found to be 2.47 V. To identify any Redox or non-Redox phenomena occurring in the electrical double-layer capacitor (EDLC) cyclic voltammetry (CV) as the simplest analysis method has been carried out on the sample having the highest DC value. A leaf-like form of the CV plot was noticed at high scan rates, while a rectangular shape was identified at low scan rates. The charge-discharge shape is almost close to the ideal triangular pattern. The discharge part was used to calculate critical EDLC device parameters such as ESR, efficiency, specific capacitance power density, and energy density over 2000 cycles. Low ESR (below 60 Ω) and stable efficiency (almost 100 %) of the device results in high capacitance (≈87 F/g), power density (2978 Wh/kg), and energy density (12.86 W kg−1). The results established that nan-fillers alongside plasticizer is crucial to deliver EDLC devices with improved performances.

"V"-Shaped Changing Electronic Performance of Iodinene-Based Nanoflakes as a Function of Width.

Special structures and prominent performance make 2D iodinene more appealing and valuable at the molecular level. Here, new-type electronic devices have been constructed with iodinene-based nanoflakes in different sizes and are theoretically studied for electronic transport properties. Our findings reveal that iodinene-based nanoflakes possess great electron transport suppression, achieving the same function as SiO2 on single molecule scale. Such transport suppression shows surprisingly nonlinear "V"-shaped trend with the width of the iodinene-based nanoflake. The medium-width iodinene-based nanoflake exhibits the strongest electron transport suppression, while the narrowest and widest ones display the largest electron transmission coefficients due to delocalized transmission eigenstates. Essentially, the weakest electron transport originates from an extremely small DOS and wide HOMO-LUMO gap. Specifically, increasing the width would diminish the extension of electronic states for the dominant transport orbitals, resulting in more butterfly-like electronic states. In non-equilibrium, negative differential resistance effect can be observed in iodinene-based devices, caused by the weakening and staying away from the Fermi level of transmission peaks influenced by the bias. Our findings provide insights into the relationship between the width of iodinene-based nanoflake and electronic transport properties, and lay a foundation in the device design and applications in molecular insulators and controllable-functional devices.

Tunable enhanced chiroptical response of a twisted L-shaped plasmon nanoparticle system

Chiroptical responses in plasmon systems have aroused widespread interest, manifesting potential application in fields including physics, biology, and pharmacy, as well as other disciplines. However, the enhancement and tunability of chiroptical responses by strong plasmon coupling, which have been seldom discussed, remain wanting. In this paper, we propose a stacked and twisted L-shaped nanoparticle system, which exhibits an enhanced chiroptical response and the dynamic modulation of chiroptical response. By adjusting the twist angle and the gap between L-shaped nanoparticles, the anisotropy factor g, which quantifies the relative strength of the chiroptical response, can reach up to −1.5, and the peak position and linewidth of the g spectrum can be modified. Furthermore, in instances where the chiroptical response is weak, we construct a finite-size 1D chain by using the proposed system as the unit cell. By harnessing the global interaction among the unit cell of the 1D chain, the maximum value of g can be effectively improved and adjusted. Such an L-shaped nanoparticle system as a fundamental structure has potential applications in tunable chiroptical devices and also extends methods for device design.

Optical and sign-flipping nonlinear optical properties of NiO/PMMA/PANI nanocomposite films

In this study, we introduce an efficient nanocomposite system to enhance optical properties of Nickel oxide (NiO) integrated with two polymers matrix. NiO nanoparticles is prepared using chemical co-precipitation method and its nanocomposite films (NCFs) were prepared with poly methyl methacrylate (PMMA) and polyaniline (PANI) using drop-casting method on glass substrate and was optimized by changing the concentration of NiO. The prepared NCFs were characterized by X-ray diffraction (XRD), Scanning electron microscopy (SEM), ultraviolet (UV)-visible absorption spectroscopy, photoluminescence (PL) spectroscopy and X-ray photoelectron (XPS) spectroscopy. The open-aperture z-scan method is employed for nonlinear optical investigations, utilizing a nanosecond pulsed laser with a wavelength of 532 nm for excitation. The findings indicate that the NCFs exhibit sign-flipping nonlinear behavior, indicating a transition from saturable absorption to reverse saturable absorption. This suggests that our NCFs exhibit optical limiting properties and potential for applications in photonic devices, such as optical switches and laser protection systems.

Doping dependent magnetic and thermoelectric response of perovskite BaGeO3 for spintronics and energy applications

Using ab-initio simulations, we have investigated the magnetic and thermoelectric response of the pristine and Mn-, Ni-, and In-doped BaGeO3 at Ge-site. The dopants Mn, Ni, and In can be doped at Ge-site due to lower formation energies. The dopants significantly alter the electronics properties of BaGeO3. Interestingly, the In-BaGeO3 exhibits half-metallic nature. Furthermore, our doped system exhibit the magnetic behaviour with 100 % polarization near Fermi level. Additionally, the spin orientation favors the ferromagnetic (FM) states for Mn-BaGeO3. Furthermore, the realization of magnetic anisotropy energy (MAE) may pave the way to use BaGeO3 for applications in magnetic devices. Moreover the zT (0.95) is enhanced for In-BaGeO3. Thus, our studied configuration could potential candidate for thermoelectric insulation as well as thermoelectric cooling applications. We are expecting that our findings could open the ways to utilize the BaGeO3 in the domain of spintronics and magnetic semiconductor devices applications.

Stretchable printed circuit boards using a silicone substrate of variable stiffness and conventional PCB fabrication methods

Abstract Stretchable printed circuit boards (S-PCBs) offer unique advantages over rigid PCBs such as enabling conformability to changing environments and ergonomic designs with increased lifetime under dynamic loads. This study introduces an innovative fabrication method and a cost-effective solution for rapid prototyping S-PCBs using commercially available materials. By utilizing silicone substrates with different levels of stiffness and structured copper sheets for electrical connections, the S-PCBs feature ‘stiff islands’ embedded in a flexible base material. This fabrication method helps alleviate mechanical strain on strain-sensitive components while allowing local deformation of the S-PCB. The proposed fabrication method does therefore enable to integrate surface mount device components into S-PCBs and facilitates complex circuit designs while maintaining stretchability and fatigue resistance. Through material characterization, video strain analysis, as well as quasi-static and cyclic loading tests, this article demonstrates the efficacy of our approach. Based on the experimental results, we provide insights into failure modes and suggest design principles to further enhance the durability of S-PCBs fabricated with our method. We then conclude by presenting a soft wearable S-PCB demonstrator. The S-PCBs fabricated with this method withstood mechanical strains up to 100% and cyclic loads with 30% strain up to 625 cycles. The results are very promising for applications in soft robotics, wearable devices, and soft sensors and actuators. Overall, our study offers a comprehensive toolkit for fast S-PCB prototyping, paving the way for advancements in stretchable electronics with a high degree of complexity and stretchability.

Effect of Temperature on TiO2/P‐Si‐Based Memristor Devices as Optical/Electrical Synapse

Light‐based modulation on resistive switching has opened a new route for development of the devices for advanced applications like integrated switching with memory functionality, neuromorphic computing, and humanoid robotics. This article presents the wafer‐scalable process to fabricate titanium dioxide (TiO2)/porous silicon (P‐Si)‐based heterostructures for memristor applications. The resistive switching performance of the memristor is analyzed using electrical/optical stimulation. The fabricated devices offer enhanced performance metrics during optical stimulation when compared to electrical stimulation. The memristor device offers the paired pulse facilitation (PPF) index of ≈519% (during optical stimulation), which is 3.4 times of the electrical stimulation. Further, the stability and reliability measurements are performed at different temperatures especially (room temperature to 348 K) under 450 nm illumination. The testing results prove that the developed TiO2/P‐Si‐based memristors are suitable for the next‐generation computation systems development.

Electrospinning Recombinant Spider Silk Fibroin-Reinforced PLGA Membranes: A Biocompatible Scaffold for Wound Healing Applications.

Polylactide-polyglycolide (PLGA) is one of the most attractive polymeric biomaterials used to fabricate medical devices for drug delivery and tissue engineering applications. Nevertheless, the utilization of PLGA in load-bearing applications is restricted due to its inadequate mechanical properties. This study examines the potential of recombinant silk fibroin (eADF4), a readily producible biomaterial, as a reinforcing agent for PLGA. The PLGA/eADF4 composite membranes were developed by using the process of electrospinning. The spinnability of the electrospinning solutions and the physicochemical, mechanical, and thermal properties of the composite membranes were characterized. The addition of eADF4 increased the viscosity of the electrospinning solutions and enhanced both the mechanical characteristics and the thermal stability of the composites. This study demonstrates that PLGA membranes reinforced with recombinant spider silk fibroin are noncytotoxic, significantly enhance cell migration and wound closure, and do not trigger an inflammatory response, making them ideal candidates for advanced wound healing applications.

2D Embedded Ultrawide Bandgap Devices for Extreme Environment Applications.

Ultrawide bandgap semiconductors such as AlGaN, AlN, diamond, and β-Ga2O3 have significantly enhanced the functionality of electronic and optoelectronic devices, particularly in harsh environment conditions. However, some of these materials face challenges such as low thermal conductivity, limited P-type conductivity, and scalability issues, which can hinder device performance under extreme conditions like high temperature and irradiation. In this review paper, we explore the integration of various two-dimensional materials (2DMs) to address these challenges. These materials offer excellent properties such as high thermal conductivity, mechanical strength, and electrical properties. Notably, graphene, hexagonal boron nitride, transition metal dichalcogenides, 2D and quasi-2D Ga2O3, TeO2, and others are investigated for their potential in improving ultrawide bandgap semiconductor-based devices. We highlight the significant improvement observed in the device performance after the incorporation of 2D materials. By leveraging the properties of these materials, ultrawide bandgap semiconductor devices demonstrate enhanced functionality and resilience in harsh environmental conditions. This review provides valuable insights into the role of 2D materials in advancing the field of ultrawide bandgap semiconductors and highlights opportunities for further research and development in this area.

Thermodynamic analysis of the inverse electrocaloric effect in ferroelectric thin films

Abstract Inverse electrocaloric (i-EC) effect occurs in ferroelectrics when the applied electric field aligns anti-parallel to polarization. In this study, the dependence of the i-EC effect on temperature and misfit strain is formulated and applied to clamped BaTiO3 thin films using the Landau–Ginzburg–Devonshire formalism. It is found that an interplay exists between the pyroelectric coefficient and the maximum possible inverse electric field. We demonstrate that the temperature change is strongly dependent on the inverse field amplitude and is maximal at lower temperatures away from the ferroelectric-paraelectric transition for a given misfit strain. Such an outcome is opposite to the direct electrocaloric effect, where it is desirable to remain near the transition temperature for the maximum electrocaloric temperature change. The fact that the i-EC effect can be maximum at lower temperatures could allow for the potential tailoring of this effect in strained films at moderate temperatures for device applications.

Charged Impurity Scattering and Electron-Electron Interactions in Large-Area Hydrogen Intercalated Bilayer Graphene.

Intercalation is a promising technique to modify the structural and electronic properties of 2D materials on the wafer scale for future electronic device applications. Yet, few reports to date demonstrate 2D intercalation as a viable technique on this scale. Spurred by recent demonstrations of mm-scale sensors, we use hydrogen intercalated quasi-freestanding bilayer graphene (hQBG) grown on 6H-SiC(0001), to understand the electronic properties of a large-area (16 mm2) device. To do this, we first analyze Shubnikov-de Haas (SdH) oscillations and weak localization, permitting determination of the Fermi level, cyclotron effective mass, and quantum scattering time. Our transport results indicate that at low temperature, scattering in hQBG is dominated by charged impurities and electron-electron interactions. Using low- temperature scanning tunneling microscopy and spectroscopy (STS), we investigate the source of the charged impurities on the nm-scale via observation of Friedel oscillations. Comparison to theory suggests that the Friedel oscillations we observe are caused by hydrogen vacancies underneath the hQBG. Furthermore, STS measurements demonstrate that hydrogen vacancies in the hQBG have an extremely localized effect on the local density of states, such that the Fermi level of the hQBG is only affected directly above the location of the defect. Hence, we find that the calculated Fermi level from SdH oscillations on the millimeter scale agrees with the value measured locally on the nanometer scale with STS measurements.

Theoretical studies of the bipolar properties of ScAlN/AlGaN/GaN heterostructures for enhanced device applications

Abstract Here, we describe a systematic theoretical study of ScAlN/AlGaN/GaN heterostructures for enhanced high-electron-mobility transistors (HEMTs). We have investigated the carrier distributions and energy-band diagrams by solving the coupled Schrödinger and Poisson equations self-consistently. When the heterostructure is in the “off” state, the two-dimensional electron gas (2DEG) becomes increasingly depleted as the ScAlN thickness is increased to the critical thickness, at which point the two-dimensional hole gas (2DHG) appears. This critical thickness depends on the Sc content. Increasing the AlGaN thickness or Al content causes a simultaneous increase in the 2DEG and 2DHG sheet densities. In addition, when the HEMT is in the “on” state, 2DEG sheet density increases as ScAlN thickness increases, so long as the Sc content is less than 0.3; when the Sc content exceeds 0.4, this trend is reversed. For a given Sc content, double channels are produced when the ScAlN thickness exceeds the critical thickness.

Criterion for vanishing valley asymmetric transmission in dual-gated bilayer graphene

Abstract Realizing valley asymmetric transmission(VAT) for incoming valley unpolarized Dirac carriers across an electrostatically modulated confinement potential(ECP) step, which is located at the interface of the unipolar ($n-n'$) junction in dual-gated Bernal-bilayer graphene(BBG), has caught growing attention because it provides a platform to study the valley polarizer. Such a junction, however, seems to preclude from supporting vanishing VAT. Based on the effective two-band Hamiltonian of BBG with wave matching approach, we demonstrate theoretically that VAT through the $n$/$ n'$ interface vanishes in the following conditions: (i) the disappearing electrostatically modulated interlayer potential difference(EPD), or (ii) the invariance condition of the sum or difference of ECPs and EPDs, which physically corresponds to the zero band offset of the conduction or valence band in the band alignment of $n-n'$ junction. Guided by this, it is worth mentioning that the we can derive simple, analytical valley-independent expressions for the reflection and transmission probabilities. We further find the appearance of the nearly vanishing VAT for the four-band model in bilayer graphene with 'Mexican hat'-like band. As a byproduct, we apply these findings to suggest the best design for the valley-dependent selection of momenta based on dual-gated BBG connected to two pristine BBG electrodes in which ECPs of the two outer regions are distinguishable and show that the sign of valley polarization can be switched via varying EPD. We expect our results can provide guidance for future device applications relying on ballistic and valley-selective transport.