Piezoreflectance study of near band edge excitonic-transitions of mixed-layered crystal Mo(SxSe1-x)2 solid solutions

Abstract

The temperature dependence of the spectral features in the vicinity of the direct band edge of mixed-crystals Mo(SxSe1-x)2 solid solutions is measured in the temperature range of 25–295 K by using piezoreflectance (PzR). The near band-edge excitonic transition energies of Mo(SxSe1-x)2 solid solutions were determined accurately from a detailed line-shape fit of the PzR spectra. The near band-edge excitonic transition energies were found to vary smoothly with the increase of S content x, indicating that the natures of the direct band edges of Mo(SxSe1-x)2 solid solutions are similar. The temperature dependences of near band edge transition energies were analyzed using Bose-Einstein expressions in the temperature range from 25 to 295 K. The parameters that described the temperature variation of the energies and broadening function of the excitonic transitions were evaluated and discussed.