Xinxin Li1,2,Wei Wang2,Xuedan Ma2,1
The University of Chicago1,Argonne National Laboratory2
Xinxin Li1,2,Wei Wang2,Xuedan Ma2,1
The University of Chicago1,Argonne National Laboratory2
Atomically thin transition metal dichalcogenides (TMDs), including WS2, WSe2, MoS2, MoSe2, have attracted considerable interest due to their promising applications in electronic and optoelectronic devices.[i],[ii],[iii] Defects in TMD monolayers (MLs) can serve as excitonic traps, leading to exciton localization and even single photon emission.[iv],[v],[vi] In this study, we systematically investigate the influence of strain profiles on the emission properties of WSe2 MLs by suspending them onto trenches with various widths. A red shift in the photoluminescence spectra can be observed as the trench width increases, indicating strain-induced bandgap narrowing in the WSe2 MLs. Abundance of defects were created in the MLs at specific regions suspended above the trenches, consistent with the local strain profiles obtained from numerical simulations. Noteworthy, photon antibunching, a hallmark of single photon emission, was only observed for defects created under certain strain amplitudes. A further increase in the strain amplitude reduces the exciton localization degree. These findings would help elucidate future design of quantum defects in TMDs for quantum optics applications. <br/><br/><br/>[i]. Mak, K., Shan, J. Photonics and optoelectronics of 2D semiconductor transition metal dichalcogenides. Nature Photon. 10, 216–226 (2016)<br/><br/>[ii]. Lee, J., Mak, K. & Shan, J. Electrical control of the valley Hall effect in bilayer MoS2 transistors. Nature Nanotech 11, 421–425 (2016)<br/><br/>[iii]. Zeng, H., Dai, J., Yao, W., Xiao, X., Cui, X., Valley polarization in MoS2 monolayers by optical pumping. Nature Nanotech 7, 490–493 (2012). <br/><br/>[iv]. Palacios-Berraquero, C., Kara, D. M., Montblanch, A. R.P., Barbone, M., Latawiec, P., Yoon, D., Ott, A. K., Loncar, M., Ferrari, A. C., Atatüre, M., Large-scale quantum-emitter arrays in atomically thin semiconductors. Nat Commun 8, 15093 (2017).<br/><br/>[v]. Yu, L., Deng, M., Zhang, J. L., Borghardt, S., Kardynal, B., Vučković, J., and Heinz, T. F., Site-Controlled Quantum Emitters in Monolayer MoSe2, Nano Lett. 21, 6, 2376–2381 (2021)<br/><br/>[vi]. Peng, L., Chan, H., Choo, P., Odom, T. W., Sankaranarayanan, S. K. R. S., Ma, X., Creation of Single-Photon Emitters in WSe2 Monolayers Using Nanometer-Sized Gold Tips, Nano Lett. 20, 8, 5866–5872 (2020)