Tantalizing Potential for GaN in Electric Vehicle Power Electronics
Mar 24, 2023
As electric vehicle (EV) power electronics undergoes a paradigm shift towards wide bandgap (WBG) semiconductors, it is clear that silicon carbide (SiC) is becoming the material of choice, while gallium nitride (GaN) is often shoe-boxed into telecommunications or optoelectronics applications. In part, this is because SiC has the greatest thermal conductivity (of Si and GaN), which naturally lends itself to the high temperature, power, and voltage operation typical of an EV. Yet, GaN can still achieve double the thermal conductivity of Si and is superior to SiC in almost every other metric, from electron mobility and efficiency to breakdown voltage.
The problem is GaN power devices today are operating some two orders of magnitude worse than their bulk material properties, reflecting the tantalizing potential. The stakes are also high as EV markets grow rapidly and OEMs are looking to improve drive cycle efficiencies using the WBG power electronics commercially available today.
Material properties of GaN & SiC relative to Si. Source: IDTechEx
Indeed, the new IDTechEx report "Power Electronics for Electric Vehicles 2023-2033" covers adoption rates of SiC and GaN in electric vehicle inverters, onboard chargers (OBC) and converters. Market entry of GaN is predicted in the near future, and the report shows that YoY growth of SiC in EV markets will reach 79% in 2023 while the overall EV market has a 15% CAGR over the next ten years.
What's preventing GaN devices from tapping into this market? The crucial barrier is the material's production quality, which depends on the epitaxial substrate - GaN, SiC or Si. Since the primary source of material degradation are mismatches between the epitaxial growth and the substrate, the ideal case is homoepitaxy, or bulk GaN (GaN-on-GaN). Indeed, the knock-on effect on the performance when using silicon-based substrates is demonstrated by the blocking voltages achieved. Bulk GaN is 94kV, and SiC is 45kV, but GaN-on-Si, in volume production today, is around ~1kV because of mismatches, which is comparable to bulk silicon (Si). For a holistic view of the semiconductor supply chain, the new IDTechEx report "Semiconductors for Autonomous and Electric Vehicles 2023-2033" covers semiconductor trends and materials demand for electric vehicles, autonomous vehicles, battery management systems (BMS), radar, Lidar, infotainment and more.
As is often the case with emerging technologies, the adoption of the best technology, in this case, GaN-on-GaN, is limited by the high cost. Bulk GaN is only available in small wafer sizes, contributing to a cost of around 1000 times greater than Gan-on-Si. The next best choice is Gan-on-SiC, which yields lower mismatches but again has a cost of around two orders of magnitude greater. Using GaN for high voltage applications, EV inverters, for example, therefore require either improving mismatches between GaN-on-Si or achieving low-cost production of bulk GaN. Until this is achieved, SiC will remain the dominant choice for high-voltage WBG applications.
However, opportunities are emerging and IDTechEx predicts that OBCs and converters will be the first market entry point, with timelines given in the report. This is because OBCs and converters operate at much lower powers and the efficiency advantage of WBG materials is a clear driver for faster AC charging or internal charging of the low-voltage battery (via the converter).
Furthermore, there has been exciting progress for high voltage GaN in 2022 with new partnerships forming. VisIC Technologies, based out of Israel, is one to watch. The company develops automotive GaN power devices and partnered with Hofer Powertrain, which will use its 650V GaN chip in an 800V EV inverter design. This is one of the first examples of GaN technology being applied to a high-voltage inverter and represents a promising start. Given automotive adoption cycles are typically around four years, the door is opening for high voltage GaN adoption in EV markets, delivering a huge new growth opportunity for the industry.
This research forms part of the broader electric vehicle and energy storage portfolio from IDTechEx, who track electric vehicle markets and technologies across land, sea and air, helping you navigate whatever may be ahead. Find out more at www.IDTechEx.com/Research/EV.
Upcoming Free-to-Attend Webinar
Wide Bandgap Power Electronics: The New EV Battery
Luke Gear, Principal Technology Analyst at IDTechEx and author of this article, will be presenting a webinar on the topic on Thursday 30 March 2023 - "Wide Bandgap Power Electronics: The New EV Battery".
The new IDTechEx report "Power Electronics for Electric Vehicles 2023-2033" shows demand for electric vehicle (EV) power electronics will increase dramatically in the next ten years. This will primarily be driven by rapid growth in the BEV car market where IDTechEx predicts a 15% CAGR globally over the next decade. Currently, the weighted-average battery capacity of BEV cars is increasing in all regions, piling pressure on battery supply chains, and creating uncertainty. The result is that drive cycle efficiency must come to the forefront of powertrain design, meaning the time has come for high voltage wide bandgap (WBG) power electronics.
Improving drive cycle efficiency means that less precious energy stored in the battery is wasted when accelerating the vehicle, leading to less battery or improved range. New wide bandgap (WBG) switching devices, such as SiC MOSFETs and GaN HEMTs, are key avenues for this, and help drive 800V platform adoption for further efficiency gains. Si IGBTs are the incumbent today, with a transition to SiC MOSFET underway. Around the corner is GaN, a technology at a lower commercial readiness level, yet some of the first exciting announcements of high voltage GaN inverters show promise.
Based off the new IDTechEx report, this webinar will cover:
- Benchmarking of SiC versus GaN and future developments
- Materials evolution for power packages and industry pain points
- Market demand for SiC and opportunities for GaN
- A market outlook for EV power electronics broken down by voltage