Structural and electronic properties of AlY (Y B, N, O) dual-doped twin graphene: A density functional theory study

Abstract

Twin graphene is a novel two-dimensional semiconducting carbon allotrope with an intrinsic direct bandgap. To explore the excellent properties and potential applications of twin graphene, we performed first-principle density functional theory calculations on the structural, electronic, and magnetic properties of twin graphene with dual-doping of Al and Y (YB, N, O) atoms at different sites (ortho, meta, and para). The combined processes of the formation of all Al–Y dual-doped twin graphene (AlY-TG) systems are exothermic and form stable dual-doped structures, and the most stable structure is the AlB-TG system. For the B, N, or O atoms at the same doped site, the stability decreases in the order of AlB-TG, AlN-TG, and AlO-TG. Dual-doping regulates the bandgap of twin graphene in the cases of AlB and AlN doping. A transition from a semiconducting material into a metal is observed when AlO doping is used, while a transition from a direct semiconductor into an indirect semiconductor is observed for AlB doping at the ortho site. Different magnetic moments of the AlY-TG systems are observed for different Y atoms placed at different doping sites. The AlN-TG system remains nonmagnetic, while the AlB-TG system has a magnetic moment of 1.01 μB only in the meta site, and the AlO-TG systems have magnetic moments of 0.50 μB and 0.56 μB in the ortho and meta sites, respectively. Moreover, different doping concentrations can effectively affect the electronic structures and magnetisms of the AlY-TG systems. For doping concentrations of 5.6% and 11.1% at the meta site, the AlB-TG systems exhibit metal characteristics with a high spin polarization. The results show that the electronic and magnetic properties of twin graphene can be modulated via Al–Y (YB, N, O) dual-doping, indicating that twin graphene has potential applications in nanomagnets and spintronics devices.