Search Results (64)

Considering the cost, efficiency, power density, and other issues of the power electronic system, many papers have mixed the wide-bandgap (WBG) power devices, mainly SiC MOSFET and GaN FET/HEMT, with Si IGBT/MOSFET in the three-level active neutral-point clamped (T-ANPC) topology, forming the hybrid T-ANPC (HT-ANPC) topology. This paper reviews these latest HT-ANPC topologies from the perspective of the material types of switching devices and compares the advantages and disadvantages of various topologies. The potential challenges of HT-ANPC inverters in several mainstream applications are reviewed, and their improvements are compared and discussed in detail. Next, a brief topology selection and design process are provided based on analyzing various typical topologies. In addition, some future research trends on this topic are discussed. The paper will help researchers to select appropriate HT-ANPC topologies in different applications and have a better understanding of the critical issues to be considered during system design. Full article

In order to obtain acceptable efficiencies, hard-switching techniques and the converters that implement them must operate at relatively low frequencies (tens of kilohertz), which translate into converters of large size, weight, and volume, and therefore higher cost. To improve these characteristics, this work introduces a new transformerless MHz-range DC–DC converter that provides symmetrical bipolar outputs. The developed topology uses a single grounded switch, achieves soft switching (ZVS) over a wide load range, and does not require the use of floating or isolated controllers, reducing cost, size, and complexity. The output voltages are self-regulated to maintain the same value, ensuring balanced bipolar operation. A comprehensive analysis, design, sizing, simulation, implementation and testing are provided on a 150 W prototype operating at a switching frequency of 1 MHz, with step-up and step-down capability and implemented with GaN FET. The evaluated configuration shows an efficiency close to 90% and high power density, making it suitable for compact designs in a variety of applications requiring reliable power management and high efficiency such as lighting, electric vehicles, or auxiliary power supplies. Full article

GaN HEMTs based on polarization super junction (PSJ) technology offer significant improvements in efficiency and power density over conventional silicon (Si) devices due to their excellent material characteristics, which enable fast switching edges and lower specific on-resistance. However, due to the presence of an uninterrupted channel between drain and source at zero gate bias, these devices have normally-on characteristics. In this paper, the performance of a 1200 V GaN FET utilizing PSJ technology in cascode configuration is reported. The device working principle, characteristics, and switching behavior are experimentally demonstrated. The results show that cascoded GaN FETs utilizing the PSJ concept are highly promising for power device applications. Full article

The advent of two-dimensional (2D) ferroelectrics offers a new paradigm for device miniaturization and multifunctionality. Recently, 2D α-In₂Se₃ and related III–VI compound ferroelectrics manifest room-temperature ferroelectricity and exhibit reversible spontaneous polarization even at the monolayer limit. Here, we employ first-principles calculations to investigate group-III selenide van der Waals (vdW) heterojunctions built up by 2D α-In₂Se₃ and α-Ga₂Se₃ ferroelectric (FE) semiconductors, including structural stability, electrostatic potential, interfacial charge transfer, and electronic band structures. When the FE polarization directions of α-In₂Se₃ and α-Ga₂Se₃ are parallel, both the α-In₂Se₃/α-Ga₂Se₃ P↑↑ (UU) and α-In₂Se₃/α-Ga₂Se₃ P↓↓ (NN) configurations possess strong built-in electric fields and hence induce electron–hole separation, resulting in carrier depletion at the α-In₂Se₃/α-Ga₂Se₃ heterointerfaces. Conversely, when they are antiparallel, the α-In₂Se₃/α-Ga₂Se₃ P↓↑ (NU) and α-In₂Se₃/α-Ga₂Se₃ P↑↓ (UN) configurations demonstrate the switchable electron and hole accumulation at the 2D ferroelectric interfaces, respectively. The nonvolatile characteristic of ferroelectric polarization presents an innovative approach to achieving tunable n-type and p-type conductive channels for ferroelectric field-effect transistors (FeFETs). In addition, in-plane biaxial strain modulation has successfully modulated the band alignments of the α-In₂Se₃/α-Ga₂Se₃ ferroelectric heterostructures, inducing a type III–II–III transition in UU and NN, and a type I–II–I transition in UN and NU, respectively. Our findings highlight the great potential of 2D group-III selenides and ferroelectric vdW heterostructures to harness nonvolatile spontaneous polarization for next-generation electronics, nonvolatile optoelectronic memories, sensors, and neuromorphic computing. Full article

This paper proposes a design for a platform-based Multi-phase Interleaved Synchronous Buck Converter (MISBC). A custom platform was developed to compare the theoretical performance of a MISBC circuit simulated with Multisim to a prototype that was built at Western Sydney University. The work disclosed in this manuscript describes some steps adopted during the selection of each component and technical considerations taken during the design of the Printed Circuit Board (PCB). The platform designed has a maximum power output of 260 Watts, with a buck reduction of the nominal voltage from 97 Volts to 24 Volts at a maximum switching frequency of 50 kHz. This switching frequency is achieved with an open-loop circuit configuration coupled with synchronized signal generators, used to validate the dead band required between the activation of each set of transistors implemented in a half-bridge configuration. A summary of the results based on the duty cycle required to achieve the buck voltage desired highlights the advantages of each operating mode of the MISBC circuit. Here the theoretical performance is compared against the data acquired during functional evaluations of the prototype, making possible future interpretations of the ideal control algorithm required to maximize the performance output of MISBC circuits. Full article

Nitrogen-based fertilizers are crucial in agriculture for maintaining soil health and increasing crop yields. Soil microorganisms transform nitrogen from fertilizers into ${\mathrm{N}\mathrm{O}}_3^{-}$–N, which is absorbed by crops. However, some nitrogen is converted to nitrous oxide (N₂O), a greenhouse gas with a warming potential about 300-times greater than carbon dioxide (CO₂). Agricultural activities are the main source of N₂O emissions. Monitoring N₂O can enhance soil health and optimize nitrogen fertilizer use, thereby supporting precision agriculture. To achieve this, we developed ionic liquid-gated graphene field-effect transistor (FET) sensors to measure N₂O concentrations in agricultural soil. We first fabricated and tested the electrical characteristics of the sensors. Then, we analyzed their transfer characteristics in our developed N₂O evaluation system using different concentrations of N₂O and air. The sensors demonstrated a negative shift in transfer characteristic curves when exposed to N₂O, with a Dirac point voltage difference of 0.02 V between 1 and 10 ppm N₂O diluted with pure air. These results demonstrate that the ionic liquid-gated graphene FET sensor is a promising device for N₂O detection for agricultural soil applications. Full article

The trapping mechanism at the AlGaN/GaN interface in the p-GaN high electron mobility transistors (HEMTs) and its impact on the turn-on characteristics of direct-coupled FET logic (DCFL) inverters were investigated across various supply voltages (V_DD) and test frequencies (f_m). The frequency-conductance method identified two trap states at the AlGaN/GaN interface (trap activation energy E_c-E_T ranges from 0.345 eV to 0.363 eV and 0.438 eV to 0.47 eV). As V_DD increased from 1.5 V to 5 V, the interface traps captured more electrons, increasing the channel resistance (R_channel) and drift-region resistance (R_drift) of the p-GaN HEMTs and raising the low-level voltage (V_OL) from 0.56 V to 1.01 V. At f_m = 1 kHz, sufficient trapping and de-trapping led to a delay of 220 µs and a V_OL instability of 320 mV. Additionally, as f_m increased from 1 kHz to 200 kHz, a positive shift in the threshold voltage of p-GaN HEMTs occurred due to the dominance of trapping. This shift caused V_OL to rise from 1.02 V to 1.40 V and extended the fall time (t_fall) from 153 ns to 1 µs. This investigation enhances the understanding of DCFL GaN inverters’ behaviors from the perspective of device physics on power switching applications. Full article

This work demonstrates an enhancement mode heterojunction bipolar p-FET (HEB-PFET) structure with a AlGaN/GaN heterojunction bipolar transistor (HBT) integrated on the drain side. Such device design notably contributes to the ultra-high output current density, which is conventionally limited by the low hole mobility and concentration in the p-FETs. The HEB-PFET exhibits an output current density of 241 mA/mm, which is 134 times larger compared to the conventional p-FET (C-PFET) and 2.4 times of the homojunction bipolar p-FET (HOB-PFET). This can be attributed to a better current gain of HBT than homojunction bipolar transistor (BJT). An optimized HEB-PFET of 6 nm p-GaN layer beneath the gate is proposed, where I_ON/I_OFF is >10¹¹, and V_th is −0.44 V. Additionally, thermal stabilities are studied with temperature changes from 300 K to 425 K. Moreover, a semi-empirical compact model is presented to visually explain the working principle of the HEB-PFET. Full article

This paper introduces a novel technology for the monolithic integration of GaN-based vertical and lateral devices. This approach is groundbreaking as it facilitates the drive of high-power GaN vertical switching devices through lateral GaN HEMTs with minimal losses and enhanced stability. A significant challenge in this technology is ensuring electrical isolation between the two types of devices. We propose a new isolation method designed to prevent any degradation of the lateral transistor’s performance. Specifically, high voltage applied to the drain of the vertical GaN power FinFET can adversely affect the lateral GaN HEMT’s performance, leading to a shift in the threshold voltage and potentially compromising device stability and driver performance. To address this issue, we introduce a highly doped n⁺ GaN layer positioned between the epitaxial layers of the two devices. This approach is validated using the TCAD-Sentaurus simulator, demonstrating that the n⁺ GaN layer effectively blocks the vertical electric field and prevents any depletion or enhancement of the 2D electron gas (2DEG) in the lateral GaN HEMT. To our knowledge, this represents the first publication of such an innovative isolation strategy between vertical and lateral GaN devices. Full article

This paper investigates the commutation transients of MOSFET and GaN FET devices in motor drive applications during hard-switching and soft-switching commutations at dead time operation. This study compares the switching behaviors of MOSFETs and GaN FETs, focusing on their performance during dead time in inverter legs for voltage source inverters. Experimental tests at various phase current levels reveal distinct switching characteristics and energy dissipation patterns. A validated simulation model estimates the experimental energy exchanged and dissipated during switching transients. The results demonstrate that GaN FETs exhibit lower overall losses at shorter dead times compared to MOSFETs, despite higher reverse conduction voltage drops. The study provides a quantitative framework for selecting optimal dead times to minimize energy losses, enhancing the efficiency of GaN FET-based inverters in low-voltage motor drive applications. Finally, a dead time optimization strategy is proposed and described. Full article

Power electronics are becoming increasingly more important, as electrical energy constitutes 40% of the total primary energy usage in the USA and is expected to grow rapidly with the emergence of electric vehicles, renewable energy generation, and energy storage. New materials that are better suited for high-power applications are needed as the Si material limit is reached. Beta-phase gallium oxide (β-Ga₂O₃) is a promising ultra-wide-bandgap (UWBG) semiconductor for high-power and RF electronics due to its bandgap of 4.9 eV, large theoretical breakdown electric field of 8 MV cm⁻¹, and Baliga figure of merit of 3300, 3–10 times larger than that of SiC and GaN. Moreover, β-Ga₂O₃ is the only WBG material that can be grown from melt, making large, high-quality, dopable substrates at low costs feasible. Significant efforts in the high-quality epitaxial growth of β-Ga₂O₃ and β-(Al_xGa_1−x)₂O₃ heterostructures has led to high-performance devices for high-power and RF applications. In this report, we provide a comprehensive summary of the progress in β-Ga₂O₃ field-effect transistors (FETs) including a variety of transistor designs, channel materials, ohmic contact formations and improvements, gate dielectrics, and fabrication processes. Additionally, novel structures proposed through simulations and not yet realized in β-Ga₂O₃ are presented. Main issues such as defect characterization methods and relevant material preparation, thermal studies and management, and the lack of p-type doping with investigated alternatives are also discussed. Finally, major strategies and outlooks for commercial use will be outlined. Full article

The semi-bridgeless power factor correction (PFC) rectifier is widely used due to its high power factor, high efficiency, and low electromagnetic interference. However, in this rectifier, the inductor current will flow through the body diode of the metal–oxide–semiconductor field-effect transistor (MOSFET) when the MOSFET does not work, causing a problem in detecting the inductor current. Consequently, the current transformers are generally used as current sensors. This means that using many current sensors will make the cost and the peripheral detection circuit complicated. In this paper, our new method is to use a gallium nitride field-effect transistor (GaNFET) to replace the metal–oxide–semiconductor field-effect transistor (MOSFET) in the main switch selection. The reverse-biased conduction voltage of the third quadrant of the GaNFET is higher than the forward-biased conduction voltage of the diode, which solves the problem in detecting the inductor current, reduces the number of current sensors, and simplifies the corresponding peripheral circuits and components. Eventually, via mathematical deduction and hardware implementation, a semi-bridgeless PFC prototype with a GaNFET was built to verify the effectiveness of the proposed structure. Full article

This paper focuses on the problem of the modeling of FET power transistors made of gallium nitride offered by GaN Systems, Transphorm, and Nexperia. The considered devices have been available on the market since 2014. GaN-FETs are built as a cascade connection of a normally on gallium nitride HEMT and a normally off MOSFET made of silicon. On the manufacturer’s sites, one can find models of these devices for like-SPICE tools in the text form. The main goal of this paper is to evaluate the model’s accuracy by comparing calculation results obtained by the use of the considered models with the authors’ measurement results and datasheet. It has been demonstrated that the GaN Systems model built on controlled sources described by a set of arbitrarily selected mathematical functions more accurately reproduces the basic characteristics of a transistor. On the other hand, the models from Transphorm and Nexperia, which are constructed based on built-in semiconductor device models, more precisely calculate the values of selected functional transistor parameters. Full article

A three-phase GaN-based motor inverter IC with three integrated phase current mirror sensors (sense-FETs or sense-HEMTs, 1200:1 ratio), a temperature sensor, and an amplifier is presented and experimentally operated. The three low-side currents are read out by virtual grounding transimpedance amplifiers. A modified summed DC current readout circuit using only one amplifier is also discussed. During continuous 24 V motor operation with space-vector pulse width modulation (SVPWM), the sensor signal is measured and a bidirectional measurement capability is verified. The measured risetime of the sensor signal is 51 ns, indicating around 7 MHz bandwidth (without intentional optimization for high bandwidth). The IC is operated up to 32 V on DC-biased semi-floating substrate to limit negative static back-gating of the high-side transistors to around −7% of the DC-link voltage. Analysis of the capacitive coupling from the three switch-nodes to the substrate is calculated for SVPWM based on capacitance measurement, resulting in four discrete semi-floating substrate voltage levels, which is experimentally verified. Integrated advanced power converter topologies with sensors improve the power density of power electronics applications, such as for low-voltage motor drive. Full article

This work reports the first nanocrystalline SnON (7.6% nitrogen content) nanosheet n-type Field-Effect Transistor (nFET) with the transistor’s effective mobility (µ_eff) as high as 357 and 325 cm²/V-s at electron density (Q_e) of 5 × 10¹² cm⁻² and an ultra-thin body thickness (T_body) of 7 nm and 5 nm, respectively. At the same T_body and Q_e, these µ_eff values are significantly higher than those of single-crystalline Si, InGaAs, thin-body Si-on-Insulator (SOI), two-dimensional (2D) MoS₂ and WS₂. The new discovery of a slower µ_eff decay rate at high Q_e than that of the SiO₂/bulk-Si universal curve was found, owing to a one order of magnitude lower effective field (E_eff) by more than 10 times higher dielectric constant (κ) in the channel material, which keeps the electron wave-function away from the gate-oxide/semiconductor interface and lowers the gate-oxide surface scattering. In addition, the high µ_eff is also due to the overlapped large radius s-orbitals, low 0.29 m_o effective mass (m_e*) and low polar optical phonon scattering. SnON nFETs with record-breaking µ_eff and quasi-2D thickness enable a potential monolithic three-dimensional (3D) integrated circuit (IC) and embedded memory for 3D biological brain-mimicking structures. Full article