Pulsed cathodoluminescence and Raman spectra of MoS2 nanocrystals at different excitation electron energy densities and laser wavelengths

Molybdenum disulfide nanocrystals exhibit direct dependencies of the Raman peaks' intensities and their positions on the thicknesses of the nanocrystals. This indicates dependencies of the electronic structure on the thickness of the flakes, which scatter differently various laser wavelengths (473 nm, 532 nm and 633 nm). Pulsed cathodoluminescence spectra of MoS2 nanocrystals under the action of high-energy electron pulse show an increase in the luminescence intensities with the increasing input of electron energy densities, where higher electron densities induce greater amount of electron-holes, which afterwards recombining release the energy in the form of luminescence. Irradiation of nanocrystals at maximum electron energy density of 200 mJ cm−2 leads to a strong luminescence band at 655 nm (1.88 eV), which is explained by recombination of A exciton. The luminescence decay kinetics of the nanocrystals under the action of different electron energy densities is presented.