Stark Effect in a Heterostructure Based on a MoSe₂ Monolayer

The effect of a vertical electric field on the photoluminescence of a MoSe₂ monolayer encapsulated with hexagonal boron nitride was investigated. The spectra showed a quadratic (in applied potential difference) shift of the photoluminescence lines of excitons and trions, as well as changes in their intensity. It was found that the magnitude of the Stark shift significantly exceeds the theoretically predicted one. It was determined that the energy distance between the trion and exciton lines in the spectra varies with the external field, which is due to the dependence of the density of free charge carriers in the monolayer on the field. This effect made it possible to determine the density of free charge carriers in the monolayer, which varies with the field and lies in the range (0.3–3.15) × 10¹² cm^–2.