Ralf’s GaN & SiC News (November 2, 2023)

Welcome to the latest edition of my newsletter on and. If you want to contribute, please reach out to me via [email protected]

Breaking News: Power Integrations Releases 1250-Volt GaN Switcher IC

With the INN3629C-H606 , Power Integrations released the world’s highest-voltage, single-switch GaN power supply IC from the InnoSwitch3-EP family, featuring a 1250-volt PowiGaN switch. This family of off-line CV/CC QR flyback switcher ICs feature synchronous rectification, FluxLink safety-isolated feedback, and an array of switch options: 725 V silicon, 1700 V silicon carbide, and PowiGaN in 750 V, 900 V, and now 1250 V varieties.

The switching losses for the 1250 V PowiGaN technology are less than a third of that seen in equivalent silicon devices at the same voltage, as the company said. This results in power conversion efficiency as high as 93% – enabling highly compact flyback power supplies that can deliver up to 85?W without a heatsink.

“Our ongoing development of higher voltage GaN technology, illustrated here by our new 1250 V devices, extend the efficiency benefits of GaN to an even wider range of applications, including many currently served by silicon-carbide technology,” said Radu Barsan , Vice President of Technology.

Gallium Nitride News

History Lesson on GaN and Outlook on GaN in India from Umesh Mishra

Transphorm Inc. 's Co-Founder and CTO Umesh Mishra sat down with Dr. Satya Gupta for VLSI Society of India (VSI) ’s newest episode of “Discussion on Chips" talking about Compound Semiconductors: GaN & SiC.

Tune in for a deep dive into the history of GaN, GaN and SiC technologies, the global landscape and rapid market growth potential, demanding end application requirements, and the importance of semiconductor manufacturing for India and the India Semiconductor Mission .

Really worth watching!

Women in GaN feat. Tamara Baksht and Giorgia Longobardi

As part of an ongoing EE Times | Electronic Engineering Times series Diversity & Belonging in EE, Maurizio Di Paolo Emilio interviewed Tamara Baksht , CEO and co-founder of VisIC Technologies Ltd. , and Giorgia Longobardi , CEO of Cambridge GaN Devices Ltd . These two brilliant minds shared their thoughts on:

• What inspired you to focus on GaN technology and its potential in the power electronics industry?
• How do you envision GaN technology shaping the future of power electronics and its impact on various industries?
• How does your company differentiate itself in the GaN technology market, and what’s your vision for its growth and success?
• What is the biggest challenge you have faced in your career, and how did you overcome it?
• What role does GaN technology play in achieving sustainability and reducing energy consumption in various industries?
• Can you share any insights or advice for aspiring entrepreneurs or professionals interested in the field of GaN technology and its applications?

Really worth reading!

Vermont Designated as GaN Tech Hub by the Biden-Harris Administration

As part of President Ali M. ’s Investing in America agenda, the U.S. Department of Commerce ’s U.S. Economic Development Administration (EDA), announced the designation of 31 Tech Hubs in regions across the country. This is the first phase of the new Tech Hubs program , which is an economic development initiative designed to drive regional innovation and job creation by strengthening a region’s capacity to manufacture, commercialize, and deploy technology that will advance American competitiveness. The designated Tech Hubs can now apply to receive between $40 million and $70 million each for implementation funding, totaling nearly $500 million.

The Advancing Gallium Nitride Tech Hub, led by the University of Vermont , seeks to innovate GaN manufacturing. This Tech Hub will leverage previous investments in GaN technology, regional physical assets, and technical workforce development programs to boost GaN manufacturing through technology innovation and prototype demonstrations. The Advancing GaN Tech Hub will further develop semiconductor technological applications—including high-power, energy-efficient systems, 5G/6G cellular base stations, and electrification of military fleet vehicles—bolstering national security and defense priorities.

Floating Capacitor Integrated DAB for Single-Phase, Single-Stage PFC in Wireless Battery Charging Application

Researchers from IKERLAN , and Universidad Politécnica de Madrid introduced a novel active power decoupling topology called Floating Capacitor Integrated Dual Active Bridge (FCI-DAB) for single-phase, single-stage AC-DC solutions. The main point of the circuit is an active energy buffer that compensates for the power fluctuation at double the grid frequency. The power decoupling filter is composed of a floating capacitor and a full bridge; and is connected to the high-frequency link of a resonant DAB|AC|-DC converter.

Compared to state-of-the-art two-stage solutions, it dispenses with the bulky electrolytic storage capacitor, with high ESR and low reliability, whose function is to create a constant DC bus. Unlike typical single-stage converters, filtering the fluctuating instantaneous power in the primary side of the converter brings advantages such as reducing the RMS current in the secondary side of the circuit, which results in a 50% savings in the secondary-side resistive conduction losses. This is considered a key point, especially in EV wireless battery charging applications, facilitating the refrigeration of the secondary-side circuit that is located onboard the vehicle.

The FCI-DAB concept is verified by experimental results, obtained from a GaN-based IPT 1.5 kW battery charger, with 93% of efficiency and PF = 0.99.

Itziar Alzuguren Almorza , Asier Garcia Bediaga , Ander Avila , Alejandro Rujas and Miroslav Vasic , "Floating Capacitor Integrated DAB for Single-Phase, Single-Stage PFC in Wireless Battery Charging Application," in IEEE Open Journal of Power Electronics, vol. 4, pp. 727-739, 2023, doi: 10.1109/OJPEL.2023.3313314.

Robust Avalanche in 1.7 kV Vertical GaN Diodes with a Single-Implant Bevel Edge Termination

Researchers from the Center for Power Electronics Systems, Virginia Tech , and 晶湛半导体 , demonstrate a novel junction termination extension (JTE) with a graded charge profile for vertical GaN p-n diodes. The fabrication of this JTE obviates GaN etch and requires only a single-step implantation. A bi-layer photoresist is used to produce an ultra-small bevel angle (～0.1°) at the sidewall of a dielectric layer. This tapered dielectric layer is then used as the implantation mask to produce a graded charge profile in p-GaN.

The fabricated GaN p-n diodes show a breakdown voltage (BV) of 1.7?kV (83% of the parallel-plane limit) with a positive temperature coefficient, as well as a high avalanche current density over 1100?A/cm2 at BV in the unclamped inductive switching test. This robust avalanche is ascribed to the migration of the major impact ionization location from the JTE edge to the main junction. This single-implant, efficient, avalanche-capable JTE can potentially become a building block of many vertical GaN devices, and its fabrication technique has wide device and material applicability.

Ming Xiao , Yifan Wang , Ruizhe Zhang , Qihao Song , Matthew Porter, Eric Carlson , Kai Cheng , Khai Ngo, Yuhao Zhang , "Robust Avalanche in 1.7 kV Vertical GaN Diodes with a Single-Implant Bevel Edge Termination," in IEEE Electron Device Letters, vol. 44, no. 10, pp. 1616-1619, Oct. 2023, doi: 10.1109/LED.2023.3302312.

Silicon Carbide News

GlobalWafers Enters SiC Substrate Business with Novel Crystal Growth Process

A new player enters SiC substrate business: GlobalWafers Co., Ltd. Doris Hsu, chairwoman of Taiwan-based silicon wafer supplier, said the company has independently developed the technology needed to produce high-quality 200-mm SiC wafers and expects to roll out small-scale production by the fourth quarter of 2024.

Usually, SiC crystal growth presents challenges due to the need for growth in extremely high-temperature sealed environments. Faced with that difficulty, GlobalWafers independently designed and developed a technology – a SiC-specific physical vapor transport method grower (PVT) – to reduce crystal growth costs while achieving higher material quality control.

Hsu said that while 150-mm SiC wafers are currently the mainstream, the development of 200-mm wafers has been “faster than she expected two years ago.” She estimated that production will ramp up in the fourth quarter of 2024 and accelerate further in 2025, with the production of 200-mm substrates surpassing that of 150-mm substrates in 2026.

When asked whether the production of SiC wafers will be mainly undertaken in Taiwan or at multiple sites, the chairwoman said currently the front-end production (crystal growth and processing) is located in Taiwan, and back-end production (epitaxy process) in the U.S. However, in the long run, she believes production will be further broken down, with multiple countries as processing sites, including in Japan or Europe, Hsu said.

CHESS-MOS: Seamless Stacking of 4H-SiC and 3C-SiC to Reduce Power Losses

A team of researchers at Tohoku University has succeeded in fabricating a 3C-SiC and 4H-SiC hybrid structure substrate using the Simultaneous Lateral Epitaxy (SLE) method. The new power semiconductor device called CHESS-MOS (Cubic and Hexagonal Epitaxially Stacked SiC MOSFET) was invented and patented by CUSIC Corporation (Sendai, Japan). Here, 3C-SiC crystals are grown on the top of the 4H-SiC basal plane extending from the 4H-SiC substrate during the epitaxial growth of SiC, and the 3C-SiC crystals are also extended along the 4H-SiC basal plane. A stacked structure is formed where 3C-SiC and 4H-SiC are clearly divided into upper and lower layers with the basal plane as the boundary.

SNDM (Scanning Nonlinear Dielectric Microscopy Method) demonstrated that the density of a 3C-SiC surface can be significantly reduced to less than 1/200 of that of a 4H-SiC surface. These results not only significantly improve the long-term reliability of SiC power MOSFET devices, but also reduce power loss by more than 30%. This might make a significant contribution to both higher performance and new functions of systems using SiC power semiconductor devices and energy conservation.

The research results were presented at the International Conference on Silicon Carbide and Related Materials (ICSCRM2023).

Fraunhofer ISE Presents SiC-Based Medium-Voltage String Inverter

In the MS-LeiKra project, Fraunhofer-Institut für Solare Energiesysteme ISE , in collaboration with Siemens Energy and SUMIDA CORPORATION , has developed an inverter that enables the output voltage to be increased to the medium-voltage range (1,500 V) at 250 kVA. The key to this is the use of SiC semiconductors, which have a higher blocking voltage. The research team has also implemented a more efficient cooling concept using heat pipes, which reduces the amount of aluminum required. Having fed power into the medium-voltage grid successfully, the research team is now looking for solar farm developers and grid operators to test the power plant concept in the field.

An average photovoltaic power plant requires dozens of kilometers of copper cables. Increasing the voltage generates significant savings potential: At today’s possible output voltage of 800?V (AC), a 250?kVA string inverter requires cables with a minimum cross-section of 120?mm2. By increasing the voltage to 1,500?V (AC), the cable cross-section can be reduced to 35?mm2. This in turn cuts copper consumption by around 700?kg per kilometer of cable.

Besides photovoltaics, moving beyond low voltage is also of interest for other applications, such as wind turbines, where the growing system capacities also require cables with large cross sections. The same is true for the charging infrastructure for large electric vehicles and vehicle fleets, and for industrial grids, where medium-voltage inverters could save a lot of material if cable cross sections could be reduced.

“Our resource analyses show that in the medium term, the electrification of the energy system will lead to copper becoming scarce. Increasing the voltage allows us to save valuable resources,” says Prof. Dr. Andreas Bett , Director of the Fraunhofer ISE.

Microchip Opens Automotive Technology Center in Detroit

Microchip Technology Inc. announces the expansion of its Detroit Automotive Technology Center in Novi, Michigan. The 24,000-square-foot facility is the destination for automotive clients to explore new technologies and meet with technical experts to get support for their end applications and designs. The company has more than doubled its lab space, including the addition of new labs that focus on high-voltage and E-Mobility applications.

“The new high-voltage lab will help our automotive customers develop systems using our reference design platforms and analog, digital control, and power solutions,” said Clayton Pillion , vice president of Microchip’s silicon carbide business unit.

Multichannel Measurement for SiC Inverter Voltage Waveforms

Research and development using SiC power devices is proving to be immensely important in the design and creation of significant energy-saving instruments. Now that it has progressed from the R&D stage to practical use, engineers are adopting SiC power devices in the production of motor drive inverters for railways and EVs.

To best utilize SiC devices for improved energy efficiency in equipment, it is important to optimize the internal device peripheral circuits in the inverter according to the device characteristics.

In both the R&D and evaluation stages, this means accurately measuring surge voltage, switching time, and high-speed changing voltage #signals at multiple locations is the priority.

How can this be done? Check out the application note from Yokogawa Test&Measurement .

Miscellaneous News

Wide-Bandgap Semiconductors at IEDM 2023

At the 69th annual IEEE International Electron Devices Meeting (IEDM) , which will be held in San Francisco Dec. 9-13, two sessions dealing with advances in power and wide bandgap devices that may interest your readers.

Session #9 on Monday, Dec. 11 is GaN Power Devices Integration . It features describing advancements in GaN power electronic devices and integration technology.

• 英飞凌 will outline the role that the latest power semiconductor technologies and circuits play in achieving a sustainable energy future.
• 香港科技大学 will discuss a novel GaN/SiC hybrid field-effect transistor that can harness the complementary merits of GaN and SiC.
• China’s Southern University of Science & Technology will detail a bipolar p-FET device with enhanced conduction capability.
• 北京大学 will discuss achieving a larger gate swing and enhanced threshold voltage stability of GaN HEMTs by using a metal/insulator/p-GaN structure.
• China’s 东南大学 will report on monolithically integrated GaN half bridges on sapphire
• 北京大学 will also report on monolithically integrated GaN half bridges but on Si substrates.
• 英特尔 will showcase the industry’s first CMOS “DrGaN” technology, fabricated in a 300 mm GaN-on-Si process containing enhancement-mode GaN MOSHEMT with 3D monolithic integration of Si PMOS.

Session #26 on Tuesday, Dec. 12 is Recent Advances in Wide Bandgap Materials and Devices for Power Electronics . This session features six papers describing recent advances in wide bandgap (WBG) materials and devices for power electronics.

• 北京大学 will demonstrate a 6.5 kV E-mode active-passivation p-GaN gate HEMT on a sapphire substrate with ultralow dynamic Ron.
• Toyota Motor Corporation will detail polarization engineering in AlSiO/p-GaN MOSFETs using AlN interlayers formed by PEALD. Channel mobility of over 300 cm2/V?s was achieved.
• 名古屋大学 (Nagoya University) will demonstrate AlN-based vertical p-n diodes on an AlN bulk substrate with dopant-free distributed-polarization doping. Clear rectification characteristics with a record breakdown field of 7.3 MV/cm was achieved.
• Hitachi Energy will report the first demonstration of 6.5 kV-class SiC trench-etched double-implantation (TED) IGBTs.
• Virginia Tech will describe 2 kV & 0.7 mΩ?cm2 vertical p-NiO/n-Ga?O? superjunction SBDs.
• 日本早稻田大学 will report on diamond p-MOSFETs with oxidized silicon termination. The device achieved channel mobility over 150 cm2/V?s and Vth higher than 3 V, allowing normally-off operation for the power IC.

Pie Chart of the Week: Power Semiconductor Manufacturer Landscape in 2027

In his recent poll, Alexey Cherkasov asked the community to share their feeling on how the situation in the power semiconductor industry will look like by 2027. About a year ago, he published research on the global power semiconductor manufacturers landscape. The geographical split looked like this:

• Asia – 57%
• Europe – 23%
• North America – almost 19%
• Rest of the world – a bit over 1%

Right now, the picture already looks different. And it’s nice to see that for the most part, the industry colleagues also expect the situation to change by 2027. It certainly will.

Reasons for that:

• More mergers and acquisitions within the industry
• Supply chain will be changing in many ways (Tier-1 and OEMs changing their strategies, etc.)
• Many power semiconductor start-ups that were launched during the past 2-3 years will not survive - market competition is getting tougher every year