Experimental determination of giant polarization in wurtzite III-nitride semiconductors
Haotian Ye, Ping Wang, Rui Wang, Jinlin Wang, Xifan Xu, Ran Feng, Tao Wang, Wen‐Yi Tong, Fang Liu, Bowen Sheng, Wenjie Ma, Bo An, Hongjian Li, Zhaoying Chen, Chun‐Gang Duan, Weikun Ge, Bo Shen, Xinqiang Wang
Abstract
Polarization engineering has revolutionized the photonic and electronic landscape of III-nitride semiconductors over the past decades. However, recent revelations of giant ferroelectric polarization in wurtzite III-nitrides challenge the long-standing paradigms. Here, we experimentally elucidate the polarization, including its magnitude and orientation, and its relationship to lattice polarity in III-nitrides. Those experimentally determined polarizations exceeding 1 C/m2 with an upward orientation in metal-polar wurtzite nitride compounds align with recent theoretical predictions. To reconcile these findings, a unified polarization framework is established based on the centrosymmetric layered-hexagonal reference structure. This unified framework redefines the polarization landscape in contemporary GaN heterostructures, quantum structures, and ferroelectric heterostructures. Furthermore, we predict significant tunability and a dramatic increase in sheet carrier concentration in ferroelectric ScAlN/GaN heterostructures, heralding advancements in high-power, high-frequency, and reconfigurable transistors, and non-volatile memories. This work bridges the critical gap in the understanding of polarization in both conventional and ferroelectric wurtzite nitrides, offering fundamental insights and paving the way for next-generation photonic, electronic, and acoustic devices. The authors provide experimental evidence for giant polarization in wurtzite III-nitrides, establishing a unified framework for understanding and engineering polarization in these materials and their functional device architectures.