Exploring new two-dimensional (2D) van der Waals (vdW) systems is at the forefront of materials physics. Here, through molecular beam epitaxy on graphene-covered SiC(0001), we report successful growth of AlSb in the double-layer honeycomb (DLHC) structure, a 2D vdW material which has no direct analogue to its 3D bulk and is predicted kinetically stable when freestanding. The structural morphology and electronic structure of the experimental 2D AlSb are characterized with spectroscopic imaging scanning tunneling microscopy and cross-sectional imaging scanning transmission electron microscopy, which compare well to the proposed DLHC structure. The 2D AlSb exhibits a bandgap of 0.93 eV versus the predicted 1.06 eV, which is substantially smaller than the 1.6 eV of bulk. We also attempt the less-stable InSb DLHC structure; however, it grows into bulk islands instead. The successful growth of a DLHC material here opens the door for the realization of a large family of novel 2D DLHC traditional semiconductors with unique excitonic, topological, and electronic properties.
@article{arxiv.2101.07431,
title = {Realization of AlSb in the double layer honeycomb structure: a robust new class of two-dimensional material},
author = {Le Qin and Zhi-Hao Zhang and Zeyu Jiang and Kai Fan and Wen-Hao Zhang and Qiao-Yin Tang and Hui-Nan Xia and Fanqi Meng and Qinghua Zhang and Lin Gu and Damien West and Shengbai Zhang and Ying-Shuang Fu},
journal= {arXiv preprint arXiv:2101.07431},
year = {2021}
}