Ralf’s GaN & SiC News (February 29, 2024)

Welcome to the latest edition of my newsletter on Silicon Carbide and Gallium Nitride. If you want to get covered, please reach out to me via [email protected]

APEC News

This week, the APEC Applied Power Electronics Conference and Exposition took place in Long Beach, California. Here are some of the new WBG products released there.

• Power Integrations announced the InnoMux-2 family of single-stage, independently regulated multi-output offline power-supply ICs. InnoMux-2 ICs consolidate AC-DC and downstream DC-DC conversion stages into a single chip, providing up to three independently regulated outputs for use in white goods, industrial systems, displays, and other applications requiring multiple voltages. Efficiency is aided by the ICs’ 750?V PowiGaN transistors, zero-voltage switching (without an active clamp), and synchronous rectification.
• Innoscience has launched a new 100-V bidirectional member of the company’s VGaN IC family. The INV100FQ030A can be employed to achieve high efficiency in 48-V or 60-V battery management systems (BMS), as well as for high-side load switch applications in bidirectional converters, switching circuits in power systems, and other fields. Such devices are ideal for applications like home batteries, portable charging stations, e-scooters, e-bikes, etc. The VGaN IC supports two-way pass-through, two-way cut-off, and no-reverse-recovery modes of operation. Devices feature a low gate charge of 90?nC, ultra-low dynamic on-resistance of 3.2?mΩ, and 4x6mm package size.
• Cambridge GaN Devices Ltd has introduced new reference designs that address the industrial market. With a power density of 23?W/in3 (1,4?kW/Liter), a 350?W PFC/LLC reference design has an average efficiency of 93% and a no-load power consumption of 150?mW. The CrM Totem Pole PFC + Half-Bridge LLC PSU has been realized using a 650 V/55 mΩ H2 series ICeGaN technology and delivers 20?V/17.5?A output.
• 英飞凌 has introduced the 750?V G1 discrete CoolSiC MOSFET to meet the increasing demand for higher efficiency and power density in industrial and automotive power applications. The product family includes both industrial-graded and automotive-graded devices that are optimized for totem-pole PFC, T-type, LLC/CLLC, dual active bridge (DAB), HERIC, buck/boost, and phase-shifted full bridge (PSFB) topologies. With an R(DS(on)) portfolio ranging from 8 to 140?mΩ at +25?°C, this product family meets a wide range of needs. The G1 for automotive applications comes in QDPAK TSC (Top-Side Cooling), D2PAK-7L, and TO-247-4 packages, while for industrial applications, QDPAK TSC and TO-247-4 packages are offered.

Silicon Carbide News

Amperesand raises $12.45M for SiC-based solid-state transformers

Amperesand , a new grid infrastructure company founded by industry veterans from 阿西布朗勃法瑞公司（ABB） , 通用电气 , 西门子 , and 维斯塔斯 , has announced seed financing of $12.45 million. Xora Innovation and Material Impact co-led financing with participation from TDK Ventures and Foothill Ventures .

The funding will help the company roll out infrastructure solutions powered by solid-state transformer technology. The aim is to facilitate bidirectional energy flow, intelligent monitoring, and energy management with native integration of mixed AC/DC systems, to enable the rapid adoption of EV fast charging, energy storage, and renewable energy systems. The SiC-based technology has already been tested on the Singapore grid at a 1.5 MW scale through a 7-year research program executed by the Energy Research Institute at 新加坡南洋理工大学 .

Performance analysis of bipolar SiC devices for grid-level converters

Recent commercialization of SiC bipolar devices, including SiC BJT, SiC MPS diode, and SiC PiN diodes, have enabled potential candidates to replace their unipolar SiC counterparts. However, the prospects of 4H-SiC power bipolar devices still need further investigation.

This doctoral thesis from 沈诚俊 at the 英国布里斯托大学 compares the static and dynamic performance and reliability of commercial bipolar SiC devices including SiC BJT, SiC MPS diode, and SiC PiN diode and their similarly rated (15 kV) silicon counterparts mainly using experimental measurements.

Chengjun Shen, Analysis of performance of SiC bipolar semiconductor devices for grid-level converters

LPO announces conditional commitment to SK Siltron CSS to expand American manufacturing of SiC wafers

Today, the U.S. Department of Energy (DOE) ’s Loan Programs Office | U.S. Department of Energy (LPO) announced a conditional commitment to SK siltron css for a $544 million loan to expand American manufacturing of SiC wafers for EV power electronics. This project reinforces President Joe Biden’s Investing in America agenda to onshore and re-shore domestic manufacturing technologies.

If finalized, the LPO-financed project will help SK Siltron CSS leverage its two existing Michigan manufacturing plants to address this market gap. Historically, much of the research and development for the manufacturing process has occurred at the company’s facility in Auburn, Michigan. The expanded Bay City plant will use technology developed in Auburn to create the high-quality wafers needed to realize President Biden’s EV goals.

The company will partner with Delta College , less than a mile from the project site, through the Michigan New Jobs Training Program to train local workers for success in SiC wafer manufacturing. In addition, LPO works with all borrowers to create quality jobs during construction, operations, and throughout the life of the loan and works to ensure borrowers develop and ultimately implement a strong Community Benefits Plan .?

Aehr receives $23 Million in new follow-on orders for wafer-level test and burn-in of SiC Devices

Aehr Test Systems has received new follow-on orders totaling $23 million from existing customers for FOX wafer-level test and burn-in products to be used for the production and engineering qualification needs of SiC devices. Customer-requested ship dates for these orders range from immediate shipment through the end of Aehr’s current fiscal year, which ends May 31, 2024.

The FOX-XP and FOX-NP systems and proprietary WaferPaks are capable of functional test and burn-in/cycling of silicon carbide and gallium nitride power semiconductors, silicon photonics integrated circuits as well as other optical devices, 2D and 3D sensors, flash memories, magnetic sensors, microcontrollers, and other leading-edge ICs in either wafer form factor before they are assembled into single or multi-die stacked packages, or in singulated die or module form factor.

Job Exchange

• Senior R&D Manager in East Bay, San Francisco. Qualifications: Background in Power Electronics topologies and applications that implement Silicon Carbide, Gallium Nitride, or Silicon Devices.

• Quality Assurance Engineer for Power Semiconductors at ROHM Semiconductor Europe in Willich, North Rhine-Westphalia, Germany

Gallium Nitride News

GaN Patent War: ITC investigative staff sides with EPC against Innoscience

The evidentiary hearing in the U.S. International Trade Commission (ITC) investigation EPC - Efficient Power Conversion against Innoscience is scheduled for this week. As is typical in such investigations, the complainant (EPC), the respondent (Innoscience), and the Investigative Staff of the ITC were required to file pre-hearing briefs setting forth their respective positions on, among other things, patent infringement and validity.

February 23, 2024, the Staff publicly released its pre-hearing brief. As David Radulescu, Ph.D. explains, this can only be characterized as a massive blow to Innoscience. The ITC Staff’s brief explains that it:

1. “expects the evidence to show that there has been a violation of Section 337 as to the '294 patent, but not as to the '508 patent.”?In other words, the Staff “expects” the evidence to show that the “asserted claims of the ’294 patent are infringed” (while the single asserted claim of the ’508 patent is not infringed).
2. “expects that Innoscience will be unable to show by clear and convincing evidence that any of the asserted claims are invalid.”
3. “believes that the appropriate remedy will be a limited exclusion order and cease and desist orders.”

Of course, these are “pre-hearing” positions, and much will depend on what happens at the evidentiary hearing this week, in addition to how well the parties do in “post-hearing” briefs due to be filed next month. The Administrative Law Judge will make his own determination as to whether EPC or Innoscience prevails based on all the evidence and the law.

Nonetheless, this news is not good news for Innoscience and its ability to continue to sell and import its accused e-HEMT devices (650 and 100 V) into the United States. As previously reported, EPC withdrew two of its four asserted patents in the months leading up to the hearing. The Administrative Law Judge is expected to issue his Initial Determination in June 2024 with the Target Date for completion of the Investigation presently set for Oct 3, 2024.

Taiwan grants $5 million for GaN-on-QST

The Ministry of Economic Affairs (Taiwan) held the first final review meeting for the A+ Enterprise Innovation R&D Quenching Plan for 2024, an important step in strengthening the country's leadership in semiconductor innovation. The “High-power and high-efficiency GaN-on-QST component and process technology development project” was granted a NT$150 million ($5 million) subsidy as one out of four approved projects.

This project, led by Vanguard International Semiconductor Corporation (VIS), is focused on gallium nitride epitaxial crystal growth on 200-mm QST substrate from Qromis, Inc. and intends to lead the development of state-of-the-art compound semiconductor technology. VIS is the first semiconductor foundry service to provide this platform.

In an interview with Power Electronics News , Shyh-Chiang Shen , GaN program director at VIS, shed light on the company’s strategic approach within Taiwan’s semiconductor ecosystem. He stressed VIS’s commitment to advancing the development and market acceptance of the revolutionary 1,200-V GaN-on-QST technology, particularly within the automotive and industrial sectors.

Alex Lidow and Steve Sandler on power electronics and gallium nitride

Last week, I presented here the new high-speed transient load for 2000 A from Picotest featuring the GaN devices from EPC - Efficient Power Conversion . In this video, Alex Lidow , co-founder and CEO of EPC, and Steven Sandler , founder and CEO of Picotest, chatted about the challenges of bringing high power into a small space. Steve Sandler is showing some crazy stuff! Great cinema for engineers!

Recent developments and prospects of fully recessed MIS gate structures for GaN-on-Si power transistors

Fully recessed MIS gate GaN power transistors or MOSc-HEMTs have gained interest as normally-off HEMTs thanks to the wider voltage swing and reduced gate leakage current when compared to p-GaN gate HEMTs. However, the mandatory AlGaN barrier etching to deplete the 2DEG combined with the nature of the dielectric/GaN interface generates etching-related defects, traps, and roughness. As a consequence, the threshold voltage can be unstable, and the electron mobility is reduced, which presents a challenge for the integration of a fully recessed MIS gate. Recent developments have been studied to solve this challenge.

In this paper, a team of researchers from the Université Grenoble Alpes , CEA-Leti , and the CNRS discusses developments in gate recess with low-impact etching and atomic layer etching (ALE) alongside surface treatments such as wet cleaning, thermal or plasma treatment, all in the scope of having a surface close to pristine. Finally, different interfacial layers, such as AlN, and alternative dielectrics investigated to optimize the dielectric/GaN interface are presented. Finally, a better understanding of gate–trench sidewall quality is needed to fully quantify their impact on device properties.

Pedro Fernandes Paes Pinto Rocha , Laura V. , Patricia Pimenta Barros , Simon RUEL , René ESCOFFIER , and Julien Buckley . "Recent Developments and Prospects of Fully Recessed MIS Gate Structures for GaN on Si Power Transistors" Energies 16, no. 7: 2978. https://doi.org/10.3390/en16072978

Analog Devices webinar: Unleash the benefits of GaN technology with advanced GaN controllers and gate drivers

The superior switching performance of GaN FETs enables higher power density for space-constrained applications. Solutions using GaN technology have new challenges to ensure robust operation. In this webinar, Tae Han and Nixon Mathew explore how 亚德诺半导体 ’ GaN power solutions simplify the design process and enable energy-efficient performance.

?Attendees will learn:

• How ADI GaN solutions can optimize power conversion efficiency
• How GaN FETs are controlled compared to traditional Si MOSFETs
• Key features that ensure robust and reliable operation of GaN transistors

Date: March 06, 2024

Time: 8:00 am PDT | 11:00 am EDT | 17:00 CEST

Infineon’s predictions and anticipations for GaN in 2024

GaN Systems, now Infineon Technologies Canada Inc. , used to publish yearly its predictions and anticipations for GaN. Also as part of 英飞凌 , they continue this tradition. Here now comes the issue for 2024.

The predictions in a nutshell:

• Growing sustainability concerns drive global surge in e-mobility
• AI surge of power usage leads to a growing need for energy-efficient solutions
• Technology breakthroughs will unleash the long-promised potential of solar energy and storage for homes, businesses, and the power grid
• The end-user experience will transform across consumer and commercial markets

For a deeper understanding of what 2024 holds for GaN power semiconductors and what Infineon anticipates, download the eBook .

Effects of the LPCVD gate dielectric deposition temperature on GaN MOSFET channels and the root causes at the SiO? -GaN interface

MOSFETs have been fabricated on 150 mm heteroepitaxial GaN-on-Si wafers. This work from researchers from Bosch Research and the University of Bremen focuses on the significant impact of the gate dielectric deposition temperature and investigates the resulting transistor channel characteristics, the gate dielectric robustness, and the underlying physical mechanisms. It is shown that varying the SiO? gate dielectric deposition temperature below and above the GaN decomposition temperature resulted in channel mobility of 17 to 55?cm2/(V?s) at threshold voltages of 8.0 to -3.2 V, respectively.

Gate dielectric robustness and reliability studies demonstrated that oxide charging effects and lifetime also depend on the deposition temperature. In addition to the electrical measurements, secondary ion mass spectrometry (SIMS) and transmission electron microscopy (TEM) are used to identify root causes. It is found that various defect types, i.e., chargeable interface states, fixed oxide charges, diffusion of foreign atoms, vacancies, and surface roughness depend on the deposition temperature. In particular, SIMS measurements revealed a temperature-dependent diffusion of potential n-type dopants, originating from the SiO? deposition, into the p-type channel region. As a further tuning parameter of threshold voltage and channel mobility, the influence of the magnesium doping concentration of the p-body layer is investigated.

Mirjam Henn , Christian Huber , Dick Scholten and Nando Kaminski , "Effects of the LPCVD Gate Dielectric Deposition Temperature on GaN MOSFET Channels and the Root Causes at the SiO?-GaN-Interface ," in IEEE Transactions on Electron Devices, doi: 10.1109/TED.2023.3347208

Miscellaneous News

SiC is state of the art in EVs, but vertical GaN could be the next big thing, Bosch and ORNL say

In an article on SAE International , Vishnu Medisetty , director of power electronics for Bosch in North America, confirms that SiC devices are the mainstay of the company’s power-electronics portfolio.

“We are already on our second generation [of SiC],” Medisetty acknowledged. “We are working towards our third generation and there are generational improvements in the efficiency of the devices. So, the device efficiency improves – but also, there's a huge cost driver behind EV applications. What we look at is trying to reduce the cost of the power-electronic device, be it a charger converter or be it an inverter that is driving the motor. We try to reduce the size of the die, the chip, extract more current out of it, need less cooling for it.”

“There are no gallium-nitride vertical devices available,” Burak Ozpineci , section head of the Vehicle and Mobility Systems Research Section at Oak Ridge National Laboratory , said. “The challenge with them is they’re usually low-voltage, low-current right now. In a low-power onboard charger, or if you’re looking at other DC/DC converters — again, low-voltage, low-power — you can use GaN, which will beat SiC at the power level. But the vertical GaN devices, which actually will have better properties than SiC, are not ready yet — and they might not be ready for another ten years.”

Bosch’s Medisetty agreed, saying that for now, gallium-nitride doesn’t have the performance needed by the transportation sector. “[GaN devices] are quite a bit lower-voltage, not readily suitable for automotive electromobility applications, but there are other gallium nitride approaches which are more similar to silicon-carbide devices,” he said. “These have higher voltages, are more robust and more suited for electromobility applications.

“Bosch is working extensively on gallium nitride that is more suitable for electromobility applications,” he added. “We see a potential for it, but it's still further out and there is a lot more ground to be covered on silicon-carbide optimization. There're generations before we get there.”

Compound Semiconductor Week in June at Lund University

On June 3-6, 2024, the Compound Semiconductor Week (CSW) takes place at 瑞典兰德大学 in Sweden. It is the premier conference in the areas of science, technology and applications of compound semiconductors. The conference addresses compound semiconductors from fundamentals to applications in a wide perspective. CSW covers new developments in materials and physics while simultaneously addressing applications in electronics, optoelectronics, and new fields. With its annual coverage, CSW is a forum for the latest developments in this important field.

In the plenary the following keynotes are already confirmed:

• “Connecting the Dots - Heterogeneous Integration, III-V, and the Future of Connectivity” by Nadine Collaert , imec
• “Wide band gap materials and devices” by Srabanti Chowdhury , 美国斯坦福大学

WSTS says that WBG semiconductors increased their market share by 50% in 2023

In 2023, World Semiconductor Trade Statistics expanded into new wide bandgap semiconductor categories for power transistors and rectifiers. Showing significant growth, the SiC & GaN product share in the power transistor and rectifier market grew from about 10% in Q1 to 15% by Q4 of 2023.

Excitingly, in 2024, we will introduce further wide bandgap categories for MOSFET & IGBT modules. Stay tuned for more innovative developments!