Ralf’s GaN & SiC News (March 13, 2025)
Welcome to the latest edition of my newsletter on silicon carbide, gallium nitride, and other wide bandgap semiconductor materials. If you want to get covered, please reach out to me via [email protected]
Content
Breaking News: Navitas unveils production-released bidirectional 650-V GaN switch
A lot of people are working on the monolithic bi-directional GaN switch. With the NV6428 and the NV6427, Navitas Semiconductor has now released the first 650-V devices. This creates a paradigm shift in power with single-stage bi-directional switch converters, enabling the transition from two-stage to single-stage topologies to provide the highest efficiency, power density, and performance while reducing system cost and complexity.
Navitas’ monolithically integrated active substrate clamp automatically connects the substrate to the source terminal with the lowest voltage potential, eliminating a ‘back-gating’ effect, which prevents an undesired increase in R(SS(ON)) when the substrate potential is uncontrolled. This results in a stable R(SS(ON)).
Over 70% of today’s high-voltage power converters use a ‘two-stage’ topology. For example, a typical AC-DC implements an initial power-factor-correction (PFC) stage and a follow-on DC-DC stage, with bulky ‘DC-link’ buffering capacitors. The resulting systems are large, lossy, and expensive. Bi-directional GaNFast consolidates the two stages into a single, high-speed, high-efficiency stage and eliminates the bulky capacitors and input inductors – the ultimate solution in power electronics.
Bi-directional GaNFast advances topologies by directly converting AC input voltage into an AC or DC output voltage. Targeted applications range widely from EV charging (on-board and roadside), solar inverters, energy storage, and motor drives.
Together with the bi-directional switches, Navitas also introduces corresponding driver ICs. IsoFast is a new galvanically-isolated, high-speed driver family optimized to isolate and drive GaN/SiC, including GaN BDS ICs. With 4x higher transient immunity than existing drivers (up to 200 V/ns) and no external negative bias supply needed, they deliver reliable, fast, accurate power control in high-voltage systems.
Gallium Nitride News
Monolithic bidirectional lateral GaN switches reinvigorate power electronics applications
Monolithic bidirectional (BD) voltage/current lateral GaN switches are becoming commercially available, leveraging the “silicon” economies of scale established by the mature lateral power GaN infrastructure. Victor Veliadis and Thomas M. Jahns review key features of major alternative BD device architectures. In particular, monolithic BD switches with a dual-gate structure are advantageous since they have a common drain region that reduces cell-pitch and on-state resistance R(on) and only increase switch area by about 1.2X compared to similarly rated commercial GaN unidirectional voltage blocking devices.
Many types of power electronics applications benefit very directly and, in some cases, dramatically from the commercial availability of monolithic BD switches. Four promising candidate applications are briefly discussed, including matrix converters, current-source inverters, T-type multi-level voltage-source inverters, and solid-state circuit breakers. The article closes with an acknowledgment of the practical obstacles to the commercial production of monolithic BD switches and reasons for optimism that these obstacles will be overcome.
V. Veliadis and T. M. Jahns, "Monolithic Bidirectional Lateral GaN Switches Reinvigorate Power Electronics Applications," in IEEE Power Electronics Magazine, vol. 12, no. 1, pp. 22-28, March 2025, doi: 10.1109/MPEL.2025.3528696.
GaN bidirectional switches: The revolution is here
GaN bidirectional switches unlock the design of single-stage AC-DC topologies with smaller part count and higher efficiency than incumbent dual-stage topologies. Because of GaN lateral architecture, bidirectional switches can be monolithically integrated on the same chip, conducting current and blocking voltage in both directions. Being monolithically integrated, GaN bidirectional switches share a single drift region and have no back-to-back drain contacts, resulting in a significant figure of merit advantage. They fit in one package for significant cost and system size reduction.
In this article, Davide Bisi reviews the main single-stage topologies and bidirectional device architectures. He discusses prototype results and future products. At the end, he provides guidelines on how to use GaN bidirectional switches easily and safely and discusses qualification and reliability procedures.
Davide Bisi, "GaN Bidirectional Switches: The Revolution is Here," in IEEE Power Electronics Magazine, vol. 12, no. 1, pp. 29-36, March 2025, doi: 10.1109/MPEL.2024.3522985.
EPC publishes Reliability Report Phase 17
The rapid adoption of GaN devices in many diverse applications calls for the continued accumulation of reliability statistics and research into the fundamental physics of failure in GaN devices, including ICs. In this Phase 17 Reliability Report, EPC - Efficient Power Conversion presents ongoing efforts using test-to-fail methodology to develop more comprehensive and advanced lifetime models, which aim to accurately project the reliability of GaN devices under more complex mission-specific operating conditions.
The latest Phase 17 reliability report further expands the first-principles lifetime models to address more complex operating conditions, enabling more accurate lifetime projections for mission-specific applications. Additionally, the latest version focuses on presenting the complex physics-based models in various application-driven, user-friendly formats, allowing readers to comprehend the concepts quickly and apply them to practical use conditions with ease.
Cambridge GaN Devices to demonstrate Combo ICeGaN by the end of this year
To address EV powertrain applications over 100kW with its ICeGaN technology, Cambridge GaN Devices Ltd (CGD) presents Combo ICeGaN. It combines smart ICeGaN HEMT ICs and silicon IGBTs in the same module or IPM, maximizing efficiency and offering a cost-effective alternative to expensive SiC solutions. CGD expects to have working demos of Combo ICeGaN at the end of this year.
In operation, the ICeGaN switch is very efficient, with low conduction and low switching losses at relatively low currents (light load), while the IGBT is dominant at relatively high currents (towards full load or during surge conditions). Combo ICeGaN also benefits from the high saturation currents and the avalanche clamping capability of IGBTs, and the very efficient switching of ICeGaN. At higher temperatures, the bipolar component of the IGBT will start to conduct at lower on-state voltages, supplementing the loss of current in the ICeGaN. Conversely, at lower temperatures, ICeGaN will take more current.
Webinar: Designing with GaN: Overcoming challenges in power management
GaN solutions offer higher voltage conversion, smaller form factors, and improved power efficiency. However, designing with GaN HEMTs presents unique challenges. Engineers must carefully select components, design the drive stages, and ensure optimal placement for reliable operation. This webinar, presented by everything PE and held by 亚德诺半导体 , will help you successfully integrate GaN power products into your next design.
Miscellaneous News
ECPE SiC & GaN User Forum in Paris (France)
This year’s ECPE European Center for Power Electronics SiC & GaN User Forum will take place from 3 to 4 April 2025 in the vibrant city of Paris, France. This forum has been a cornerstone for over 18 years, guiding professionals in integrating SiC and GaN semiconductor devices into power electronic systems.
This year's program will delve into:
In the Keynote session, Gerald Deboy ( 英飞凌 ) and Balu Balakrishnan ( Power Integrations ) will talk about GaN integration.
Call for Papers: Special Issue of IEEE Transactions on Electron Devices on "Wide Band Gap Semiconductors for Automotive Applications"
Focusing on the automotive sector, WBG semiconductors offer tremendous potential for enhancing vehicle performance and efficiency in various applications, including the electric drivetrain, battery management systems, and onboard chargers. This, in turn, leads to increased driving range and a significant reduction in charging times in EVs.
In essence, the utilization of wide bandgap semiconductors in automotive systems offers an avenue for achieving significantly improved performance and efficiency, reduced emissions, and greater reliability while improving sustainability in transportation.
Topics of interest for this special issue include, but are not limited to:
Submission deadline: October 31, 2025
Publication date: June 2026
Submission site: https://ieee.atyponrex.com/journal/ted
Application and prospect of in-situ TEM in wide bandgap semiconductor materials and devices
Diamond, Ga?O?, GaN, and SiC are typical WBG semiconductor materials. Reliability studies for these four materials and devices are crucial for WBS applications. Traditional means of reliability studies include, but are not limited to, x-ray diffraction, atomic force microscopy, Raman spectroscopy, and electron microscopy. However, most of these methods are ex-situ studies after material or device failure and thus have some limitations.
In-situ transmission electron microscope (TEM) is a favorable technology to observe the degradation and failure process of materials and devices in real time, which may provide effective guidance in material growth, device structure design, device process optimization, and reliability improvement. In recent years, in-situ TEM technology has been gradually used by researchers to study WBG materials and devices.
In this review, researchers from Xidian University present a comprehensive and systematic review of in-situ TEM works on diamond, Ga?O?, GaN, and SiC materials and devices, with a particular focus on the progress of the technology in the reliability study of such materials and devices. While summarizing the advantages of in-situ TEM in the investigation of WBS materials and devices, the review also looks forward to the future of in-situ TEM in promoting the study of WBG materials and devices.
Chao Chen, Tao Zhang, Yimin Lei, Jiatong Fan, Le Zhang, Ge Wang, Luyao Gao, Peixian Li, Qing Zhu, Xiaohua Ma, Yue Hao; Application and prospect of in situ TEM in wide bandgap semiconductor materials and devices. Appl. Phys. Rev. 1 March 2025; 12 (1): 011326. https://doi.org/10.1063/5.0225128
Ultra-Wide Bandgap News
Seed-driven stepwise crystallization for growing rutile GeO? films via MOCVD
Germanium dioxide (r-GeO?) is an emerging UWBG semiconductor with significant potential for power electronics, thanks to its ambipolar doping capability. However, phase segregation during MOCVD on substrates like r-TiO? has posed a significant barrier to achieving high-quality films. Conventional optimization of growth parameters has been found so far not very insufficient in film coverage and film quality.
To address this, researchers from the University of Utah employed a seed-driven stepwise crystallization (SDSC) growth approach in this study, featuring multiple sequential deposition steps on a pretemplated substrate enriched with r-GeO? seeds. The process began with an initial 180 min deposition to establish r-GeO? nucleation seeds, followed by a sequence of shorter deposition steps (90, 60, 60, 60, 60, and 60 min). This stepwise growth strategy progressively increased the crystalline coverage to 57.4, 77.49, 79.73, 93.27, 99.17, and ultimately 100%. Concurrently, the crystalline quality improved substantially, evidenced by a ～30% reduction in the Full Width at Half Maximum (FWHM) of X-ray diffraction rocking curves.
These findings demonstrate the potential of the SDSC approach for overcoming phase segregation and achieving high-quality, large-area r-GeO? films.
Imteaz Rahaman , 李博同 , Bobby Duersch , Hunter Ellis , Kai Fu , ACS Appl. Electron. Mater., American Chemical Society, doi: 10.1021/acsaelm.4c02361
Suppression of screw dislocation-induced hillocks in MOCVD-grown α-Ga?O? on m-plane sapphire by introducing a high-temperature buffer
In this study, a research team from 山东大学（威海） , the 中国科学院 , and the 电子科技大学 successfully grew pure-phase α-Ga?O? films on m-plane sapphire substrates by using MOCVD and systematically investigated the impact of various growth parameters on the resulting film characteristics.
The crystallization quality of the films improved by adjusting the VI/III ratio, ultimately yielding a symmetric rocking curve full width at half-maximum (fwhm) of 0.39° for the (300) diffraction. The surface morphology of α-Ga?O? films exhibited a layer-by-layer growth mode characterized by a remarkably flat surface (RSM = 0.365 nm) in the early growth stage. Nevertheless, as the film thickness increased, the appearance of hillock defects composed of β-Ga?O? detrimentally impacted the surface quality. To mitigate this issue, a high-temperature buffer layer was introduced to inhibit the formation of hillocks.
This approach resulted in α-Ga?O? films on m-plane sapphire with substantial thickness and exceptional surface quality, establishing a robust foundation for the future fabrication of heterojunction devices.
Zhucheng Li, et al., Suppression of screw dislocation-induced hillocks in MOCVD-grown α-Ga?O? on m-plane sapphire by introducing a high-temperature buffer, Crystal Growth & Design 2025 25 (5), 1406-1414, DOI: 10.1021/acs.cgd.4c01472
A review of vertical Ga?O? diodes: From fabrication to performance optimization and future outlooks
Recently, Ga?O? has emerged as a promising alternative for SiC and GaN, offering an ultra WBG of 4.8?eV and a breakdown electric field of 8?MV/cm while benefiting from relatively simple and cost-effective growth methods. Despite these advantages, Ga?O? has limitations, including low electron mobility and poor thermal management, which restrict its use primarily to high-voltage, low-frequency applications such as diodes.
This article from researchers at KAUST (King Abdullah University of Science and Technology) analyzes recent developments in Ga?O? diodes, providing an overview of their properties, fabrication techniques, and application-specific performance. The challenges Ga?O? diodes currently face are examined, particularly in thermal management and electron mobility, and ongoing research efforts aimed at overcoming these issues to enable broader use of Ga?O? diodes in power electronics are discussed.
José Manuel Taboada Vásquez , Xiaohang Li , (2025), A Review of Vertical Ga?O? Diodes: From Fabrication to Performance Optimization and Future Outlooks. Phys. Status Solidi B 2400635. https://doi.org/10.1002/pssb.202400635
Job Exchange
Post-doc at CEA: Comparison of Diamond and vertical GaN technologies to SiC and Si for power applications
Power devices based on wide bandgap semiconductors are increasingly being studied and adopted in commercial products, driven by the electrification of our societies. Among these wide bandgap devices, SiC-based technologies are the most mature at the industrial production stage. Other materials are being studied to achieve higher performance, in particular, diamond, whose intrinsic physical properties offer great potential, as well as GaN components in a vertical architecture. However, the real benefits of these materials compared with existing Si or SiC solutions have not been clearly demonstrated and might strongly depend on the applications considered.
This project at 原子力? 代替エネルギー庁 (CEA) aims to identify one or more applications where vertical GaN and diamond technologies are likely to bring significant benefits, considering the current and/or projected market for these applications. Then, using TCAD and SPICE simulations as well as experimental test device characterizations, we will compare the estimated performance of industrially viable diamond and GaN components designed for these applications with that of SiC and Si.
Silicon Carbide News
ST’s TPak for Tesla - Two BONDs are better than one
意法半导体 is the lead supplier for Tesla 's SiC MOSFET inverters. It utilizes a custom package called the "Tpak" that is suited for the construction techniques used in Tesla's Model 3/Y traction inverter.
In examining the construction of the gate bonds during this teardown, Kevin Matocha found that the gate bonds are "double-stitched" to the AMB dogbone. This contrasts with the construction of original releases of this part. The observation of a double-stitch gate wirebond differs from the 2018 teardown from Yole SystemPlus : the original release of the Tpak had a single-stitch gate wirebond.
Why two bonds?
One possible SiC MOSFET failure mode is loss of gate control due to losing the gate wirebond connection. For the relatively large Tpak, the gate wirebond could incur failure due to delamination of the mold-to-AMB interface, and subsequent stresses can shear the gate wirebond.
The double-stitch gate wirebond provides two advantages:
First, having a double-stitch gate wirebond provides a redundant connection. If one of the stitch bonds fails, the second can retain the electrical gate connection.
Second, the "caterpillar" loop in the double-stitched gate wirebond provides a cavity where the electronic mold compound fills this space under the gate loop. This effectively provides a mold-locking feature to reduce the chance of mold delamination from the AMB surface. By reducing the chance of delamination, this further reduces the chance of additional stress on the gate wirebond, along with reducing the opportunity for moisture and other contamination to ingress at the mold-AMB interface.
Wafer and epitaxy advances enable affordable SiC power semiconductors
SiC is a far more challenging substrate than silicon at every stage of component manufacture, from ingot or boule production through wafering, epitaxy, lithography, and dicing. Understanding and overcoming these challenges has defined technology’s journey from research to commercial availability. The technical justifications for adopting SiC in high-efficiency converters and drives are clear.
But what about the economic argument? In this EEPower article, Tony Witt and Timothy Han from SemiQ discuss all the challenges and improvements in production processes, equipment, and practice.
SK Keyfoundry expands SiC expertise with SK Powertech acquisition
SK keyfoundry (SK?????) has announced its decision to acquire a 98.59% stake in SK Powertech from SK Inc. for 25 billion won. This acquisition, set to be completed in the first half of this year pending regulatory approvals, marks a significant step for SK Keyfoundry in its quest to become a leader in the next-generation compound semiconductor business.
SK Keyfoundry, a 200-mm (8-inch) foundry that had been spun off from Magnachip Semiconductor in September 2020, became a subsidiary of SK hynix in August 2022. SK Powertech, formerly known as Yes Power Technics, was acquired by SK Inc. in 2022 and is renowned for its expertise in designing and manufacturing SiC-based power semiconductors.
The acquisition comes at a time when the 200-mm foundry market is experiencing improved utilization rates, presenting an opportune moment for SK Keyfoundry to enhance its competitiveness. By integrating SK Powertech’s SiC technology with its mass production capabilities, SK Keyfoundry aims to create significant synergies.
Team at University of Arkansas wins DOE's SiC packaging contest
A team of the University of Arkansas Power Group was a phase one winner in the U.S. Department of Energy (DOE) 's Silicon Carbide Packaging Prize, a challenge to design the next generation of packaging for semiconductor devices.
Existing technology for packaging SiC often keeps the devices from reaching their full potential. The design proposed by the U?of?A team embeds the SiC chip in low-temperature co-fired ceramic (LTCC) that allows the device to handle nearly 10 MW with higher temperatures in a package small enough to fit in the palm of a hand. The design also uses an innovative parallel structure that improves performance.
As first phase winners, the U?of?A team will receive $50,000 to build a prototype of their design.
Review of electrically active defects in 3C, 4H, and 6H SiC polytypes
This paper from Ivana Capan at the Ru?er Bo?kovi? Institute aims to critically review electrically active defects studied by junction spectroscopy techniques (deep-level transient spectroscopy and minority carrier transient spectroscopy) in the three most used SiC polytypes: 3C-SiC, 4H-SiC, and 6H-SiC.
Given the dominant role of SiC in power electronic devices, the focus is strictly on electrically active defects that influence material performance and device reliability. The most prevalent defects in each polytype and their effects on electrical properties are examined. Additionally, recent advancements in defect characterization and defect engineering will be highlighted, emphasizing their impact on improving SiC-based device performance.
The paper also addresses the main challenges that continue to hinder the broader adoption of SiC, such as defect-related limitations in carrier lifetime and doping efficiency. Furthermore, beyond the well-established applications of SiC in power electronics and high-temperature environments, lesser-known niche applications are explored, showcasing the material’s versatility in emerging fields.
Ivana Capan. 2025. "Electrically Active Defects in 3C, 4H, and 6H Silicon Carbide Polytypes: A Review" Crystals 15, no. 3: 255. https://doi.org/10.3390/cryst15030255
Associate Professor, Advanced Semiconductor Lab at KAUST | (Ultra)wide Bandgap Semiconductor and 3D Stacking
1 小时前Thank you for highlighting our review paper on gallium oxide vertical diodes! Ralf Higgelke