Transport properties of B and N sites vacancy defects graphene/h-BN heterostructures: First-principles study

First-principles calculations based on spin-polarized DFT-D2 approach have been carried out to study the transport properties of graphene/h-BN (G/h-BN) heterostructure (HS), 1 N vacancy defect in G/h-BN (G/h-BN_1 N), nearest neighbour of 1 N & 1B vacancy defects in G/h-BN (G/h-BN_nBN), and alternate zone of 1 N & 1B vacancy defects in G/h-BN (G/h-BN_aBN) materials. Transport properties like electrical conductivity (σ), electronic contribution of thermal conductivity (K), Seebeck coefficient (S) and thermoelectric power factor (P) are estimated through Boltzmann transport equations (BTE) within constant relaxation time approximation (RTA). Quantum ESPRESSO and BoltzTrap packages are used as a computational tool in the calculations. The considered materials are found to be stable van der Waals (vdWs) HS. The σ and K of graphene, h-BN, G/h-BN, G/h-BN_1 N, G/h-BN_nBN and G/h-BN_aBN are found to be increasing monotonically with temperature. The defected materials have slightly less value of σ than that of G/h-BN due to the effect of their effective mass and carrier concentration. At room temperature, K of G/h-BN, G/h-BN_nBN and G/h-BN_aBN retains similar value, while K of G/h-BN_1 N has increased slightly because the increase in Fermi velocity of electrons near Fermi level due to the reduction in effective mass thereby increasing the mean free path. We have analyzed the temperature dependent (constant value of energy) and energy dependent (constant value of temperature) S and P of above-mentioned materials, and found that S and P of defected HS are higher than that of non-defected HS materials due to combine dependence of n, T and m* on the value of S. The estimated S and P values of considered materials are consistent with reported value. Hence, they have budding employment in the thermoelectric devices.