Due to its unique layer-number dependent electronic band structure and strong excitonic features, atomically thin MoS2 is an ideal 2D system where intriguing photoexcited-carrier-induced phenomena can be detected in excitonic luminescence. We perform micro-photoluminescence (PL) measurements and observe that the PL peak redshifts nonlinearly in mono- and bi-layer MoS2 as the excitation power is increased. The excited carrier-induced optical bandgap shrinkage is found to be proportional to n4/3, where n is the optically-induced free carrier density. The large exponent value of 4/3 is explicitly distinguished from a typical value of 1/3 in various semiconductor quantum well systems. The peculiar n4/3 dependent optical bandgap redshift may be due to the interplay between bandgap renormalization and reduced exciton binding energy.
CITATION STYLE
Park, Y., Han, S. W., Chan, C. C. S., Reid, B. P. L., Taylor, R. A., Kim, N., … Kim, K. S. (2017). Interplay between many body effects and Coulomb screening in the optical bandgap of atomically thin MoS2. Nanoscale, 9(30), 10647–10652. https://doi.org/10.1039/c7nr01834g
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