Exciton-exciton annihilation in MoSe${}_{2}$ monolayers

Exciton-exciton annihilation in MoSe $_{2}$ monolayers

Nardeep Kumar, Qiannan Cui, Frank Ceballos, Dawei He, Yongsheng Wang, and Hui Zhao

Phys. Rev. B 89, 125427 – Published 24 March 2014

Abstract

We investigate the excitonic dynamics in MoSe $_{2}$ monolayer and bulk samples by femtosecond transient absorption. Excitons are resonantly injected by a 750-nm and 100-fs laser pulse, and are detected by measuring a differential reflection of a probe pulse tuned in the range 790–820 nm. We observe a strong density-dependent initial decay of the exciton population in monolayers, which can be well described by the exciton-exciton annihilation. Such a feature is not observed in a bulk sample under comparable conditions. We also observe the saturated absorption induced by excitons in both monolayers and the bulk in the differential reflection measurements, which indicates their potential applications as saturable absorbers.

Received 4 October 2013
Revised 18 February 2014

DOI:https://doi.org/10.1103/PhysRevB.89.125427

Authors & Affiliations

Nardeep Kumar¹, Qiannan Cui¹, Frank Ceballos¹, Dawei He², Yongsheng Wang^2,*, and Hui Zhao^1,†

¹Department of Physics and Astronomy, The University of Kansas, Lawrence, Kansas 66045, USA
²Key Laboratory of Luminescence and Optical Information, Ministry of Education, Institute of Optoelectronic Technology, Beijing Jiaotong University, Beijing 100044, China

^*yshwang@bjtu.edu.cn
^†huizhao@ku.edu

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Vol. 89, Iss. 12 — 15 March 2014

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covering condensed matter and materials physics