Zhang Chendong, Li Ming-Yang, Tersoff Jerry, Han Yimo, Su Yushan, Li Lain-Jong, Muller David A, Shih Chih-Kang
Department of Physics, University of Texas at Austin, Austin, TX, USA.
School of Physics and Technology, Wuhan University, Wuhan, China.
Nat Nanotechnol. 2018 Feb;13(2):152-158. doi: 10.1038/s41565-017-0022-x. Epub 2018 Jan 15.
Monolayer transition metal dichalcogenide heterojunctions, including vertical and lateral p-n junctions, have attracted considerable attention due to their potential applications in electronics and optoelectronics. Lattice-misfit strain in atomically abrupt lateral heterojunctions, such as WSe-MoS, offers a new band-engineering strategy for tailoring their electronic properties. However, this approach requires an understanding of the strain distribution and its effect on band alignment. Here, we study a WSe-MoS lateral heterojunction using scanning tunnelling microscopy and image its moiré pattern to map the full two-dimensional strain tensor with high spatial resolution. Using scanning tunnelling spectroscopy, we measure both the strain and the band alignment of the WSe-MoS lateral heterojunction. We find that the misfit strain induces type II to type I band alignment transformation. Scanning transmission electron microscopy reveals the dislocations at the interface that partially relieve the strain. Finally, we observe a distinctive electronic structure at the interface due to hetero-bonding.
包括垂直和横向 p-n 结在内的单层过渡金属二硫属化物异质结，因其在电子学和光电子学中的潜在应用而备受关注。原子级突变横向异质结（如 WSe-MoS）中的晶格失配应变，为调整其电子特性提供了一种新的能带工程策略。然而，这种方法需要了解应变分布及其对能带排列的影响。在此，我们使用扫描隧道显微镜研究了 WSe-MoS 横向异质结，并对其莫尔条纹图案进行成像，以高空间分辨率绘制完整的二维应变张量。使用扫描隧道谱，我们测量了 WSe-MoS 横向异质结的应变和能带排列。我们发现失配应变会导致 II 型到 I 型能带排列转变。扫描透射电子显微镜揭示了界面处的位错，这些位错部分缓解了应变。最后，由于异质键合，我们在界面处观察到了独特的电子结构。
