Structure, Thermodynamics, and Raman Spectroscopy of Rhenium-Doped Bulk MoS₂ from First Principles

Abstract

Doping MoS 2 with Re is known to alter the electronic, structural, and tribological properties. Re-doped MoS 2 has been previously mainly studied in the monolayer or few-layer form but can also be relevant for applications in the many-layer or bulk form. In this work, we use density functional theory to explore the structure, phase stability, and Raman spectrum of bulk Redoped MoS 2 . We consider the possibility of the Re dopant existing at different locations and provide experimentally distinguishable characteristics of the most likely sites: Mo substitution and tetrahedral (t-) intercalation. We demonstrate and benchmark a general approach to calculate Raman spectra of doped materials with metallic densities of states by using atomic Raman tensors from the pristine material. Upon applying this method to the metallic Re-doped structures, we find characteristic shifts in the Raman-active peaks depending on the Re dopant position: red shifts in both A 1g and E 2g 1 peaks in the t-intercalated case versus a red shift for A 1g and a blue shift (sometimes accompanied by a smaller red-shifted peak) for E 2g 1 peaks in the Mo-substituted case, which can be used to identify the dopant sites in experimental samples. We analyze the interactions giving rise to these shifts.