Raman investigation of InSe doped with GaS

The Raman spectrum of InSe doped with GaS exhibits appreciable changes at low doping densities indicating considerable changes on introducing GaS. The photoluminescence as well as resonance Raman study shows that the exciton energy is shifted towards higher energy as a result of doping. At resonance, both the one- and two-phonon polar modes are observed, although considerably broadened. This indicates that the GaS-doped InSe develops significant topological disorder. Resonance Raman study shows that increasing the dopant broadens the resonance but the excitonic energy does not change as a result of the increase in the GaS in InSe. The scattering also exhibits considerable temperature dependence, so that it is possible to temperature tune the resonance in the doped samples at low temperatures.