Ralf’s GaN & SiC News (January 25, 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]
Breaking News: Hybrid transistor combines the best of GaN and SiC
What if you could combine GaN and SiC in a single device that minimizes the weaknesses of each and maximizes their strengths? That’s the question that drove a team of 16 researchers at 香港科技大学 and three other institutions in China. They finally claimed success by fabricating a transistor, which they call a hybrid field-effect transistor, or HyFET. They described their work in a paper presented at the IEDM Conference 2023.
The device uses a low-voltage, high-speed GaN transistor to control a high-voltage SiC JFET. In the HyFET, there’s a drain at the bottom of the device, connected to the substrate. Current flows upward through a SiC drift layer. However, the gate and source terminals are in a GaN transistor integrated directly above the SiC JFET, at the top of the device. So the current flowing through the SiC JFET is controlled by a gate and source terminals that are in the GaN part of the device.
The advantage here is that it is the GaN transistor, with its high electron mobility, that controls the switching of the combined device. Built on the foundation of the SiC JFET, with its large drift region, the combined device has the voltage-blocking capabilities of SiC. Testing indicated that the device largely fulfilled the researchers’ expectations.
One of the weaknesses of the HyFET is its specific on-resistance with around 50 mΩ?cm2. A state-of-the-art SiC or GaN transistor capable of blocking more than 600 volts can reach 2?mΩ?cm2. IEEE Fellow Debdeep Jena ( 美国康奈尔大学 ) noted that a potentially insurmountable obstacle for the HyFET is the rate of advancement of GaN devices. In the foreseeable future, he says, GaN will become so capable that it probably won’t require hybrid schemes to triumph. “The physics tells me that GaN is the winner in the long run,” he says. “I don’t want to take anything away from the HyFET paper. It’s a great paper. But whatever they have shown here will also be possible with gallium nitride in the future,” he concludes.
Jin Wei , Huaping Jiang, Qimeng Jiang, and Kevin J. Chen , "Proposal of a GaN/SiC Hybrid Field-Effect Transistor for Power Switching Applications," in IEEE Transactions on Electron Devices, vol. 63, no. 6, pp. 2469-2473, June 2016, doi: 10.1109/TED.2016.2557811.
Gallium Nitride News
Yole expects more M&As in the rapidly evolving power GaN ecosystem
In the power GaN industry’s second major acquisition in a year, following 英飞凌 ' purchase of Infineon Technologies Canada Inc. (former GaN Systems), US-based Transphorm Inc. is to be acquired by a subsidiary of 瑞萨电子 . The acquisition adds to the billions of dollars invested in the power GaN industry since 2019 through partnerships, the construction of facilities, and M&As. But what is driving this activity, and what does this new acquisition signal for the future of power GaN? Yole Group ’s experts Dr. Milan ROSINA and Taha Ayari, PhD provide their insights.
While the consumer industry has traditionally been the largest market sector in power GaN, the automotive market is set to experience the most significant growth in the next few years – Yole Group predicts the sector to be worth $504 million by 2028, growing at a 110% CAGR. The sector is attractive for players such as Renesas and Infineon Technologies because it experiences higher margins and ROIs than the consumer sector.
The trend toward more integrated systems is notable in electric vehicles in particular, where OEMs are moving from today’s 3-in-1 unit that integrates an EV drive motor, gearbox and inverter – to 5-in-1, or even 8-in-1 systems (Discover Yole Group’s article focused on 8-in-1 powertrain from BYD) that also include power electronics controls such as DC-DC converters and on-board chargers. This is where the major opportunity lies for GaN to offer a high level of perceived value in reducing system costs, weight, volume, and power losses.
Transphorm’s automotive-qualified GaN technology was mentioned explicitly by Renesas as a reason for its purchase, to enable the development of enhanced power solutions for EVs. This followed Renesas’ already strong ambition in targeting integrated power solutions for EVs with a recent partnership with Nidec, which will see the companies develop a 6-in-1 E-Axle.
But why did Infineon pay more than double the $339 million Renesas paid for Transphorm? Who will be the newcomers and the next acquisition targets in power GaN? Find out more in this article.
Are diamonds GaNs best friend?
Thermal management is critical in contemporary electronic systems, and integrating diamond with semiconductors offers the most promising solution to improve heat dissipation as diamond exhibits the highest thermal conductivity of all natural materials. However, developing a technique that can fully exploit the high thermal conductivity of diamond, withstand high-temperature annealing processes, and enable mass production is a significant challenge.
Researchers at Osaka Metropolitan University now have reported the successful transfer of AlGaN/GaN/3C-SiC layers grown on Si to a large-size diamond substrate is demonstrated, followed by the fabrication of GaN high electron mobility transistors (HEMTs) on the diamond. Notably, no exfoliation of 3C-SiC/diamond bonding interfaces is observed even after annealing at +1100?°C, essential for high-quality GaN crystal growth on the diamond.
The thermal boundary conductance of the 3C-SiC-diamond interface reaches around 55?MW/(m2?K), which is efficient for device cooling. GaN HEMTs fabricated on the diamond substrate exhibit the highest maximum drain current and the lowest surface temperature compared to those on Si and SiC substrates. Furthermore, the device thermal resistance of GaN HEMTs on the diamond substrate is significantly reduced compared to those on SiC substrates. These results indicate that the GaN/3C-SiC on diamond technique has the potential to revolutionize the development of power and radio-frequency electronics with improved thermal management capabilities.
Ryo Kagawa, Zhe Cheng, Keisuke Kawamura, Yutaka Ohno, Chiharu Moriyama, Yoshiki Sakaida, Sumito Ouchi, Hiroki Uratani, Koji Inoue, Yasuyoshi Nagai, Naoteru Shigekawa, Jianbo Liang, High Thermal Stability and Low Thermal Resistance of Large Area GaN/3C-SiC/Diamond Junctions for Practical Device Processes. Small 2023, 2305574. https://doi.org/10.1002/smll.202305574
Comparing Discrete and Integrated GaN Solutions
In addition to the widespread availability of discrete GaN HEMT devices, we are seeing the emergence of integrated GaN solutions from leading GaN manufacturers that build on the intrinsic benefits of GaN and have the potential to deliver even better performance.
But which way to go? Should engineers go for a discrete or an integrated GaN solution? In an article in Power Electronics News , Denis Marcon and Simon (Shuilin) Tian from Innoscience make a deep dive. The bottom line: Integrated solutions offer many benefits, including size and efficiency, yet discrete GaN solutions still provide the ultimate in design flexibility and may be the only available choice at higher powers until further paralleling of integrated devices is achieved.
Physical insights into trapping effects on vertical GaN-on-Si trench MOSFETs from TCAD
In this work, a team of researchers from the Università degli Studi di Modena e Reggio Emilia , Università degli Studi di Padova (UNIPD) / University of Padua , and Bosch Research reports on the physical insights into device performance improvements obtained during the development of vertical GaN-on-Si trench MOSFETs (TMOS’s) provided by TCAD simulations, enhancing the dependability of the adopted process optimization approaches.
Specifically, two different TMOS devices are compared in terms of transfer-curve hysteresis (H) and subthreshold slope (SS), showing a ≈ 75% H reduction along with a ≈ 30% SS decrease. Simulations allow attributing the achieved improvements to a decrease in the border and interface traps, respectively. A sensitivity analysis is also carried out, allowing to quantify the additional trap density reduction required to minimize both figures of merit.
Nicolò Zagni , Manuel Fregolent , Andrea Del Fiol, Davide Favero , Francesco Bergamin, Giovanni Verzellesi , Carlo De Santi , Gaudenzio Meneghesso , Enrico Zanoni , Christian Huber , Matteo Meneghini and Paolo Pavan . Physical insights into trapping effects on vertical GaN-on-Si trench MOSFETs from TCAD[J]. J. Semicond, 2024, 45(3): 032501. doi: 10.1088/1674-4926/45/3/032501
everything PE publishes list of top GaN transistors in 2023
In this article, everything PE has listed some interesting GaN transistors that were trending on the website:
1.2-kV vertical GaN JFET from NexGen shows no dynamic R(on) behavior
Dynamic ON-resistance (R(on)) or threshold voltage (V(th)) instability caused by charge trapping is one of the most crucial reliability concerns of some GaN HEMTs. It has been unclear if this issue can be resolved using an alternative GaN device architecture. This work of a team at the Center for Power Electronics Systems, Virginia Tech , and NexGen Power Systems answers this question by characterizing, for the first time, the dynamic R(on) and V(th) stability of an industrial vertical GaN transistor-NexGen’s 1200-V/70-mΩ fin-channel JFET, fabricated on 100-mm bulk GaN substrates.
A circuit setup is deployed for the in-situ measurement of the dynamic R(on) under steady-state switching. The longer-term stability of R(on) and V(th) is tested under the prolonged stress of negative gate bias and high drain bias. The vertical GaN JFET shows nearly no R(on) or V(th) shift in these tests, which could be attributed to the low defect density of the GaN-on-GaN homoepitaxial growth, the absence of electric field crowding near the surface, and the minimal charge trapping in the native junction gate. These results present a critical milestone for vertical GaN devices toward power electronics applications.
Xin Yang, Ruizhe Zhang, Bixuan Wang , Qihao Song , Andrew Walker , Subhash Pidaparthi , Cliff Drowley , Yuhao Zhang . "Dynamic RON Free 1.2-kV Vertical GaN JFET," in IEEE Transactions on Electron Devices, vol. 71, no. 1, pp. 720-726, Jan. 2024, doi: 10.1109/TED.2023.3338140.
Silicon Carbide News
领英推荐
Infineon and Wolfspeed expand and extend the multi-year SiC 150mm wafer supply agreement
英飞凌 and Wolfspeed announced the expansion and extension of their existing long-term 150mm wafer supply agreement, originally signed in February 2018. The extended partnership includes a multi-year capacity reservation agreement. It contributes to Infineon’s general supply chain stability.
“As the demand for silicon carbide devices continues to increase, we are following a multi-source strategy to secure access to a high-quality, global, and long-term supply base of 150mm and 200mm SiC wafers. Our prolonged partnership with Wolfspeed further strengthens Infineon’s supply chain resilience for the coming years,” said Jochen Hanebeck , CEO of Infineon.
“Industry estimates indicate demand for silicon carbide devices, as well as the supporting material, will grow substantially through 2030, representing a $20 billion annual opportunity. We are very pleased to continue our partnership with Infineon and to serve as a major supplier of silicon carbide wafers in the years ahead,” said Wolfspeed president and CEO Gregg Lowe .
Five companies control the SiC power market
The global power SiC device market is forecasted to grow to about USD 9 billion by 2028, a 31% increase over 2022, according to the 2023 edition of Yole Intelligence 's Power SiC Report. While automotive applications dominate the SiC market, other applications such as industrial, energy, and rail are adding to its growth momentum. But how does the market look?
Major players currently control more than 90% of the market, increasing competition. And a slowdown in progress could spell opportunities for followers. According to TrendForce Corporation , the top five SiC power semiconductor players in 2022 were dominated by 意法半导体 (36.5%), 英飞凌 (17.9%), Wolfspeed (16.3%), 安森美半导体 (11.6%), and ROHM Co., Ltd. (8.1%), with the remaining companies accounting for only 9.6%.
200-mm SiC substrates gaining traction
As stated by TrendForce 集邦科技 , 150-mm (6-inch) substrates currently hold up to 80% of the market share in the SiC industry, whereas 200-mm (8-inch) substrates only make up 1%. A key strategy to further reduce SiC device costs is to move to larger 200-mm substrates. Several major Chinese players – such as SEMISiC, 浙江晶盛机电股份有限公司 (JSG), Summit Crystal, Synlight Semiconductor, KY Semiconductor, and IV-SemiteC – are currently advancing the development of these larger SiC substrates. “This shift from the approximately 45% of total production costs associated with substrates is expected to facilitate the broader adoption of SiC devices and create a positive cycle for major companies,” TrendForce reported back in November 2023.
However, we’re not only seeing leaps being made by Chinese companies but also major international players. Just look at the recent movement from Infineon, onsemi, and Wolfspeed. With mass production applications planned to start before 2030, Infineon has already prepared the first batch of 200-mm wafer samples at its fab and intends to turn them into electronic samples shortly, as pointed out by TrendForce.
Peter Gammon offers independent SiC R&D services
PGC Consultancy provides essential services related to the development of next-generation SiC power devices. Peter Gammon ’s expertise spans:
Early-stage prototyping
With access to a highly flexible class 10,000 SiC research cleanroom, we help our customers develop new product ideas. PGC specializes in developing low-volume, early stage, and novel products that might be beyond the restrictive PDKs of pilot fabs.
Device optimizations and Digital Twins
PGC has the expertise to design SiC products that trade off and prioritize efficiency, cost, and reliability KPIs. We have developed our own devices and provided optimization advice to customers. They also have experience developing digital twins of commercial SiC products, producing models with matched electrical performance.
Sanan and Luminus partner on SiC power chip sales in the US
Sanan Semiconductor and Luminus Devices (both subsidiaries of Chinese LED giant 三安光电股份有限公司 ) have signed a deal that makes Luminus an exclusive sales channel in the Americas for power semiconductors. The companies say the partnership addresses long lead times for SiC wafers, Schottky diodes, and MOSFETs for customers in a wide range of power-related industries.
Sanan, having recently completed construction of a $2B Megafab in Changsha, China, intends to offer customers products and foundry services with aggressive lead times, as low as 8 weeks for most products. The capacity of the Megafab also positions Sanan as the largest vertically integrated SiC manufacturer in China, and the 3rd largest in the world. Sanan plans to focus on foundry services to support already established semiconductor companies that need a secure supply of SiC substrates, epi wafers, or bare die.
Sanan is already breaking ground on a mirror image of the Megafab next door which will more than double the capacity by early 2025. All of this is separate from the $3.2B SiC joint venture Sanan announced with 意法半导体 in 2023 in Chongqing, China.
"We are excited to leverage the well-established Luminus sales team in the Americas, including their regional manufacturers reps and distributors to deliver our wide bandgap technology and products to customers who have been suffering from limited allocation and long lead times in recent years," comments Tony Chiang, CEO of Hunan Sanan Semiconductor.
Noise propagation on gate drivers caused by near field coupling inside medium voltage converters
Unlike the converter-level noise emissions which can be regulated by certain EMI/EMC standards, the noise inside the power converter has no standard to follow. Moreover, even if a converter complies with certain standards at its terminals, it is not guaranteed to work without issues. Meanwhile, modern power converters consist of many auxiliary circuitries that are subject to malfunction due to the switching noise propagated inside of it. It is of great importance to study the mechanisms by which noise is induced on low-power logic circuitries, caused by the switching transient of the high-power main circuit power stage.
This presentation of He Song of Center for Power Electronics Systems, Virginia Tech ( CPES Achievements Showcase ) is a continuity of our previous work regarding the noise propagation inside the power converter, particularly noise induced on gate driver PCB traces caused by the fast switching of the main circuit via near fields. The noise at the input pins of the critical ICs is the point of interest. Based on the proposed generic methodology, a comprehensive near-field noise propagation model on PCB traces is proposed and verified experimentally, and the effects of both magnetic and electric near fields are studied. Factors that influence the noise coupling are also investigated.
Fuji Electric to invest 200 billion yen to strengthen also SiC capacity
According to Nikkei China, Fuji Electric Co., Ltd. will invest 200 billion yen (1,36 billion US Dollars) in the semiconductor field within three years from 2024 to 2026. The focus will be on power semiconductors used for EV power control, etc.
Specifically, the company will build a "pre-lithography process" production line at the Matsumoto Factory (Nagano Prefecture). Production of SiC power semiconductors using 200-mm wafers will begin after fiscal 2027. Furthermore. Fuji Electric plans to mass-produce SiC power semiconductors on 150-mm wafers at the Tsugaru Plant (Aomori Prefecture) starting in fiscal 2024.
Job exchange
Miscellaneous News
University of California Santa Barbara presents first N-polar InAlGaN HEMT
The University of California Santa Barbara has reported the first N-polar InAlGaN quaternary back barrier HEMT. The epitaxial structure for the HEMT was grown by metal-organic chemical vapor deposition (MOCVD) on 4°-miscut sapphire substrate. Such substrates are used to avoid hexagonal hillock defect formation, which commonly occurs in N-polar growth.
Room-temperature Van der Pauw Hall measurements gave a 2DEG sheet carrier density (ns) of 2.85×1013 cmˉ2, a mobility of 1048?cm2/(V?s), and a remarkably low sheet resistance of 179 Ω/square in the source-drain direction. The team comments: “We believe that the large 2DEG density is a result of the relatively thick channel and barrier layers, as well as the ionization of hole traps at the net negatively polarized barrier/buffer interface.”
Robert H. , Nirupam H. , Emre Akso, Ph.D. , Feng Wu , Christopher Clymore , Stacia Keller, James Speck, and Umesh Mishra , "First Demonstration of an N-Polar InAlGaN/GaN HEMT," in IEEE Electron Device Letters, doi: 10.1109/LED.2023.3346818.
Thanks, Ralf Higgelke we are excited for all the opportunities to come this year!