Alex Lidow co-invented the silicon power MOSFET 40 years ago at International Rectifier. But as CEO of Efficient Power Conversion his quest is to replace silicon with gallium nitride. With the latest Gen5 series he has taken a big leap. We talked to him about that and how he got involved into GaN.
DESIGN&ELEKTRONIK: Alex, when did you first realize the potential of gallium nitride?
Alex Lidow: In the year 2000 I learned about a group of scientists in Japan who had figured out how to grow a thin layer of gallium nitride grown on top of a standard silicon wafer. That immediately turned on a light bulb with me. I already knew about compound semiconductor from my graduate work in the mid 1970’s, put there was always a cost problem with the compound semiconductor crystals. This new epitaxial development solved that problem.
Your PhD thesis was on gallium arsenide, wasn’t it?
That’s correct. The issue with wide-bandgap semiconductors is the energy of formation of the crystal. If you want to grow such a crystal you have to put a lot of energy into it because of that wide bandgap. And this makes it fundamentally expensive. So when people say silicon carbide will someday be as cheap as silicon they are fundamentally wrong, because the energy of formation of the silicon carbide crystal – and therefore the wafer cost – will always be much higher as that of a silicon crystal.
Gallium nitride has this very same issue, if you are talking about GaN as bulk wafer material. The difference comes into play, if you were able to grow it on top of a standard silicon wafer, because that adds almost no cost. That was the moment when I recognized how to make cheaper products.
Correct. These Caltech students started a company called GaNRose which I bought for IR. Later one of the co-founders of GaNRose, Bob Beach, became one of the co-founders of EPC.
But in 2007 everything changed for you as you had to step down as CEO of International Rectifier. But you said to Forbes that you were fired by the Board of Directors. Why that?
Yes, I was kicked out. Some members of the Board thought that they could do a better job running the company than my father and I could, so they put us out.
But forced to leave IR turned out to be the chance to focus on what you love to do, wasn’t it?
Usually we don’t see it this way at that time, but it allowed me to do what I love best: develop new products. As CEO of International Rectifier I was responsible for 8,000 employees and viewed myself as an administrator of problems. (Laughs)
But I had one basic issue. Since I had graduated with a PhD in 1977 exactly 30 years had passed. I’ve always stayed in technology since then, but not that deeply. Therefore I spent the first year at EPC almost every day and night reading all my old textbooks, bringing me back into solid state physics, so that I could really be a technical contributor.