Abstract
We present an analytical investigation of the optical absorption spectrum of monolayer molybdenum-disulfide. Based on the density matrix formalism, our approach gives insights into the microscopic origin of excitonic transitions, their relative oscillator strength, and binding energy. We show analytical expressions for the carrier-light coupling element, which contains the optical selection rules and describes well the valley-selective polarization in . In agreement with experimental results, we find the formation of strongly bound electron-hole pairs due to the efficient Coulomb interaction. The absorption spectrum of MoS features two pronounced peaks corresponding to the A and B exciton. For MoS on a SiO substrate, these are characterized by binding energies of 455 meV and 465 meV, respectively. Our calculations reveal their relative oscillator strength and predict the appearance of further low-intensity excitonic transitions at higher energies. The presented approach is applicable to other transition metal dichalcogenides and can be extended to investigations of trion and biexcitonic effects.
- Received 1 November 2013
- Revised 13 February 2014
DOI:https://doi.org/10.1103/PhysRevB.89.125309
©2014 American Physical Society