Two-dimensional topological insulators hosting the quantum spin Hall effect have application potential in dissipationless electronics. To observe the quantum spin Hall effect at elevated temperatures, a wide band gap is indispensable to efficiently suppress bulk conduction. Yet, most candidate materials exhibit narrow or even negative band gaps. Here, via elegant control of van der Waals epitaxy, we have successfully grown monolayer ZrTe₅ on a bilayer graphene/SiC substrate. The epitaxial ZrTe₅ monolayer crystalizes in two allotrope isomers with different intralayer alignments of ZrTe₃ prisms. Our scanning tunneling microscopy/spectroscopy characterization unveils an intrinsic full band gap as large as 254 meV and one-dimensional edge states localized along the periphery of the ZrTe₅ monolayer. First-principles calculations further confirm that the large band gap originates from strong spin−orbit coupling, and the edge states are topologically nontrivial. These findings thus provide a highly desirable material platform for the exploration of the high-temperature quantum spin Hall effect.

具有量子自旋霍尔效应的二维拓扑绝缘体在无耗散电子器件中具有应用潜力。为了在高温下观察量子自旋霍尔效应，宽带隙对于有效抑制体传导是必不可少的。然而，大多数候选材料表现出窄带隙甚至负带隙。在这里，通过对范德华外延的优雅控制，我们成功地在双层石墨烯/SiC 衬底上生长了单层 ZrTe ₅ 。外延ZrTe ₅单层结晶为两种同素异形体，具有不同的ZrTe ₃棱镜层内排列。我们的扫描隧道显微镜/光谱学表征揭示了高达 254 meV 的固有全带隙和沿 ZrTe ₅单层外围局域的一维边缘态。第一原理计算进一步证实，大带隙源于强自旋轨道耦合，并且边缘态在拓扑上是不平凡的。因此，这些发现为探索高温量子自旋霍尔效应提供了非常理想的材料平台。