First-principles Study on Optical Properties Modulation of GeSe Monolayer by Substitutional Doping

Substitutional doping can introduce substantial improvement in optical properties of atomically thin two-dimensional materials which in turn boosts device performance significantly. In this paper, we have explored the impact of group III, IV, V and VI dopants on the optical properties of GeSe monolayer using first-principles calculation for a doping concentration of 4.17%. Our study demonstrates an increase in static dielectric constant for all the dopants except for Sn with an approximate highest value of 14 and 8 in zigzag and armchair direction, respectively. Shifts in peaks of imaginary part of the dielectric function are observed upon doping along with modulation in values being highest for Te dopant in both types of substitutions. Refractive index increases mostly in red and infrared region for the dopants providing a value of greater than 3 when Ge is substituted by group VI dopants. Optical conductivity remains stable for all the dopants thereby retaining the original current density of pristine GeSe monolayer. All of these results encourage the applications of GeSe monolayer in next-generation optoelectronic devices.