Unraveling the Defect Emission and Exciton-Lattice Interaction in Bilayer WS2
Author(s): Tan, QH (Tan, Qing-Hai); Ren, SL (Ren, Shu-Liang); Shen, T (Shen, Tao); Liu, XL (Liu, Xue-Lu); Shi, W (Shi, Wei); Sun, YJ (Sun, Yu-Jia); Deng, HX (Deng, Hui-Xiong); Tan, PH (Tan, Ping-Heng); Zhang, J (Zhang, Jun)
Source: JOURNAL OF PHYSICAL CHEMISTRY C Volume: 123 Issue: 7 Pages: 4433-4440 DOI: 10.1021/acs.jpcc.8b11011 Published: FEB 21 2019
Abstract: Defect states and exciton of two-dimensional semiconductors play an important role in fundamental research and device applications. Here, we reported the defect emissions and exciton-lattice interaction of bilayer WS2. These defect emissions show a very narrow linewidth, doublet peaks, spatial localization, saturation with pumping power and can survive up to 180 K. The behavior of these defect emissions means it should be a good candidate as a single photon source. Besides defect emissions, direct exciton and two indirect excitons due to band-to-band transition are identified. By analyzing the temperature-dependent photoluminescence (PL) spectra of excitons, we obtained the Debye temperature, exciton-phonon coupling constant, and pressure coefficient terms of all excitons. Combining the PL experiments and density functional theory calculations, we attributed two indirect excitons to the Lambda-K and Lambda-Gamma transitions, respectively. Our study not only gives a better understanding of the defect emissions and energy band structure in multilayer materials, but also provides an opportunity for defect and band engineering in two-dimensional layered systems.
全文链接:https://pubs.acs.org/doi/abs/10.1021%2Facs.jpcc.8b11011