The Freescale GaAs MOSFET exhibits carrier mobility in the conducting channel that is 30 times higher than that of silicon MOSFETs, even those using a next-generation gate insulator, hafnium dioxide.

Freescale's Ga₂O₃/GdGaO dielectric stack has electrical characteristics similar to those of hafnium dioxide, and that got the attention of Jack Lee, a professor in the department of electrical and computer engineering at the University of Texas at Austin. "Right now we're working on hafnium dioxide simply because of our experience," says Lee, who leads a team working on III-V MOSFETs. "But I think the oxide that [Passlack's] working on is something that we definitely want to look at, too."

Lee's not alone. The Semiconductor Research Corp., based in Research Triangle Park, N.C., is launching a new research program aimed in part at finding ways to fabricate III-V MOSFETs using CMOS technology. Then there's Intel. Wilman Tsai, who is involved in III-V research at Intel, would say of Freescale's innovation only that some of the content in this article "is very sensitive to what Intel is doing, so we are not in a position to make public comment."

So far, only discrete devices (just transistors, as opposed to transistors incorporated into circuits) have emerged from Passlack's team. But if Freescale can integrate GaAs MOSFETs into circuits—by all accounts a difficult but not insurmountable task—several intriguing possibilities open up.

"One of the applications could be as a replacement for the silicon LDMOS [laterally diffused MOS] microwave power transistors that are used in power amplifiers for base stations," says Stan Bruederle, research vice president of Gartner Semiconductor Research, San Jose, Calif.

Ultra-low-power handsets that you charge once a month could also be in the offing, according to Karl Johnson, director of Freescale's microwave and mixed signal technology laboratory in Tempe, Ariz. In fact, GaAs MOSFETs could completely revolutionize handset design by integrating power amplifiers, transmit/receive switches, and power controls on one chip.

Furthermore, a cellphone's typically sluggish multimedia experience might be amped up considerably using GaAs integrated circuits. As Johnson explains, if you could directly convert the analog signal as it comes into the antenna at a higher frequency into a digital signal, you would eliminate a lot of the components that sit between the base band and the RF section of the phone.

As analysts and Freescalers alike caution, there's a long way to go before GaAs MOSFETs make it to market. Even so, Passlack has given Freescale a huge head start on something a lot of other chip makers now want to develop themselves.