2016/12/13 by J. Jadczak, Jadczak, J., Joanna Kutrowska-Girzycka +15 · 1 citation
Materials Science · #2D Materials and Applications #FOS: Physical sciences #Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
paper · pdf · doi:10.48550/arxiv.1612.04122
openalex publication_date 2016/12/13 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
Atomically thin semiconducting transition-metal dichalcogenides provide novel insights into the physics of many-body effects mediated by Coulomb interactions. Here, we report on temperature-dependent (T = 7-295 K) reflectance contrast and photoluminescence studies of three-particle complexes in n-doped WS2 monolayers. In low-temperature reflectance contrast spectra we observe distinct resonances of the neutral exciton, negative trion and exciton bound to a donor (X, X- and XD). For temperatures above 80 K, reflectance contrast signatures of the XD disappear, whereas the X- remains detectable up to 240 K, despite the fact that the XD signal is more red-shifted from the neutral exciton than that of the X-. This experimental observation underlines that in WS2 the dissociation energy of X- considerably exceeds (factor of 2.5) that of XD. In the laser-power dependent photoluminescence experiments, performed at room temperature, we demonstrate the control of the intensity ratio and energy position of the X and X- lines, which allows us to evaluate the trion binding energy. Moreover, we demonstrate that the room-temperature PL is sensitive to the environmental gas (ambient, N2, He).