A coupling effects of vacancy and Al (Ga, In) dopant on electronic structures of hexagonal boron nitride monolayer

In this work, we have systematically investigated the electronic and magnetic properties of the h-BN monolayer with vacancy and Al (Ga, In) dopant using DFT. The results show that the dangling and weak bonds at the vacancy can induce some in-gap defective states and magnetic moment, and In dopant has more influence on electronic structures of h-BN than Al or Ga dopant does. For divacancy, the energies of defective states are sensitive to the vacancy concentration. Besides the under-coordinated atom at the vacancy, Al(Ga, In) atom can act as heteroatom to reestablish a balance between geometry and electron systems. For monovacancy defect, Al(Ga, In) dopant will couple with three under-coordinated atoms at the vacancy. The coupling with N is strong while the interacting with B is weak. The magnetic moments are reduced to zero. For divacancy defect, Al(Ga, In) dopant will bond with under-coordinated N atoms and leave under-coordinated B atoms, which induce the diversity of structure including the coordinated Al(Ga, In) dopant, and under-coordinated B (adatom) atom, as well as the interactions among under-coordinated B atoms and between N/B atom and Al(Ga, In) dopant. On the contrary to pristine divacancy, their electronic and magnetic properties are independent of concentration. In addition, for the vacancy with Al dopant, the electronic and geometric structures are sensitive to charge state due to requirement of a balance between geometry and electron systems.