Investigation of the Photoluminescence Spectra of MoSe2 Monolayer-Based Structures as a Function of Electric Field and Temperature

Photoluminescence spectra of MoSe2 monolayers encapsulated with hexagonal boron nitride are studied over the 5–107 K temperature range under controlling the density of charge carriers in a monolayer. The change in the density was performed by applying a potential difference between the external contact and the contact connected to the monolayer. The pattern of the emission lines of an exciton and trion as a function of the applied voltage is studied. It has been found that energy splitting Δ E_X-T between the photoluminescence lines of excitons and trions monotonically increases with temperature from 25 to 31 meV and depends on a gate voltage. Integral intensity ratio I_T/I_X exhibits threshold-like pattern versus voltage consistent with an increase in the electron density in the monolayer. The estimated resident electron density Δn ≃ 1.4 × 1012 cm–2 has been obtained at T = 5 K.