May 2020

OPINION 5 www.power-mag.com Issue 2 2020 Power Electronics Europe Ten Years ago, in the year 2010, International Rectifier (IR), now part of Infineon Technologies AG, introduced the first commercially available cascoded GaN power transistor on the market, soon after followed by Efficient Power Conversion Corp. (EPC), a spin-off of IR and co-founded by former IR-CEO Alex Lidow. EPC followed a different approach to make a non-cascoded normally-off GaN power transistor – the so-called enhancement mode. Commercially viable Si power FETs, introduced some 40 years ago, enabled the widespread adoption of switch-mode power supplies, replacing the linear regulator as the dominant power architecture, the Si power FET has become the dominant power device. The Si IGBT, combining the ease of MOS charge control with the benefits of conductivity modulated drift resistivity, has been another mainstay, especially in the lower frequency conversion systems, e.g. motor drive inverters. Of course, the same minority carrier injection that provides for lower ohmic losses also increases switching losses through the effects of subsequent tail currents. Over the last four decades significant engineering efforts have driven the improvement in the performance figure of merit (FOM) of these devices by more than an order of magnitude. However, as this technology approaches maturity, it becomes increasingly expensive to achieve even modest improvements in the device FOM. Ten years ago GaN based power devices already provided a factor of 2 to 10 in specific on-resistance improvement over state-of-the- art silicon based devices, but at a very early stage as was the case in Silicon power device development over the last 40 years. GaN based power devices are expected by market researchers to improve rapidly over the next ten years. “Like the power MOSFET of 1976, we are beginning an exciting journey with new products and breakthrough capabilities almost monthly. The power MOSFET is not dead, but is nearing the end of the road of major improvements in performance and cost. GaN will most probably become the dominant technology over the next decade due to its large advantages in both performance and cost; advantage gaps that promise to widen as we quickly climb the learning curve”, stated Alex Lidow in an article “Can Gallium Nitride Replace Silicon?” published in PEE 3/2010. Now in the year 2020 this question has been partially answered. “GaN-on-Si devices, such as the ePower Stage EPC2152, are a major step toward developing full power systems-on-a-chip. Over the next few years there will be many more such products introduced to the market, each one reducing design time while improving system efficiency and cost. The era of the discrete transistor is coming to a close”, Lidow pointed out in our cover story. Since 2010 the GaN-on-Silicon power device landscape was dominated by pure GaN start-up players like EPC, GaN Systems, Transphorm, and Navitas, which chose the foundry model and mostly used TSMC, Episil, or X-FAB. In just a few years, IR/Infineon and Transphorm have reached the strongest IP position in the patent landscape, according to market researcher Yole. Infineon has the strongest IP portfolio to front the growing of GaN power market. Transphorm is a major force in the power GaN IP arena, with a new licensee Nexperia. In a GaN power market bursting with potential, more players are expected to enter and benefit from high-volume opportunities. For example, LED manufacturers may want to leverage their GaN-on-Sapphire know-how and high production capacity to derive considerable benefit. A fierce competition is likely to break out between all of these actors and their different business models. However, everyone’s ultimate goal is to gain a foothold in the lively GaN power market, earn a design win, and ramp up. In the GaN-on-Sapphire patent landscape, Power Integrations (PI) is the best-known player. In fall 2019 they announced that it had not only shipped close to 3 million units of its new Innoswitch3 with a SiP GaN product, but also earned a design win with a major smartphone OEM. In April 2020 the number has increased to 5 million. An expansion of its Innoswitch3 CV/CC flyback switcher ICs incorporating a 750 V PowiGaN transistor making it the so far highest voltage rated GaN device on the market. Most of PI’s new products incorporate GaN due to its higher efficiency and switching frequency capability, which relates to smaller and lighter power supplies. The obvious market for such products is the cell phone charger, with its increasing demand for higher power coming from 5 G and fast charging. But also the TV market is very interested in GaN due to efficiency regulations, and thirdly the appliance market looks for elimination of heatsinks in their products. Heatsinks are due their mass a weak point when vibrations occur and thus a reliability problem. And overall efficiency is here also a prerequisite. Also GaN can withstand short-term transients much better than Silicon, which makes this technology more robust. Numerous other players have also developed IP related to GaN-on-Sapphire for power applications, including CorEnergy, Powdec and Seoul Semiconductor. Yole forecasts the GaN power business will exceed $350 million by 2024, with a compound annual growth rate (CAGR) of 85 %, making it the most attractive power semiconductor market segment. That’s why we have prepared a selection of features in this issue. Enjoy reading and stay healthy. Achim Scharf PEE Editor Ten Years Power GaN – A Success Story