Effect of boron on the superconducting transition of heavily doped diamond

We have performed electronic structure calculations by means of density functional theory combining plane-wave method with cluster method for the heavily boron-doped diamond. The results for an isolated boron center with different doping levels indicate an acceptor energy level apart from the top of the valence band, and the results for the heavily boron-doped diamond, considering the interaction of boron centers, show the impurity levels mixed with valence band edge and the Fermi level located in the valence band. Consequently, the results support a mechanism of the type of metal–superconductor transition and indicate the critical temperature Tc should be related to the B concentration.