Taking GaN CMOS To The IC
Forming logic circuits with a power HEMT platform that features a p-GaN gate provides a significant step towards unlocking the full potential of GaN integration
BY ZHEYANG ZHENG, LI ZHANG AND KEVIN CHEN FROM THE HONG KONG UNIVERSITY OF SCIENCE AND TECHNOLOGY
CMOS TECHNOLOGY continues to prevail in very large-scale and mixed-signal ICs. In these forms of circuit, CMOS has dominated for the past four decades, thanks to topping the list of the most energy-efficient circuit topologies. Whenever new electronic devices are explored in other semiconductor materials, there is a hunt for complementary devices, to see whether this could lead to a superior successor to silicon CMOS. However, such a pursuit tends to be full of obstacles, with GaN providing a typical example.
This wide-bandgap semiconductor, blessed with an inherent capability to form a very high-mobility two-dimensional electron gas (2DEG) channel, has many attractive attributes. This has driven widespread deployment of n-channel GaN HEMTs in 5G base stations, as well as ultra-compact power adaptors and supplies for mobile devices. In the near-term, more exciting applications are sure to emerge that are power-hungry, yet demand ultra-compactness in power supplies. This will create an appreciable market for GaN. However, much is still to be done when it comes to GaN CMOS. Efforts have been held back by undesirable material properties for implementing p-channel FETs and a lack of essential applications that would spur development.