Tunable and Enhanced Photoluminescence with Valley Polarization in MoS2/Pt nanocomposites

Asha Yadav^1*, Yu-Chen Chang¹, Yann-Wen Lan¹, Ting-Hua Lu¹

¹Physics, National Taiwan Normal University, Taipei, 10610, Taiwan

* Presenter:Asha Yadav, email:ashayadav@gapps.ntnu.edu.tw

Miniaturization and quantum technology, high speed computing, highly sensitive detection and transmission system is the need of next generation optoelectronic devices which is reliant on electron spin states or photon entanglement states which depends on the degree of circular (DoCP) polarization in Photoluminescence which characterise the valley degree of freedom in transition metal dichalcogenides.[1,2] In this research work, we have studied the effect of metal (Pt) thin film on the DoCP(%) of monolayer molybdenum disulphide (MoS2) using two different excitations energy with the variation in laser power at room temperature. For resonant excitation, DoCP (%) without Pt is higher than with Pt at different laser power, while with Pt it decreases with decreases in laser power. Interestingly, at non resonant excitation, without Pt, there is no change in polarizations in the luminescence spectra with decrease in laser power whereas with Pt, DoCP(%) increases from 6% to 10%, a high DoCP of 36% has been observed in MoS2/Pt nanocomposites for thicker Pt film with enhanced and tunable photoluminescence. Achieving polarization at room temperature at an excitation above the bandgap opens a new pathway in manipulating the valley population in MoS2 monolayer, possibility of development of spintronic and valleytronic based optoelectronic devices.

References
[1] Xiao, D, Liu, “Coupled spin and valley physics in monolayers of MoS2 and other group-VI dichalcogenides,” Phys. Rev. Lett. 108 (19), 196802 (2012).
[2] Wan, Y, “Epitaxial single‐layer MoS2 on GaN with enhanced valley helicity. Advanced Materials,” 30 (5), 1703888 (2018).

Keywords: MoS2/Pt nanocomposites, Valley Polarization, Chemical Vapor Deposition