Engineering the exciton spontaneous emission time in MoSe₂ monolayer

Encapsulation of monolayers such as MoSe₂ in hexagonal boron nitride (hBN) yields narrow optical transitions approaching the homogenous exciton linewidth. In time-resolved photoluminescence measurements we demonstrate that the exciton radiative lifetime in the MoSe₂ monolayer can be tuned by a factor 10 (typically from 1 to 10 ps) as a function of the hBN thickness. This variation is a consequence of the Purcell effect and it is in very good agreement with the calculated dependence using transfer matrix techniques [1]. We show that the exciton linewidth measured in cw photoluminescence can be controlled as well. The variation of the charged exciton lifetime due to cavity-like effects will also be discussed.
[1] H.H. Fang, B. Han et al, Phys. Rev. Lett 123, 067401 (2019)