Search Results (707)

This work systematically investigates the heteroepitaxial growth of β-Ga₂O₃ thin films under varied substrate and temperature conditions via metalorganic chemical vapor deposition (MOCVD). Comprehensive characterization reveals that both the substrate type and growth temperature significantly influence the crystalline quality, surface morphology, chemical composition, and defect structure. Films grown at higher temperatures generally exhibit superior crystallinity and closer-to-stoichiometry composition, and thus suggest a reduction in oxygen deficiency. Certain substrates are shown to facilitate high-quality epitaxial growth with smooth surfaces and excellent crystallographic alignment. These findings offer key insights into optimizing growth parameters for high-performance β-Ga₂O₃-based devices. Full article

Constructing two-dimensional (2D) novel materials using superatoms as building blocks is currently a highly promising research field. In this study, by employing an oxidation strategy and based on first-principles calculations, we successfully predicted two types of 2D borides, namely B₁₂X₂H₆ (X=O, S), with icosahedral B₁₂ serving as their core structural unit. Ab initio molecular dynamics simulations demonstrated that these two borides exhibit exceptionally high structural stability, retaining their original structural characteristics even under extreme temperature conditions as high as 2200 K. Electronic structure calculations revealed that B₁₂O₂H₆ and B₁₂S₂H₆ are both wide-bandgap indirect semiconductors, with bandgap widths reaching 4.92 eV and 5.25 eV, respectively. Analysis via deformation potential theory showed that the phonon-limited carrier mobilities of B₁₂X₂H₆ can reach up to 1469 cm²V⁻¹s⁻¹ (for B₁₂O₂H₆) and 635 cm²V⁻¹s⁻¹ (for B₁₂S₂H₆). Notably, the surfaces of B₁₂X₂H₆ demonstrate excellent migration performance for alkali metal ions, with migration barriers as low as 0.15 eV (for B₁₂O₂H₆) and 0.033 eV (for B₁₂S₂H₆). This study not only expands the family of 2D materials based on B₁₂ superatoms but also provides a solid theoretical foundation for the potential application of B₁₂X₂H₆ in the field of low-dimensional materials. Full article

In recent years, wide bandgap metal oxide semiconductors have become the base materials of choice for semiconductor gas sensor design. In this work, nanocrystalline ZnO, In₂O₃, and SnO₂ were investigated when detecting NO₂ under UV-photoactivation conditions. The materials were characterized by XRD, low-temperature nitrogen adsorption, and electron microscopy. The article considers the mechanism of sensor signal formation, as well as the mechanism of action of UV-light photoactivation, using an in situ multi-method approach. In situ mass spectrometry and in situ TR-DRIFTS were employed to study the impact of UV-light photoactivation on target gas adsorption equilibrium as well as the electrical and gas-sensing properties of the materials. Full article

The exponential growth of artificial intelligence (AI), electrified transport, and renewable generation is accelerating a structural shift in how societies produce, deliver, and consume electricity. We argue that the next frontier is not incremental efficiency but Energy Intelligence (EI): the embedding of predictive analytics, adaptive control, and material-aware design directly into power-conversion hardware. In this view, power electronics functions as the cognitive layer that links digital intelligence to the physical flow of energy. Wide-bandgap (WBG) semiconductors—gallium nitride (GaN) and silicon carbide (SiC)—provide the material foundation for higher switching frequencies, superior power density, and real-time controllability, enabling compact and efficient converters for data-centers, EV charging, and grid-interactive resources. We formalize an EI reference architecture (predictive, adaptive, material-efficient, data-driven), review the convergence of AI methods with converter design and operation, and outline a GaN/SiC-enabled data-center power path as an illustrative case. Finally, we examine sustainability and sovereignty, highlighting exposure to critical materials (Ga, Si, In, rare earths) and proposing a roadmap that integrates technology, policy, and education. By reframing power electronics as an intelligent, learning infrastructure, this work sets an agenda for systems that are not only efficient but also self-optimizing, explainable, and resilient. Full article

Wide bandgap (WBG) power semiconductors such as silicon carbide (SiC) can significantly improve the performance of multilevel converters. However, there are three challenges for large-scale application: high cost, limited power ratings, and reliability issues. In this paper, we propose a Si and SiC hybrid arms active neutral-point-clamped (ANPC) converter, using smaller current rating SiC devices compared to other Si devices in this topology. By employing the hybrid-frequency modulation scheme, the Si devices switch at fundamental frequency (FF) or low frequency (LF), while the SiC devices switch at high frequency (HF). The equivalent circuit of the proposed converter is derived to analyze the principle of LF current ripple compensation. The closed-loop cooperative current control strategy is proposed to realize unequal current sharing in two arms and complete LF current ripple compensation. The Si arm processes major power, while the SiC arm compensates the LF current ripple generated by the Si arm and processes minor power. The proposed topology and control strategy are validated by simulation and experimental results. Compared with the existing typical topologies, the comprehensive optimization of power quality, efficiency, and cost is realized. Full article

An InGaAs/GaAsSb heterojunction dopingless Tunnel FET with a heterogate dielectric is proposed and investigated in this work, aiming to extend the advantages of dopingless TFETs in low-power applications. By employing the InGaAs/GaAsSb heterojunction with a quasi-broken gap energy band structure in dopingless TFET, the HDL-TFET achieves extremely high band-to-band tunneling efficiency. A dual-electrode structure is adopted to improve carrier distribution, which further enhances tunneling efficiency and increases on-state current (I_ON). To suppress off-state tunneling, optimize ambipolar current, and reduce parasitic capacitance, a heterogate dielectric structure is introduced. Results show that the HDL-TFET exhibits an I_ON up to 8.33 × 10⁻⁵ A/μm and a steep subthreshold swing (SS_avg) of 10.18 mV/dec at a low operating voltage of 0.5 V. It also achieves an off-state current (I_OFF) as low as 3.42 × 10⁻¹⁵ A/μm and I_ON/I_OFF ratio up to 2.44 × 10¹⁰, with no obvious ambipolar current. Compared with previously reported works, the proposed HDL-TFET demonstrates significant advantages. Additionally, the introduction of the heterogate dielectric and dual-electrode structure significantly improves the RF performance of the device, with a peak transconductance (G_m) of 333 μS/μm, and a peak cutoff frequency (f_T) and gain bandwidth product (GBP) up to 64 GHz and 49 GHz, respectively. Full article

Silicon carbide (SiC) has been widely adopted in the semiconductor industry, particularly in power electronics, because of its high temperature stability, high breakdown field, and fast switching speeds. Its wide bandgap makes it an interesting candidate for radiation-hard particle detectors in high-energy physics and medical applications. Furthermore, the high electron and hole drift velocities in 4H-SiC enable devices suitable for ultra-fast particle detection and timing applications. However, currently, the front-end readout electronics used for 4H-SiC detectors constitute a bottleneck in investigations of the charge carrier drift. To address these limitations, a high-frequency readout board with an intrinsic bandwidth of 10 GHz was developed. With this readout, the transient current signals of a 4H-SiC diode with a diameter of 141 μm and a thickness of 50 μm upon UV laser, alpha particle, and high-energy proton beam excitation were recorded. In all three cases, the electron and hole drift can clearly be separated, which enables the extraction of the charge carrier drift velocities as a function of the electric field. These velocities, directly measured for the first time, provide a valuable comparison to Monte Carlo-simulated literature values and constitute an essential input for TCAD simulations. Finally, a complete simulation environment combining TCAD, the Allpix² framework, and SPICE simulations is presented, which is in good agreement with the measured data. Full article

Titanium dioxide (TiO₂) is an important semiconductor material widely used in both fundamental studies and technological applications. Herein, TiO₂ nanorod thin film coatings were fabricated on transparent conductive fluorine-doped tin oxide (FTO) substrates using a hydrothermal synthesis approach, followed by annealing at various temperatures. The effects of annealing temperatures on the Raman and optical absorption spectra were systematically investigated to elucidate the behavior of Raman-active lattice vibrations and optical transitions. As the annealing temperatures increased, both the full width at half maximum of the Raman vibrational modes and the band gap of the TiO₂ nanorod thin films decreased. These trends indicate enhanced crystallinity and phonon lifetimes at higher annealing temperatures. The longer phonon lifetimes contribute to reduced electron–hole recombination, while the narrower band gap extends the optical absorption range into the visible region. This study provides valuable insights into the relationship between annealing temperatures and the structural, vibrational and optical properties of rutile TiO₂ nanorod thin film coatings, highlighting their potential for improved performance in photoelectrocatalytic and optoelectronic applications. Full article

This review examines recent advances in Gallium Nitride (GaN) power semiconductor devices and their growing impact on the development of high-efficiency power conversion systems. It explores innovations in device design, packaging methods, and gate-driving strategies that have improved both performance and reliability. Key metrics such as switching speed, conduction losses, thermal management, and device robustness are analyzed, supported by reliability assessment techniques including Double-Pulse Testing (DPT). The discussion extends to current market dynamics and strategic industry initiatives that have catalyzed widespread GaN adoption. These combined insights highlight GaN’s role as a transformative material offering compact, efficient, and durable power solutions while identifying challenges that remain for broader implementation across diverse industries. Full article

Aluminum nitride (AlN), diamond, and β-phase gallium oxide (β-Ga₂O₃) belong to the family of ultra-wide bandgap (UWBG) semiconductors and exhibit remarkable properties for future power and optoelectronic applications. Compared to conventional wide bandgap (WBG) materials such as silicon carbide (SiC) and gallium nitride (GaN), they demonstrate clear advantages in terms of high-voltage, high-temperature, and high-frequency operation, as well as extremely high breakdown fields. In this work, numerical simulations are performed to evaluate and compare the radiative responses of AlN, diamond, and β-Ga₂O₃ when exposed to neutron irradiation covering the full atmospheric spectrum at sea level, from 1 meV to 10 GeV. The Geant4 simulation framework is used to model neutron interactions with the three materials, focusing on single-particle events that may be triggered. A detailed comparison is conducted, particularly concerning the generation of secondary charged particles and their distributions in energy, linear energy transfer (LET), and range given by SRIM. The contribution of the ¹⁴N(n,p)¹⁴C reaction in AlN is also specifically investigated. In addition, the study examines the consequences of these interactions in terms of electron-hole pair generation and charge deposition, and discusses the implications for the radiation sensitivity of these materials when exposed to atmospheric neutrons. Full article

Photo(electro)-catalysis has increasingly attracted attention from researchers due to its wide applications in green chemical transformation, including organic synthesis and environmental remediation. As a promising candidate, the n-type semiconductor WO₃ possesses a suitable bandgap (~2.6 eV), good visible-light response, high chemical stability, and multi-electron transfer capability, thus endowing it with enormous potential in heterogeneous photocatalysis (PC) and photoelectrocatalysis (PEC) to address environment and energy issues. In this review, the recent research progress of WO₃-based photo(electro)-catalysts is examined and systematically summarized with regard to construction strategies and various application scenarios. To start with, the research background, functionalization methods and possible reaction mechanisms for WO₃ are introduced in depth. Key influencing factors, including light absorption capacity, charge carrier separation, and reusability, are also analyzed. Then, diverse applications of WO₃ for the elimination of organic pollutants (e.g., persistent organic pollutants and polymeric wastes) and green organic synthesis (i.e., oxidation, reduction, and other reactions) are intentionally discussed to underscore their vast potential in photo(electro)-catalytic performance. Finally, future challenges and insightful perspectives are proposed to explore effective WO₃-based materials. This comprehensive review aims to offer profound insights into innovative exploration of high-performance WO₃ semiconductor catalysts and guide new researchers in this field to better understand their vital roles in green organic synthesis and hazardous pollutants removal. Full article

Aluminum nitride (AlN) is a wide-bandgap semiconductor (6.2 eV) with a broad transparency window spanning from the ultraviolet (UV) to the mid-infrared (MIR) wavelength region, making it a promising material for integrated photonics. In this work, AlN thin films using reactive RF sputtering are deposited, followed by annealing at 600 °C in a nitrogen atmosphere to reduce slab waveguide propagation losses. After annealing, the measured loss is 0.84 dB/cm at 978 nm, determined using the prism coupling method. A complete microfabrication process flow is then developed for the realization of optical channel waveguides. A key challenge in the processing of AlN is its susceptibility to oxidation when exposed to water or oxygen plasma, which significantly impacts device performance. The process is validated through the fabrication of microring resonators (MRRs), used to characterize the propagation losses of the AlN channel waveguides. The fabricated MRRs exhibit a quality factor of 12,000, corresponding to a propagation loss of 4.4 dB/cm at 1510–1515 nm. The dominant loss mechanisms are identified, and strategies for further process optimization are proposed. Full article

The electrification of mobility sectors, including automotive, aerospace, and robotics, has accelerated the need for compact and high-efficiency power converters in electric motor drives. Wide-bandgap (WBG) semiconductor–based inverters offer significant advantages over conventional silicon IGBT inverters by enabling higher switching speeds, elevated switching frequencies, and improved power conversion efficiency. However, the adoption of high-frequency switching introduces several challenges, particularly increased motor neutral point voltage stress, originating from inverter common-mode (CM) voltage. The increased neutral point voltage directly elevates motor bearing voltage, the primary driver of motor bearing currents, among which electrostatic discharge machining (EDM) bearing current is the primary cause of bearing degradation in low-power motors. This paper experimentally investigates the root causes of the EDM phenomenon and identifies the key factors influencing its occurrence and severity in WBG-based drive systems. The conventional CM choke designs effectively attenuate motor CM currents and EMI; however, they are ineffective in suppressing EDM bearing currents. In this paper, an alternative CM choke design methodology is proposed to eliminate EDM bearing currents by optimizing the choke inductance to shift the motor CM antiresonance frequency below the inverter switching frequency, thereby ensuring that nearly all source CM voltage is absorbed by the choke. This design approach effectively minimizes the voltage appearing at the motor neutral point and across the bearings, thereby suppressing EDM bearing current spikes without affecting motor DM performance. The choke parameters are mathematically derived for optimal performance and validated through experimental testing on a 2.2 kW three-phase star-connected induction motor powered by a wide-bandgap two-level voltage-source inverter. Full article

In micro gas turbines, electrical power from the high-speed generator is delivered to the grid through a converter that influences overall efficiency and energy quality. This subsystem is often overlooked in efforts to improve turbine performance, which have traditionally focused on combustors and turbomachinery. This study investigates how replacing conventional silicon switching devices in the converter with silicon carbide technology can directly reduce greenhouse gas emissions from micro gas turbines. Although silicon carbide is widely used in electric vehicles and distributed energy systems, its emission reduction impact has not been assessed in micro gas turbines. A MATLAB-based model of a 100 kW Ansaldo Energia micro gas turbine was used to compare the performance of silicon and silicon carbide converters across the 20–100 kW operating range. Silicon carbide reduced total converter losses from 4.316 kW to 3.426 kW at full load, a decrease of 0.889 kW. This improvement lowered carbon dioxide emissions by 5.7 g/kWh and increased net electrical efficiency from 30.03% to 30.29%. Each turbine can therefore avoid about 1.53 tonnes of carbon dioxide annually, or 11.61 tonnes over a 50,000 h service life, without altering turbine design, combustor geometry, or fuel composition. This work establishes the first quantitative link between wide-bandgap semiconductor performance and direct greenhouse gas mitigation in micro gas turbines, demonstrating that upgrading converter technology from silicon to silicon carbide offers a deployable pathway to reduce emissions from micro gas turbines and, by extension, lower the carbon intensity of distributed generation systems. Full article

Ultra-bandgap semiconductor material, β-gallium oxide (β-Ga₂O₃), has great potential for fabricating the next generation of high-temperature, high-voltage power devices due to its superior material properties and cost competitiveness. In addition, β-Ga₂O₃ has the advantages of high-quality, large-size, low-cost, and controllable doping, which can be realized by the melt method. It has a wide bandgap of 4.7–4.9 eV, a large breakdown field strength of 8 MV/cm, and a Baliga figure of merit (BFOM) as high as 3000, which is approximately 10 and 4 times that of SiC and GaN, respectively. These properties enable β-Ga₂O₃ to be strongly competitive in power diodes and metal-oxide-semiconductor field-effect transistor (MOSFET) applications. Most of the current research is focused on electrical characteristics of those devices, including breakdown voltage (V_BR), specific on-resistance (R_ON,SP), power figure of merit (PFOM), etc. Considering the rapid development of β-Ga₂O₃ diode technology, this review mainly introduces the research progress of different structures of β-Ga₂O₃ power diodes, including vertical and lateral structures with various advanced techniques. A detailed analysis of Ga₂O₃-based high-voltage power diodes is presented. This review will help our theoretical understanding of β-Ga₂O₃ power diodes as well as the development trends of β-Ga₂O₃ power application schemes. Full article