Semiconducting graphene nanoribbon retains band gap on amorphous or crystalline SiO_2

Electronic properties of a semiconducting armchair graphene nanoribbon on SiO_2 are examined using first-principles calculations and taking into account the van der Waals interaction. Unlike semiconducting carbon nanotubes, which exhibit variations in band gap on SiO_2, the nanoribbon is found to retain its band gap on SiO_2, regardless of the separation distance or the dielectric’s surface type—crystalline or amorphous. The interfacial interaction leads to electron-transfer from the nanoribbon to the dielectric. Moreover, for crystalline SiO_2, the quantity of electron-transfer and the binding energy depend strongly on the type of surface termination and weakly on the binding sites

DFT based study on structural stability and transport properties of Sr3AsN: A potential thermoelectric material

Antiperovskite materials are well known for their high thermoelectric performance and gained huge research interest. Here, we report the structural stability and transport properties of Sr$_3$AsN from a precise first-principles study. The calculated equilibrium lattice parameters are in a good agreement with the available data. We find that Sr$_3$AsN is a mechanically, energetically and dynamically stable at ambient condition. Our calculated electronic structure indicates that it is a direct bandgap semiconductor, with a value ~1.2 eV. Sr-4d and N-2p orbitals mainly formulate the direct bandgap. This antiperovskite possesses a high Seebeck coefficient. Although its lattice thermal conductivity is comparatively low, electronic thermal conductivity is very high. The calculated maximum TE figure of merit is 0.75 at 700 K, indicating that it is a potential material for thermoelectric applications.Comment: 22 pages, 11 figure