Effect of Gold Dopant on Structural and Optical Properties of Molybdenum Disulfide Single Crystals

摘要

Single crystals of MoS_2 doped with gold (MoS_2: Au) have been grown by the chemical vapor transport method using iodine as a transporting agent. The transmission electron microscopy (TEM) images showed that doping sites and migration behaviors of Au atoms moved around t.he MoS_2 and jumped with different positions. The doping effects of the materials were characterized by temperature-dependent piezoreflectance (PzR) spectroscopy measurements at temperature of 25 to 300 K. The temperature dependence of the spectral features in the vicinity of direct band-edge excitonic transition of the Au-doped and undoped one was figured out. The energies and broadening parameters of the A and B excitons have been determined accurately via a detailed line shape fit of the PzR spectra. The parameters that describe the temperature variation of the energies and broadening functions of the excitonic transitions are analysed. In addition, the origin of these excitonic transitions is evaluated and discussed. A plausible suggestion will be put forth to explain the role of gold in affecting the variation of the excitonic transitions.