Local strain and tunneling current modulate excitonic luminescence in MoS2 monolayers

Yalan Ma, Romana Alice Kalt, Andreas Stemmer
The excitonic luminescence of monolayer molybdenum disulfide (MoS 2 ) on a gold substrate is studied by scanning tunneling microscopy (STM). STM-induced light emission (STM-LE) from MoS 2 is assigned to the radiative decay of A and B excitons. The intensity ratio of A and B exciton emission is modulated by the tunneling current, since the A exciton emission intensity saturates at high tunneling currents. Moreover, the corrugated gold substrate introduces local strain to the monolayer MoS 2 ,
more » ... ulting in significant changes of electronic bandgap and valence band splitting. The modulation rate of strain on A exciton energy is estimated as À69 AE 5 meV/%. STM-LE provides a direct link between exciton energy and local strain in monolayer MoS 2 on a length scale of 10 nm.
doi:10.3929/ethz-b-000569822 fatcat:iyxempzaubhjpluxhspam6nlmu