Electroreflectance and reflectance study of 2H-MoSe2

We report the first electrolyte electroreflectance (EER) study of 2HMoSe₂ in the energy range 0.7 to 6 eV. The reflectivity (R) was also measured in the range of 0.7 to 9.5 eV and the real and imaginary parts of the dielectric constant were determined using the Kramers-Kronig relations. All the measurements were done at room temperature. Single crystals of 2H-MoSe₂ were grown using the direct combination of the elements in a sealed silica tube combined with chemical vapor transport using Br as the transport agent. The EER spectrum exhibits sharp structure in the vicinity of the excitonic transitions A, A′, B and B′ as well as higher lying interband transitions; the transition energies are determined with better accuracy than has been possible to date. A comparison of the R and EER spectra helped identify the various features in the EER spectrum.