Temperature dependence of energies and broadening parameters of the band-edge excitons of Mo1-xWxS2 single crystals

We have measured the temperature dependence of the spectral features in the vicinity of direct band-edge excitonic transitions of Mo1-xWxS2 single crystals from 25 to 300 K using piezoreflectance (PzR). From a detailed lineshape fit of the PzR spectra, the energies and broadening parameters of the A and B excitons have been determined accurately. The origin of these excitonic transitions is discussed. The transition energies and their splittings vary smoothly with the tungsten composition x, indicating that the natures of the direct band edges are similar for the Mo1-xWxS2 compounds. In addition, the parameters that describe the temperature variation of the energies and broadening function of the excitonic transitions are evaluated and discussed.