Zhang Zhenyu, Wang Tao, Jiang Hailing, Xu Xifan, Wang Jinlin, Wang Ziruo, Liu Fang, Yu Ye, Zhang Yuantao, Wang Ping, Gao Peng, Shen Bo, Wang Xinqiang
State Key Laboratory for Mesoscopic Physics and Frontiers Science Center for Nano-optoelectronics, School of Physics, Peking University, Beijing, China.
Electron Microscopy Laboratory, School of Physics, Peking University, Beijing, China.
Nat Commun. 2024 Nov 30;15(1):10436. doi: 10.1038/s41467-024-54921-8.
Group-III nitride semiconductors such as GaN have various important applications based on their three-dimensional form. Previous work has demonstrated the realization of buckled two-dimensional GaN, which can be used in GaN-based nanodevices. However, the understanding of buckled two-dimensional GaN remains limited due to the difficulties in experimental characterization. Here, for the first time, we have experimentally determined the phonon dispersion of buckled two-dimensional GaN by using monochromatic electron energy loss spectroscopy in conjunction with scanning transmission electron microscopy. A phonon band gap of ~40 meV between the acoustic and optical phonon branches is identified for buckled two-dimensional GaN. This phonon band gap is significantly larger than that of ~20 meV for the tetrahedral-coordinated three-dimensional GaN. Our theoretical calculations confirm this larger phonon band gap. Our findings provide critical insights into the phonon behavior of buckled two-dimensional GaN, which can be used to guide high-performance thermal management in GaN-based high-power devices.
诸如氮化镓（GaN）之类的III族氮化物半导体基于其三维形态具有各种重要应用。先前的工作已经证明了实现了可用于基于GaN的纳米器件的弯曲二维GaN。然而，由于实验表征的困难，对弯曲二维GaN的理解仍然有限。在这里，我们首次通过结合单色电子能量损失谱和扫描透射电子显微镜，实验测定了弯曲二维GaN的声子色散。对于弯曲二维GaN，在声学和光学声子分支之间确定了约40 meV的声子带隙。该声子带隙明显大于四面体配位的三维GaN的约20 meV。我们的理论计算证实了这个更大的声子带隙。我们的发现为弯曲二维GaN的声子行为提供了关键见解，可用于指导基于GaN的高功率器件中的高性能热管理。
