Optical characterization of two-dimensional semiconductors

Abstract This chapter introduces the optical characterization of two-dimensional (2D) semiconductors by Raman spectroscopy, photoluminescence (PL) spectroscopy, and absorption spectroscopy. It starts by presenting how Raman spectroscopy can be utilized to characterize the properties of 2D semiconductors such as crystal structures, strain, doping, defects, thermal conductivity, electronic band structures, and so on. Then basic exciton properties of 2D semiconductors including neutral excitons, charged excitons, bounded excitons, biexcitons and the effects of electrostatic gating, chemical doping, strain, magnetic field, circular polarized light, and substrate on these excitonic structures explored by PL spectroscopy are elaborated. Besides basic excitonic emission, single-photon emission, stimulated emission, and dark excitons of 2D semiconductors are reviewed. Moreover, absorption investigations on 2D semiconductors are also discussed where steady-state absorption features and transient absorption properties of 2D semiconductors are included.