Enhancement of p-type conductivity of monolayer hexagonal boron nitride by driving Mg incorporation through low-energy path with N-rich condition

We report a low-energy path to enhance the incorporation of Mg on the V-B site in monolayer hexagonal boron nitride (h-BN) by an N-rich condition for effective p-type conductivity. Density functional theory calculations reveal that V-B and Mg-B both behave as a shallow acceptor for p-type conduction of h-BN. The N-rich condition is found to promote the formation of V-B as a low-barrier site for Mg-B incorporation. Experimentally, Mg p-type doping is achieved in a h-BN monolayer under N-2 (or NH3) gas flow through a chemical vapor deposition method. The surface current of Mg-doped h-BN has been enhanced by three times up to 32 mu A under a 8V external voltage. This approach provides excellent p-type conductivity in monolayer h-BN for future applications in two-dimensional optoelectronic devices.