| AVS 64th International Symposium & Exhibition | |
| 2D Materials Focus Topic | Tuesday Sessions |
| Session 2D+AS+SA+SP-TuM |
| Session: | 2D Materials Characterization including Microscopy and Spectroscopy |
| Presenter: | Fan Zhang, Virginia Polytechnic Institute and State University |
| Authors: | F. Zhang, Virginia Polytechnic Institute and State University Z. Lu, Tsinghua University, PR China H. Zheng, Virginia Polytechnic Institute and State University K. Park, Virginia Polytechnic Institute and State University L. Jiao, Tsinghua University, PR China C. Tao, Virginia Polytechnic Institute and State University |
| Correspondent: | Click to Email |
2D materials like atomically thin transition metal dichalcogenides (TMDs) have received tremendous attentions for their unique properties and high potential applications. Recent developments on synthesis of 2D heterosrtuctures through the chemical vapor deposition (CVD) method provide an unprecedented opportunity to create and tune the intriguing electronic and optical properties of 2D materials such as engineering the band gaps. These 2D heterostructrues have a wide range of applications in electronics and optics, for example, tunneling transistors, single-photon emission devices and photovoltaic devices. To further optimize and design 2D heterostructures, it is essential to investigate the structural and electronic properties at the atomic scale, which is however still lacking.
In this presentation, we will focus on a high-quality MoS2/WS2 heterostructure grown on SiO2 using the CVD method. Scanning tunneling microscopy (STM) and spectroscopy (STS) were performed to study the morphology and band structures of both MoS2 monolayer and MoS2/WS2 heterobilayer. Atomically resolved STM images were obtained on the monolayer, heterobilayer and the interface between the monolayer and heterobilayer. The height histograms acquired respectively on the monolayer and the heterobilayer indicate that the heterobilayer is higher than the monolayer with a height difference of 0.85 ± 0.10 nm. The roughness of the monolayer and heterobilayer was for the first time quantified by STM. The root mean square (RMS) roughness of the heterobilayer is 0.253 ± 0.020 nm compared with 0.362 ± 0.031 nm of the monolayer. We also performed STS measurements on the system. Our STS results and density functional theory (DFT) calculations reveal the band gaps of the heterobilayer and the MoS2 monolayer, which are similar to the previously reported results on MoS2/WS2 heterostructures fabricated through the mechanical exfoliation method.