Spatial-Resolved Crystalline Characteristics in Few-Layered Molybdenum Disulfide Measured by Focused X-Ray Laue Diffraction
Ling Lee1*, Jyun-Hong Chen1, Hsin-Yi Tang1, Teng-Yu Su1, Yu-Lun Chueh1, Ching-Shun Ku2
1Department of Materials Science and Enineering, National Tsing Hua University, Hsinchu, Taiwan
2National Synchrotron Radiation Research Center, Hsinchu, Taiwan
* Presenter:Ling Lee,
In order to increase the optoelectronics feasibilities, the large-area fabrication of high-quality transition metal dichalcogenide is essential. For this purpose, vapor phase synthesized techniques, including chemical vapor deposition (CVD) and post chemical vapor reaction (CVR), attracts increasing interests. However, grain boundaries and crystalline imperfections still hinders the performance in terms of suppressed carrier transportation as well as the luminescence efficiency. This challenges not only the syntheses, but also the characterization techniques with spatial resolution within the submicron scale.
In this work, we accomplished the Laue diffraction characterizations of the bilayered MoS2 by the focused polychromatic x-ray beam provided in Taiwan Photon Source (TPS) of National Synchrotron Radiation Research Center (NSRRC). First, the single crystalline bilayer MoS2 synthesized on c-plane sapphire substrate was successfully demonstrated. Based on the intensity variations and the shift in spot positions, the spatial distributions of thickness, orientation in the basal plane, and deviatoric strain in the MoS2 layer were provided.
Second, we succeed in preparing large-area bilayer MoS2 on inclined facets of patterned sapphire substrate as well as the spatial-resolved Laue diffraction. The dialtational and deviatoric strain components in MoS2 on different facets are revealed by micro-photoluminescence and spatial-resolved Laue diffraction, respectively. It provided effective information to indicate that the growth of MoS2 is not completely via the Van der Waals epitaxy, and strain could be modified by the different thermal expansion coefficient at each facets.

Keywords: molybdenum disulfide, Laue diffraction, focused x-ray