Compared to conventional silicon-based ICs, GaN devices offer notable advantages, particularly for the development of power electronics, radio-frequency power amplifiers, and devices designed to operate in harsh environments. However, say the researchers, developing GaN complementary metal–oxide–semiconductor (CMOS) logic circuits has proved to be highly challenging, due to the intrinsically low mobility of "holes" in the material and the lack of a suitable strategy for integrating n-channel and p-channel field-effect transistors (n-FETs and p-FETs) on a single substrate.
"Our work on GaN complementary logic integrated circuits was carried out on a GaN-on-Si power HEMT (high-electron-mobility transistor) platform that currently dominates the mainstream commercial GaN power electronics device technology," says Prof. Kevin J. Chen, who led the study. "This is a planar technology that is particularly suitable for the high-density integration of multi-functional blocks."
To be efficient and complete, a power conversion system requires both core power switching devices - such as power transistors and rectifiers - and peripheral circuits that enable their driving, sensing, protective, and control functionalities. Therefore, say the researchers, to unlock the full potential of GaN power HEMTs, enabling their high-frequency operation and the realization of smaller, more compact power systems, it would be preferable for power switching devices and peripheral circuits to be seamlessly integrated on a single chip.
"Current GaN HEMTs are all n-FETs with electrons as the carriers, thus all the peripheral circuits are also based on n-FETs," says Dr. Zheyang Zheng, one of the researchers who carried out the study. "However, logic gates (which are a major constituent in the peripheral circuits) solely based on n-FETs, are much less energy-efficient than the well-known CMOS (complementary MOS) logic architecture that features complementary n-FETs and p-FETs."
The main objective of the recent study, say the researchers, was to develop GaN complementary or CMOS-like logic ICs that are compatible with existing GaN power HEMT platforms. Due to their advantages and wide bandgap, these ICs could benefit a