  Boron-doped diamond (BDD) has attracted much attentions in
semi-/super-conductor physics and electrochemistry, where the surface
structures play crucial roles. Herein, we systematically re-examined the
probable surface reconstructions of the bare and H-terminated BDD(100) and
(111) surfaces by using density functional theory (DFT). For the optimized
structures, we performed STM image simulations based on Tersoff-Hamman scheme
and calculations of the projected density of states. We found that: on the
BDD(100), the p(2x1) reconstruction has lowest energy and the c(2x2)
reconstruction has 0.1673 eV/surface-atom energy higher; On the BDD(111), the
ideal (1x1) has lowest energy, the single chain SC-(2x1) and Pandey chain
PC-(2x1) have 0.3415 eV/surface-atom and 0.6576 eV/surface-atom higher energy,
respectively. The BDD(111) appears to have more reconstructions than the
BDD(100) which supports to the idea that the BDD(111) is more electrochemically
reactive than the BDD(100). In addition, we study the impact of the Boron
dopant on the surface states of the BDD(111) and suggest the Boron-enhanced
graphitization on the BDD(111). The results give an insight into the surface
stability of the BDD.
