Researchers at HRL Laboratories, LLC. have achieved the first demonstration of gallium nitride (GaN) complementary metal-oxide-semiconductor (CMOS) field-effect-transistor (FET) technology, and in doing so have established that the semiconductor’s superior transistor performance can be harnessed in an integrated circuit. This breakthrough may pave the way for GaN to become the technology of choice for power conversion circuits that are made in silicon today.
According to HRL Senior Staff Research Engineer and Principal Investigator Dr. Rongming Chu, GaN transistors have long excelled in both power switching and microwave/millimeter wave applications, but their potential for integrated power conversion has been unrealized. “Unless the fast-switching GaN power transistor is intentionally slowed down in power circuits, chip-to-chip parasitic inductance causes voltage instabilities,” he said.
Chu and his colleagues in HRL's Microelectronics Laboratory have overcome that limitation, developing a GaN CMOS technology that integrates enhancement-mode GaN NMOS and PMOS on the same wafer. “Integration of power switches and their driving circuitry on the same chip is the ultimate approach to minimizing the parasitic inductance,” Chu said.
Today, GaN transistors are being designed into radar systems, cellular base stations, and power converters like those found in computer notebook power adaptors. “In the near term, GaN CMOS IC applications could include power integrated circuits that manage electricity more efficiently while having a significantly smaller form factor and lower cost, and integrated circuits that can operate in harsh environments,” he said. “In the long term, GaN CMOS has the potential to replace silicon CMOS in a wide range of products.”
Chu concluded, “GaN CMOS IC was considered difficult or impossible, due to the challenge in making P-channel transistor and integrating an N-channel transistor. Our recent work opened up the possibility of making GaN CMOS IC's.”