Wu Yuanpeng, Zhou Peng, Xiao Yixin, Sun Kai, Wang Ding, Wang Ping, Mi Zetian
Department of Electrical Engineering and Computer Science, University of Michigan, Ann Arbor, MI 48109.
Department of Materials Science and Engineering, University of Michigan, Ann Arbor, MI 48109.
Proc Natl Acad Sci U S A. 2023 Oct 31;120(44):e2303473120. doi: 10.1073/pnas.2303473120. Epub 2023 Oct 24.
Interface engineering in heterostructures at the atomic scale has been a central research focus of nanoscale and quantum material science. Despite its paramount importance, the achievement of atomically ordered heterointerfaces has been severely limited by the strong diffusive feature of interfacial atoms in heterostructures. In this work, we first report a strong dependence of interfacial diffusion on the surface polarity. Near-perfect quantum interfaces can be readily synthesized on the semipolar plane instead of the conventional -plane of GaN/AlN heterostructures. The chemical bonding configurations on the semipolar plane can significantly suppress the cation substitution process as evidenced by first-principles calculations, which leads to an atomically sharp interface. Moreover, the surface polarity of GaN/AlN can be readily controlled by varying the strain relaxation process in core-shell nanostructures. The obtained extremely confined, interdiffusion-free ultrathin GaN quantum wells exhibit a high internal quantum efficiency of ~75%. Deep ultraviolet light-emitting diodes are fabricated utilizing a scalable and robust method and the electroluminescence emission is nearly free of the quantum-confined Stark effect, which is significant for ultrastable device operation. The presented work shows a vital path for achieving atomically ordered quantum heterostructures for III-nitrides as well as other polar materials such as III-arsenides, perovskites, etc.
原子尺度异质结构中的界面工程一直是纳米尺度和量子材料科学的核心研究重点。尽管其至关重要，但异质结构中界面原子的强扩散特性严重限制了原子有序异质界面的实现。在这项工作中，我们首次报道了界面扩散对表面极性的强烈依赖性。在GaN/AlN异质结构的半极性平面而非传统的 -平面上，可以很容易地合成近乎完美的量子界面。第一性原理计算表明，半极性平面上的化学键构型可以显著抑制阳离子替代过程，从而形成原子级尖锐的界面。此外，通过改变核壳纳米结构中的应变弛豫过程，可以很容易地控制GaN/AlN的表面极性。所获得的极其受限、无相互扩散的超薄GaN量子阱表现出约75%的高内量子效率。利用一种可扩展且稳健的方法制造了深紫外发光二极管，其电致发光发射几乎没有量子限制斯塔克效应，这对于超稳定器件运行至关重要。所展示的工作为实现III族氮化物以及其他极性材料（如III族砷化物、钙钛矿等）的原子有序量子异质结构提供了一条重要途径。
