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Atomic Mechanism of Strain Alleviation and Dislocation Reduction in Highly Mismatched Remote Heteroepitaxy Using a Graphene Interlayer

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journal contribution
posted on 11.04.2022, 15:11 authored by Bingyao Liu, Qi Chen, Zhaolong Chen, Shenyuan Yang, Jingyuan Shan, Zhetong Liu, Yue Yin, Fang Ren, Shuo Zhang, Rong Wang, Mei Wu, Rui Hou, Tongbo Wei, Junxi Wang, Jingyu Sun, Jinmin Li, Zhongfan Liu, Zhiqiang Liu, Peng Gao
Remote heteroepitaxy is known to yield semiconductor films with better quality. However, the atomic mechanisms in systems with large mismatches are still unclear. Herein, low-strain single-crystalline nitride films are achieved on highly mismatched (∼16.3%) sapphire via graphene-assisted remote heteroepitaxy. Because of a weaker interface potential, the in-plane compressive strain at the interface releases by 30%, and dislocations are prevented. Meanwhile, the lattice distortions in the epilayer disappear when the structure climbs over the atomic steps on substrates because graphene renders the steps smooth. In this way, the density of edge dislocations in as-grown nitride films reduces to the same level as that of the screw dislocations, which is rarely observed in heteroepitaxy. Further, the indium composition in InxGa1–xN/GaN multiquantum wells increases to ∼32%, enabling the fabrication of a yellow light-emitting diode. This study demonstrates the advantages of remote heteroepitaxy for bandgap tuning and opens opportunities for photoelectronic and electronic applications.