Researchers at the HRL Microelectronics Laboratories in California have demonstrated complementary metal-oxide-semiconductor (CMOS) field-effect-transistor (FET) technology using gallium nitride (GaN), a development that could see GaN replace silicon in power conversion circuits.
According to HRL engineer 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 unrealised.
"Unless the fast-switching GaN power transistor is intentionally slowed down in power circuits, chip-to-chip parasitic inductance causes voltage instabilities," he said.
However, they 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 minimising 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 ICs."
The research by Chu and his team was published in IEEE Electron Device Letters. HRL Laboratories is a corporate research-and-development laboratory in Malibu, California, owned by Boeing and General Motors. It specialises in research into sensors and materials, information and systems sciences, applied electromagnetics, and microelectronics.
Photo: Dan Little Photography/HRL Laboratories