Dissertação de Mestrado #628 – Anna Carolina Marx Gonçalves – 13/08/2019

Transition metal dichalcogenides, like MoS2, have attracted a lot of attention in the last decade, due to the fact that they are layered semiconductors with an energy gap in the near infrared/visible, opening the way to many technological applications and fundamental studies. In this work we investigate the optical properties of MoS2 single layers both suspended and supported on a SiO2/Si substrates. Photoluminescence (PL) and Raman spectra were taken as a function of temperature from 7K to 300K in vacuum. We see significant differences in the PL spectra of the suspended and supported samples. In addition to the well-known excitonic features, called A and B in the literature, we observe emission from charged excitons (trions). We present and explain the evolution of these emissions as the temperature changes. At low temperature two new features become more noticeable and we attribute them to bound excitons.