Search Results (40)

The growing demand for electric vehicles, renewable energy systems, and portable electronics has led to the widespread adoption of power conversion systems. Although advanced structures like the superjunction MOSFET have prolonged the viability of silicon in power applications, maintaining its dominance through cost efficiency, Si-based technology is ultimately constrained by its intrinsic limitations in critical electric fields. To address these constraints, research into wide bandgap semiconductors aims to minimize system footprint while maximizing efficiency. This study reviews the semiconductor landscape, demonstrating why Gallium Nitride (GaN) has emerged as the most promising technology for next-generation power applications. With a critical electric field of $3.75\mathrm{MV}/\mathrm{cm}$ ($12.5\times$ higher than Si), GaN facilitates power devices with lower conduction loss and higher frequency capability when compared to their Si counterpart. Furthermore, this paper surveys the GaN ecosystem, ranging from device modeling and packaging to monolithic ICs and switching converter implementations based on discrete transistors. While existing literature primarily focuses on discrete devices, this work addresses the critical gap regarding GaN monolithic integration. It synthesizes key challenges and achievements in the design of GaN integrated circuits, providing a comprehensive review that spans semiconductor technology, monolithic circuit architectures, and system-level applications. Reported data demonstrate monolithic stages reaching $30\mathrm{m}\Omega$ and $25\mathrm{MHz}$, exceeding Si performance limits. Additionally, the study reports on high-density hybrid implementations, such as a space-grade POL converter achieving $123.3\mathrm{kW}/\mathrm{L}$ with $90.9\%$ efficiency. Full article

The tunable bandgap of CIGSe has established bandgap engineering as a pivotal research direction for advancing the efficiency frontiers of solar cells. In particular, the proposal of the V-shaped bandgap gradient has motivated extensive efforts to achieve precise control over elemental composition and spatial distribution within the absorber layer. Against this backdrop, this review systematically classifies active control strategies—such as surface sulfurization, Ga grading, and Ag alloying—according to their doping mechanisms and the resulting bandgap profiles. It further evaluates emerging profiles, including the “hockey-stick” distribution, against the conventional V-shaped benchmark, and explores future pathways for bandgap engineering in next-generation, high-efficiency photovoltaic devices. Further improvements in photovoltaic efficiency can effectively boost power generation and lower solar power costs, providing a practical solution to future energy and environmental challenges. Full article

Due to their long wavelengths and low attenuation characteristics, seismic waves pose serious threats to engineering structures, resulting in an urgent need to develop effective vibration mitigation strategies. Locally resonant phononic crystals provide a novel approach to controlling seismic wave propagation, while auxetic materials have attracted considerable attention for their excellent energy absorption capabilities. To achieve broadband low-frequency seismic isolation, this study proposes a seismic metamaterial composed of embedded dual resonators combined with auxetic materials. The bandgap characteristics of the structure are calculated using the finite element method, and the mechanism of bandgap formation is elucidated through vibrational mode analysis. A parametric study is conducted to investigate the influence of mass block substitution on bandgap tunability, and complex band analysis is employed to evaluate seismic wave attenuation within the bandgap range. Furthermore, a graded composite structure is designed, and its seismic isolation performance is validated through frequency- and time-domain simulations. The results show that the proposed composite structure exhibits significant isolation effects within the 2.7–5 Hz bandgap range. Even under excitation with the Chi-Chi earthquake, whose dominant frequency lies outside the bandgap, the peak ground acceleration is reduced by approximately 42%, and the overall acceleration response is effectively suppressed. These findings provide a promising new design strategy for achieving broadband and low-frequency seismic protection in engineering applications. Full article

We design a one-dimensional magnetoelastic phononic crystal slab composed of the smart magnetostrictive material Terfenol-D and pure tungsten. Band inversion and topological phase transitions are achieved by modifying the geometric parameters of the non-magnetic medium within the unit cell. The emergence of topological interface states within overlapping bandgaps, exhibiting distinct topological properties, along with their robustness against interfacial structural defects, is confirmed. The coupling effects between adjacent topological interface states in a sandwich-like supercell configuration are investigated, and their tunability under external magnetic fields is demonstrated. A Su-Schrieffer-Heeger (SSH) phononic crystal slab system under gradient magnetic fields is proposed. Critically, and in stark contrast to previous static or structurally graded designs, we achieve reconfigurable rainbow trapping of topological interface states solely by reprogramming the gradient magnetic field, leaving the physical structure entirely unchanged. This highly localized, compact, and broadband-tunable topological rainbow trapping system design holds significant promise for applications in elastic energy harvesting, wave filtering, and multi-frequency signal processing. Full article

The increasing penetration of electrified vehicles is accelerating the evolution of on-board and off-board charging systems, which must deliver higher efficiency, power density, safety, and bidirectionality under increasingly demanding constraints. This article presents a system-level review of state-of-the-art charging architectures, with a focus on galvanically isolated power conversion stages, wide-bandgap-based switching devices, battery pack design, and real-world implementation trends. The analysis spans the full energy path—from grid interface to battery terminals—highlighting key aspects such as AC/DC front-end topologies (Boost, Totem-Pole, Vienna, T-Type), high-frequency isolated DC/DC converters (LLC, PSFB, DAB), transformer modeling and optimization, and the functional integration of the Battery Management System (BMS). Attention is also given to electrochemical cell characteristics, pack architecture, and their impact on OBC design constraints, including voltage range, ripple sensitivity, and control bandwidth. Commercial solutions are examined across Tier 1–3 suppliers, illustrating how technical enablers such as SiC/GaN semiconductors, planar magnetics, and high-resolution BMS coordination are shaping production-grade OBCs. A system perspective is maintained throughout, emphasizing co-design approaches across hardware, firmware, and vehicle-level integration. The review concludes with a discussion of emerging trends in multi-functional power stages, V2G-enabled interfaces, predictive control, and platform-level convergence, positioning the on-board charger as a key node in the energy and information architecture of future electric vehicles. Full article

This study presents the development of a high-speed, broadband InGaAs/InP photodiode suitable for advanced sensing and optical detection applications across the critical wavelength range of 850–1550 nm. By employing an InAlAs window layer to replace conventional InP, the device significantly improves sensitivity at 850 nm. Additionally, the substitution of traditional GaAs-based materials with InGaAs enhances responsivity and reduces carrier transit times, enabling precise, high-speed signal detection. The introduction of InGaAsP graded bandgap layers (GBLs) further improves device reliability and reduces absorption losses associated with defects, thus enhancing overall sensing performance. The fabricated photodiode, featuring an active area diameter of 35 µm, achieves high bandwidths of 20 GHz, 15 GHz, and 15.5 GHz at 850 nm, 1310 nm, and 1550 nm, respectively, along with responsivities of 0.5 A/W, 0.72 A/W, and 0.64 A/W. These characteristics make the device well suited for integration into multi-wavelength optical sensing systems, broadband photonic sensors, and high-speed optical communication platforms. Full article

Semiconductor lasers operating at the 730 nm peak wavelength have diverse applications, including biomedical diagnostics, agricultural lighting, and high-precision sensing. However, quantum well (QW) materials, commonly employed at this wavelength, often fail to simultaneously meet the dual requirements of lattice matching and bandgap alignment. In this study, GaAsP/AlGaInP large strain compensation QW with lattice mismatches of −7.533‰ and 1.112‰ was developed. Strain compensation was utilized to address the lattice mismatch while ensuring lasing action at 730 nm. Based on this, the impact of waveguide design, particularly graded and asymmetric waveguides, on the power output was explored. Additionally, the relationship between the doping profile of the device and lasing efficiency was investigated. The completed 100 μm wide semiconductor edge-emitting laser (EEL) achieved 730 nm continuous wave laser with 1 W output power at 2 A current. This study proposes an approach to enhance the lasing power and optoelectronic conversion efficiency of lasers and provide valuable solutions for their practical applications. Full article

Wide Bandgap (WBG) devices like SiC-MOSFETs have become quite popular in recent times due to their superior switching characteristics, high current carrying capability and temperature stability. They are being adopted for many different applications and for a wide range of power levels. For the case of PV applications, manufacturers are considering moving to SiC-based topologies due to higher converter efficiencies and improved power density. However, the present industry largely uses hybrid approaches (IGBT + SiC-diode) to optimize system cost. The aim of this paper is to present a fair comparison of an industry-grade hybrid converter with another similar counterpart where only the Si device has been replaced with the SiC device. The effects of such a direct replacement on the efficiency and losses of the converter are studied under various power ratings. Both converters consist of two stages—a boost converter and a three-phase three-level DC to AC converter. Simulation and experimental results comprehensively indicate a higher efficiency (improvements of up to 8 percent points) for the full-SiC converter, and this is more prominent at low input voltages, where the boost converter is active. However, the gains in efficiency are moderate for high input voltages (1 percent point at nominal voltage), where the boost converter is bypassed, and the losses are almost entirely attributed to the inverter. When set in the backdrop of the Austrian inverter market, the use of SiC devices in PV inverters has the potential for an estimated savings of 37.5 GWh/year in terms of loss reduction. Full article

The green synthesis of metal oxide nanoparticles (NPs) offers an alternative to chemical procedures, which can be harmful to human health due to exposure to hazardous substances and harsh synthesis conditions. The following work synthesized titanium dioxide nanoparticles (TiO₂ NPs) using a green synthesis method. As a precursor, food-grade TiO₂ was used with blueberry extract. This approach makes the process safer, cheaper, and simpler, requiring minimal effort to achieve effective TiO₂ NP synthesis. The TiO₂ NP characterization was performed by solid-state techniques, such as Ultraviolet-visible (UV-Vis) spectroscopy, X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, X-ray photoelectron spectroscopy (XPS), and transmission electron microscopy (TEM). According to the XRD diffractograms, TiO₂ NPs were obtained in the anatase phase with incidence peaks of 25.28 (101). TEM confirmed their pseudo-spherical shape with an average size of 170 nm. The 3.2 eV bandgap of TiO₂ NPs enables UV absorption, making them ideal for efficient photocatalytic degradation under sunlight. On the other hand, the photocatalytic activity of TiO₂ NPs was examined using malachite green (MG) dye as a pollutant model under direct sunlight. After 30 min, a degradation of 94% was achieved. The kinetic analysis identified parabolic diffusion and modified-Freundlich kinetics as primary mechanisms, emphasizing diffusion and adsorption in electron transfer. The main reactive oxygen species (ROS) involved in the photodegradation of MG dye were h⁺ and OH^•. Full article

Beta-phase gallium oxide (β-Ga₂O₃) is a cutting-edge ultrawide bandgap (UWBG) semiconductor, featuring a bandgap energy of around 4.8 eV and a highly critical electric field strength of about 8 MV/cm. These properties make it highly suitable for next-generation power electronics and deep ultraviolet optoelectronics. Key advantages of β-Ga₂O₃ include the availability of large-size single-crystal bulk native substrates produced from melt and the precise control of n-type doping during both bulk growth and thin-film epitaxy. A comprehensive understanding of the fundamental growth processes, control parameters, and underlying mechanisms is essential to enable scalable manufacturing of high-performance epitaxial structures. This review highlights recent advancements in the epitaxial growth of β-Ga₂O₃ through various techniques, including Molecular Beam Epitaxy (MBE), Metal-Organic Chemical Vapor Deposition (MOCVD), Hydride Vapor Phase Epitaxy (HVPE), Mist Chemical Vapor Deposition (Mist CVD), Pulsed Laser Deposition (PLD), and Low-Pressure Chemical Vapor Deposition (LPCVD). This review concentrates on the progress of Ga₂O₃ growth in achieving high growth rates, low defect densities, excellent crystalline quality, and high carrier mobilities through different approaches. It aims to advance the development of device-grade epitaxial Ga₂O₃ thin films and serves as a crucial resource for researchers and engineers focused on UWBG semiconductors and the future of power electronics. Full article

Converting low-grade thermal energy into electrical energy is crucial for the development of modern smart wearable energy technologies. The free-standing films of PEDOT@Bi₂Te₃ prepared by tape-casting hold promise for flexible thermoelectric technology in self-powered sensing applications. Bi₂Te₃ nanosheets fabricated by the solvothermal method are tightly connected with flat-arranged PEODT molecules, forming an S-Bi bonded interface in the composite materials, and the bandgap is reduced to 1.63 eV. Compared with the PEDOT film, the mobility and carrier concentration of the composite are significantly increased at room temperature, and the conductivity reaches 684 S/cm. Meanwhile, the carrier concentration decreased sharply at 360 K indicating the creation of defect energy levels during the interfacial reaction of the composites, which increased the Seebeck coefficient. The power factor was improved by 68.9% compared to PEDOT. In addition, the introduction of Bi₂Te₃ nanosheets generated defects and multidimensional interfaces in the composite film, which resulted in weak phonon scattering in the conducting polymer with interfacial scattering. The thermal conductivity of the film is decreased and the ZT value reaches 0.1. The composite film undergoes 1500 bending cycles with a 14% decrease in conductivity and has good flexibility. This self-supporting flexible thermoelectric composite film has provided a research basis for low-grade thermal energy applications. Full article

This is a comprehensive research endeavor focused on enhancing the efficiency of the proposed solar cell design. The integration of the simulation techniques, judicious material selection, and meticulous performance metrics showcase a methodical approach toward creating a solar cell capable of achieving high efficiency across a wide spectrum of light in the AM 1.5 G1 sun solar cell illumination spectrum. Having said this, many researchers are still working on the efficiency potential—based on external radiative efficiency (ERE), open-circuit voltage loss, and fill factor loss—of high-efficiency solar cells. The solar cell is built on aluminum-doped zinc oxide (ZnO) as a transparent conductive oxide layer; aluminum nitride (AlN) as the window layer (emitter); an SWCNT layer as the absorber layer; gallium phosphide (GaP) as the contact layer; and silicon as the substrate. The proposed solar cell transmission, reflection, and absorption relative to the variations in wavelength band spectrum are studied. The conduction and valence band energy diagrams of the solar cell design structure are simulated against the layer thickness variations for the suggested solar cell structure. Short-circuit current density and maximum power variations are clarified versus the bias voltage. Light current density is simulated versus the bias voltage (J/V characteristics curve) of the suggested solar cell design structure. The carrier generation–recombination rate is also simulated by the COMSOL simulation program versus the layer thickness of the suggested solar cell structure. The solar cell circuit design has a fill factor (FF) value of 74.31% and a power conversion efficiency value of 29.91%. Full article

This research aims to optimize the efficiency of the device structures by introducing the novel double perovskite absorber layer (PAL). The perovskite solar cell (PSC) has higher efficiency with both lead perovskite (PVK), i.e., methylammonium tin iodide (MASnI₃) and Caseium tin germanium iodide (CsSnGeI₃). The current simulation uses Spiro-OMeTAD as the hole transport layer (HTL) and TiO₂ as an electron transport layer (ETL) to sandwich the PVK layers of MASnI₃ and CsSnGeI₃, which have precise bandgaps of 1.3 eV and 1.5 eV. The exclusive results of the precise modeling technique for organic/inorganic PVK-based photovoltaic solar cells under the illumination of AM1.5 for distinctive device architectures are shown in the present work. Influence of defect density (DD) is also considered during simulation that revealed the best PSC parameters with J_SC of 31.41 mA/cm², V_OC of 1.215 V, FF of nearly 82.62% and the highest efficiency of 31.53% at the combined DD of 1.0 × 10¹⁴ cm⁻³. The influence of temperature on device performance, which showed a reduction in PV parameters at elevated temperature, is also evaluated. A steeper temperature gradient with an average efficiency of −0.0265%/K for the optimized PSC is observed. The novel grading technique helps in achieving efficiency of more than 31% for the optimized device. As a result of the detailed examination of the total DD and temperature dependency of the simulated device, structures are also studied simultaneously. Full article

The synthesis of cupric oxide (CuO) films on cost-efficient, optical grade borosilicate-crown glass substrates (BK7) via chemical spray pyrolysis (CSP), either in pure form or with a low concentration of Al doping (below 1%), is presented and discussed. As a non-toxic p-type semiconductor, exhibiting monoclinic crystal structure and widely tuneable band gap (Eg), it is used in various applications. The optical properties, morphology and crystalline phases of CuO films are influenced by substrate temperature during thin film growth (annealing) and also by chemical doping very often introduced to modify grain boundary energy. The importance of our research subject is therefore perfectly justified and is essentially based on the fact that the potential fields of application are wide. Thus, herein we emphasize impact of the annealing stage and Al doping upon the structural, optical and electrical properties of the resulting product. Raman spectroscopy analysis confirms the presence of vibrational bands characteristic of a CuO phase, while X-ray diffraction (XRD) confirms the polycrystalline nature of the pure films. The thickness of the CuO films grown at 350 °C over three annealing intervals is proportional to the annealing time, while the crystallite phase in the films is proportional with the annealing temperature. Furthermore, XRD analysis of the Al:CuO films indicates the formation of a monoclinic-type structure (CuO phase) exhibiting a preferred orientation along the (002) plane, together with a significant grain size reduction from ~88 to ~45 nm as Al content increases. The transmittance spectra (between 400 and 800 nm) reveal a decrease in the transmittance from 48% to 15% with as the Al doping ratio increases. Additionally, the bandgap energy of the films is measured, modelled and discussed, using data from an ultraviolet–visible (UV-Vis) spectrophotometer. The calculated Eg is approximately 3.5 eV, which decreases with respect to the increasing annealing temperature, while the electrical resistivity varies from ~19 to ~4.6 kOhm.cm. Finally, perspectives and applications of CuO films are suggested, since the films are found to have a remarkable improvement in their structure and optical properties when doped with Al. Full article

In order to alleviate the structural vibrations induced by traffic loads, in this paper, a phonon crystal plate with functionally graded materials is designed based on local resonance theory. The vibration damping performance of the phonon crystal plate is studied via finite element numerical simulation and the band gap is verified via vibration transmission response analysis. Finally, the engineering application mode is simulated to make it have practical engineering application value. The results show that the phonon crystal plate has two complete bandgaps within 0~150 Hz, the initial bandgap frequency is 0.00 Hz, the cut-off frequency is 128.32 Hz, and the internal ratio of 0~100 Hz is 94.13%, which can effectively reduce the structural vibration caused by traffic loads. Finally, stress analysis of the phonon crystal plate is carried out. The results show that phonon crystals of functionally graded materials can reduce stress concentration through adjusting the band gap. The phonon crystal plate designed in this paper can effectively suppress the structural vibration caused by traffic loads, provides a new method for the vibration reduction of traffic infrastructure, and can be applied to the vibration reduction of bridges and their auxiliary facilities. Full article