A Linear Model for Characterizing Transient Behaviour in Wide Bandgap Semiconductor-based Switching Circuits

This paper presents the development of a power electronics teaching lab to prepare students for the next generation of power electronics engineering using wide bandgap (WBG) semiconductor devices. The objectives are to expedite the transfer of theoretical knowledge to practical experience on WBG semiconductor devices, and at the same time to provide a hands-on understanding of the development of comprehensive power electronics systems. To incorporate different types of semiconductor devices, especially WBG semiconductor switches, and perform various lab experiments from an investigation of component switching characteristics to construction and operation of power converters, a plug-and-play (P&P) modular power electronics education board is developed. The P&P architecture allows easy construction of different power electronics circuits by simply inserting semiconductor daughter boards to the motherboard. To assist students’ learning experience, the lab curriculum consisting of lab manuals and supporting resources is developed. Multiple workshops have been held with ECE undergraduate and graduate students to evaluate the performance of the lab. Final assessment and student’s feedback are presented as the outcome of the development.

Due to their superior material properties, wide bandgap (WBG) semiconductors enable the application of power electronics at higher temperature operation, higher frequencies, and higher efficiencies compared to silicon (Si). However, the commonly-used aluminum wire bonding as topside interconnection technology prevents WBG semiconductors from reaching their full potential, due to inherent parasitic inductances, large size, heat dissipation, and reliability issues of wire bonding technology. Therefore, this article presents a comprehensive review of topside interconnection technologies of WBG semiconductor power devices and modules. First, the challenges and driving factors for the interconnection of WBG semiconductor dies are discussed. Second, for each widely commercially used WBG semiconductor, i.e., silicon carbide and gallium nitride, technical details and innovative features of state-of-the-art interconnection techniques in packages are reviewed. Then, the majority of existing topside interconnection materials for WBG semiconductors are categorized and compared, followed by a discussion of their advantages, challenges, and failure modes. Based on this elaborate discussion, potential future directions of the interconnection technology development are given. It is concluded that the superior performance of WBG semiconductors can be obtained by combining novel materials with innovative designs for the topside interconnections.

Three phase inverters with switching frequencies above 100 kHz have recently become feasible thanks to the significant progress made in wide band gap (WBG) semiconductor technology. The main drivers behind the intense research and development of these ultrahigh switching frequency pulsewidth modulation (PWM) inverters are the extraordinary gravimetric and volumetric power densities that can be achieved. On the other hand, not as much attention has been devoted to the loads that these inverters supply, quite frequently consisting in ac motors. The impact of sub-MHz PWM and of the associated tens of nanoseconds range switching transients on motor terminal overvoltage, common mode currents, and losses are still to be discussed exhaustively. The authors have thus decided to investigate what happens to induction motors (IM) supplied by inverters having switching frequencies up to 350 kHz. After an introduction on WBG semiconductor devices, the article presents some interesting experimental observations conducted on a 1.1 kW four-pole IM fed by a silicon carbide (SiC) inverter. Further insight is provided by tests on a laminated steel toroid, supplied by a single-phase full bridge SiC inverter. Discussions on the experimental results highlight the previously unreported impact of common mode losses, which become a predominant part of the PWM harmonic losses.

It is worldwide accepted that a real breakthrough in the Power Electronics field mainly comes from the development and use of Wide Band Gap (WBG) semiconductor devices. WBG semiconductors such as SiC, GaN, and diamond show superior material properties, which allow operation at high switching speed, high voltage and high temperature. These unique performances provide a qualitative change in their applications for energy processing. From energy generation to the end-user, the electric energy undergoes a number of conversions, which are currently highly inefficient to the point that it is estimated that only 20% of the whole energy involved in energy generation reaches the end-user. WGB semiconductors increase the conversion efficiency thanks to their outstanding material properties. The recent progress in the development of high voltage WBG power semiconductor devices, especially SiC and GaN, is reviewed. Future trends in device development and industrialization are also addressed.

Devices based on wide bandgap (WBG) semiconductors like silicon carbide (SiC), gallium nitride (GaN), and gallium oxide (Ga2O3) are ideal for high-power electronics in harsh environments. Among the WBG semiconductors, ultrawide bandgap (UWBG) β-phase gallium oxide (Ga2O3), EG ≈ 4.8 eV, is emerging as a replacement for the current commercially available wide bandgap (WBG) power electronics due to its generational improvements in performance and manufacturing cost [1]. Ga2O3 has a high theoretical breakdown electrical field of 8 MV/cm which in turn gives its Baliga’s figure of merit for power devices that is larger than other WBG materials. The availability of high-quality Ga2O3 substrates produced from melt-grown bulk single crystals also facilitates the development of vertical power devices.In the current stage, the vertical Schottky barrier diode (SBD) with Ga2O3 can have an improved current spreading effect when compared to power diode devices from Si, SiC, and GaN. Especially, the Ga2O3 is expected to surpass the trade-off relationship between breakdown voltage (BV) and on resistance (Ron,sp) that other materials have [2]. Nevertheless, the Ga2O3 vertical SBD still cannot achieve the theoretical breakdown electric field. One of the key topics for WBG semiconductors application is a structure for improved electrical management such as field rings, junction termination extension, and field plates to reduce the leakage current in the reverse bias state.Here, we investigate the characteristics of Ga2O3 SBDs with and without mesa structure in extreme environments at high and low temperature. Conventional and mesa Ga2O3 SBDs were fabricated on the halide vapor phase epitaxy (HVPE) grown β-Ga2O3 (001). A Sn-doped substrate with 61016 cm-3 was used for the HVPE growth. In the SBD with mesa structure, the circular mesa with a diameter of 162 μm and a depth of 500 nm was formed around anode electrodes. The Ti/Au metal stack on the back side of the substrate acted as a cathode and the anode electrode deposited Ni/Au/Pt layers. After the fabrication process, current-voltage (I-V) measurements were performed on the SBDs between -5 V and 1 V. From the results, the values of Ron,sp at 0.7 V are 46.4 Ω•cm2 and 46.2 Ω•cm2 in conventional and mesa SBDs, respectively. And additionally, the leakage current at -5 V is reduced by approximately 44.3% in the mesa structure. To obtain the Schottky barrier height (SBH) from I-V and capacitance-voltage (C-V) measurements, the C-V was observed in the range of -5 V to 0.5 V at 100 kHz. The SBH values from I-V and C-V measurements, the mesa SBDs have 1% - 5% larger SBH compared to the conventional structure, and it could be related to lower leakage current. Moreover, the depletion depths of conventional and mesa SBDs were 52.2 nm and 57.8 nm, respectively, from C-V measurements. For considering the electrical characteristics in extreme temperatures, the I-V measurements of both SBDs structure will be measured between 75 K to 525 K. From an initial low temperature measurement series, we determine a Richardson constant of 49 A/cm2 comparable to what has been reported by other groups. Furthermore, we will extend the study by performing deep-level transient spectroscopy (DLTS) to understand the defect information in Ga2O3.

Wide band gap (WBG) semiconductors have progressively gained worldwide attention owing to their wide range of applications in commercially important devices, especially for energy- saving devices and energy harvesting technology. Energy harvesting is one of the vital emerging technologies of the modern era, referring to the collection of energy from the environment. In addition, WBG semiconductors are extensively used in high-performance electronic/optoelectronic devices due to their larger energy band gap, which allows them to absorb/emit a wide range of ultraviolet (UV) light. Recently, mixed wide band gap semiconductors have become more popular and attracted more attention of the researchers due to the possibility of tailoring the materials for specific device applications by adjusting the relative percentages of the constituent compounds, thereby enhancing device performance. A deep analysis of different types of WBG semiconductors and their various applications is crucial for the rapidly evolving modern world.

Power electronic systems have become a key component in the efficient generation, distribution, storage, and use of energy. This increasingly places power electronic systems in harsh environments under elevated stress conditions where, in many cases, their reliable operation is now mission critical. The semiconductor material conventionally used, silicon, possesses limited capability for high temperature applications due to its small bandgap. Power electronic components based on wide bandgap (WBG) semiconductors, such as SiC and GaN, can be operated reliably at higher temperatures. Furthermore, WBG devices have higher breakdown voltages and switching frequencies, rendering them more ideal switches and rectifiers for highefficiency as well as low-volume and low-weight systems. Yet, new packaging concepts are required to make use of the high temperature capability of power electronic systems based on WBG semiconductor devices. In this paper, a summary of the progress in the development and commercialization of wide bandgap power components and power electronic systems is given. The properties of SiC and GaN components are compared to those based on silicon. The shortcomings of conventional power electronic packaging technologies are analyzed, and alternatives introduced and compared. An overview of research is given on Transient Liquid Phase Sintering (TLPS), a promising interconnect technology for the manufacturing of WBG and high temperature power electronic systems. TLPS is a liquid-assisted sintering process during which a low melting temperature constituent melts, surrounds, and diffuses in a high melting temperature constituent. Intermetallic compounds with high melting temperatures are formed by liquid-solid diffusion. Interconnect systems can be processed at low temperatures but are capable of operating at the high melting temperatures of the intermetallic compound. Different process approaches are contrasted and material systems compared. Latest results of research on paste-based low temperature TLPS are presented. The pastes assessed are based on the Cu-Sn and Ni-Sn material systems. It is shown that joints formed by TLPS remain strong up to 600°C and exhibit softening temperatures far higher than conventional interconnect technologies. They show minimum creep and possess very limited voiding. The process does not require an inert or reducing atmosphere or vacuum and is compatible with standard reflow soldering equipment. It shows good wettability to common metallizations such as Cu, Ni, Ag, and ENIG. This attach technology shows the potential to enable reliable operation of wide bandgap power electronic systems under high stress conditions.

Wide bandgap semiconductors enabling highly efficient electrified vehicles

The expansion of the electric vehicle market is driving the request for efficient and reliable power electronic systems for electric energy conversion and processing. The efficiency, size, and cost of a power system is strongly related to the performance of power semiconductor devices, where massive industrial investments and intense research efforts are being devoted to new wide bandgap (WBG) semiconductors, such as silicon carbide (SiC) and gallium nitride (GaN). The electrical and thermal properties of SiC and GaN enable the fabrication of semiconductor power devices with performance well beyond the limits of silicon. However, a massive migration of the power electronics industry towards WBG materials can be obtained only once the corresponding fabrication technology reaches a sufficient maturity and a competitive cost. In this paper, we present a perspective of power electronics based on WBG semiconductors, from fundamental material characteristics of SiC and GaN to their potential impacts on the power semiconductor device market. Some application cases are also presented, with specific benchmarks against a corresponding implementation realized with silicon devices, focusing on both achievable performance and system cost.

Wide bandgap (WBG) and ultrawide bandgap (UWBG) semiconductors in n‐type metal–oxide–semiconductor (n‐MOS) integrated circuits (ICs) are increasingly being explored for their potential applications in the rapidly developing field of electronics. This review comprehensively examines the role of n‐MOS inverters underpinned by WBG and UWBG semiconductors and their application possibilities. It delves into various n‐MOS inverter topologies, including resistive, enhancement or diode‐load, depletion‐load, and pseudo‐complementary MOS inverter topologies. Each topology's operational principles, unique advantages, and potential performance are elucidated in detail. Finally, these topologies are simulated using the Advanced Design System software for a fair comparison between various topologies. The literature and simulation results show that the pseudo‐D topology has the best gain and improved noise margin. The review methodology involves an extensive exploration of WBG/UWBG n‐MOS inverters to advance the current understanding of WBG/UWBG n‐MOS‐based ICs.

HKUST Electronic Theses Characterization and implementation of wide-bandgap semiconductor power devices : dynamic IOFF of GaN HEMT and GaN/SiC cascode device by Yuru Wang thesis 2020 1 online resource (xxiii, 127 pages) : illustrations (some color) Wide-bandgap (WBG) semiconductors, GaN…Read more ›

Wide-bandgap (WBG) semiconductors, typified by silicon carbide (SiC) and gallium nitride (GaN), have revolutionized power electronics due to their exceptional switching speed, thermal conductivity, and voltageblocking capabilities. These advantages enable the development of high-efficiency, miniaturized power converters critical for renewable energy integration, electric vehicles, and aerospace applications. Current short-circuit detection approaches for SiC/GaN wide bandgap (WBG) devices face three critical drawbacks. Single-sensor detection methods are limited by application scenarios and prone to interference. Multi-sensor fusion methods require complex implementation despite balancing speed and robustness. Additionally, the existing detection system lacks compatibility with soft-switching topologies in WBG power converters. This study focuses on short-circuit detection in wide bandgap (WBG) semiconductor devices. A hierarchical classification system for short-circuit detection methods is established, and the transient characteristics of WBG device shortcircuit faults are thoroughly analyzed. The optimization effect of electromagnetic modeling on detection circuits is quantitatively evaluated. A multi-sensor fusion detection strategy balancing speed and robustness is proposed, and application-oriented selection principles for detection methods are clarified. This paper systematically reviews state-of-the-art short-circuit detection methodologies tailored for SiC MOSFETs and GaN HEMTs, categorizing them into single-sensor approaches and multi-sensor fusion strategies (e.g., di/dt + Vgs hybrid method). Core performance metrics—detection speed (ranging from sub-100 ns to over 400 ns), sensitivity to fault signatures, and robustness against electromagnetic interference —are comprehensively analyzed. Critical challenges, including parasitic inductance/capacitance interference, false triggering caused by switching transients, and compatibility with fast-switching dynamics, are discussed in detail. Additionally, the integration of electromagnetic modeling tools (e.g., HFSS, Q3D) for optimizing detection circuit layouts is evaluated, with studies confirming that precise modeling of >100 MHz parasitics is essential for ensuring reliable detection. Finally, current research gaps and future directions are outlined, providing a valuable academic reference for advancing WBG power system protection technologies.

We describe the fabrication and characterization of novel ionizing radiation detectors using wide band gap semiconductors like GaN and synthetic diamond. We have made interdigitated GaN metal-semiconductor-metal (MSM) detector with finger spacing of 8 \(\upmu \)m with Schottky junctions on GaN epitaxial layers. Synthetic diamond grown by microwave plasma-assisted chemical vapor deposition (CVD) is a high-speed detector with applications in high radiation environment. In this paper, we present measurements of current-voltage (I-V) characteristics, charge transport with transient current technique (TCT) and charge collection efficiency measured on GaN and single crystal CVD diamond prototype detectors.

Silicon carbide and nitride based devices have found important commercial applications in both optical and electronic devices. AlGaN deep ultraviolet Light Emitting Diodes (LEDs) are now used for water purification, sterilization, and prolonging food storage. Silicon carbide and gallium nitride based transistors compete with silicon for high power applications and with III-V based transistors for RF applications. The device physics of all these devices is determined by the wurtzite (hexagonal) symmetry leading to strong spontaneous and piezoelectric polarization and by a large polar optical phonon energy, which is the consequence of the strong bonding and small atomic masses of carbon and nitrogen. In AlGaN/GaN and AlGaInN/InGaN devices, the differences in the polarization at the heterointerfaces induce two-dimensional (2D) electron or hole gases at the interfaces (polarization doping) with the electron sheet concentrations up to 10 to 20 times higher than those for more conventional field effect transistors (reaching over 4.5x1013 cm-2 for AlGaN/GaN High Electron Mobility Transistors (HEMTs)). In deep UV LEDs, the polarization induced 2D hole gas is used for improved p-type contacts. A high 2D electron concentration in the III-N HEMT channels enables superior switching characteristics but makes parasitic series resistances and capacitances to be very important. The high current carrying capability and a very high breakdown voltage lead to high power densities and make the issues of heat dissipation to be a priority. The thermal conductivity of SiC (490 W/m K at room temperature) is larger than that for copper (385 W/m K) making it to be an excellent choice as a substrate for power devices. For AlGaN/GaN HEMTs, the research started from using sapphire substrates, but silicon substrates have become a commercial technology. SiC, diamond, or AlN bulk or template substrates could have significant advantages over silicon. The substrates also affect the dislocation and point defect densities in the device channel and strain induced during growth and caused by a strong piezoelectric effect. Such strain is a crucial factor affecting the device reliability (linked to the transient and permanent detects induced under the voltage stress). The large bandgap suppresses the subthreshold leakage making the surface leakage to be one of the dominant leakage mechanisms. Ballistic, overshoot, and electron runaway effects play a dominant role in short channel wide band gap devices now competing for applications in the terahertz (far infrared) range. Figure 1

Challenges and potential payoff for crystalline oxides in wide bandgap semiconductor technology