Electronic properties tailoring of th-XN (X = B, al) by surface functionalization

Abstract

Hydrogenation and fluorination is a significant method to tune the electronic properties of two-dimensional (2D) materials. This paper theoretically predicted and analyzed the effects and regulatory mechanisms of surface functionalization on the electronic properties of 2D semiconductor tetrahex Boron/Aluminium Nitride (th-BN/th-AlN). The density-functional theory (DFT) calculations were employed to study various trends of band structure, effective mass, and work function. The results show that the electronic properties of 2D th-BN/th-AlN are susceptible to the surface adsorption atom species and coverage. Interconversions between semiconductor and metal properties or indirect and direct band structures in 2D th-XN (X = B, Al) can be realized by hydrogen and fluorine surface adsorption. The band gap expands and the work function decreases after H atom is adsorbed on the surface, while the band gap first increases and then decreases and the work function expands after F is adsorbed on the surface. After functionalization, the effective mass of the hole will be reduced to even lighter than that of an electron in certain directions. The change mechanisms of electronic properties in th-BN/AlN is surface adsorbed atoms will cause sp2-hybridized atoms to turn into sp3-hybridized atoms, which leads to the polarized double bonds between adjacent atoms becoming a single σ bond. The chemical bond changing will result in the band near the Fermi level gradually disappearing.