Electronic and optical characteristics of 5d-transition metal doped 2D-NbSe2 monolayer for nanoelectronic device applications: An ab-initio-analysis

Abstract

Novel physical properties can be realized in 2D transition metal dichalcogenides (TMDCs) 2H-NbSe2 via chemical doping. Using first-principles calculations, we have investigated the electronic and optical properties of pristine and 5d-transition metal atoms (M = Hf, Ta, W, Re, Ir, and Pt) doped 3 × 3 supercells of NbSe2 monolayers. The physical properties of M-doped NbSe2 monolayers are found to be tunable upon doping with transition metals; making these modifications of NbSe2 attractive 2D materials for applications in nanoelectronics. The calculated electronic properties reveal that transition metal doping remarkably affects the electronic structures because charge transfer varies only due to 5d-transition metal substitution instead of Nb atom. Consequently, variation in the density of states around Fermi level (EF) is observed. A hybridization between 5d-states of transition metals (TM) and 4p states of Se results TM-Se covalent bonds. Hence, doping can significantly tune the electronic properties of NbSe2 monolayer. The optical properties such as optical absorption coefficient, optical conductivity, reflectivity and energy loss function are also computed and discussed for 2D applications of the studied TM doped NbSe2 monolayers. In particular, our results indicate that the absorption spectra shift to lower photon energies upon TM doping. Such tuning of the physical properties suggest the use of these 2D-materials with graphene, to fabricate viable electronic devices, such as logic circuits and field-effect transistors.