The Anh Le, Catalan Francesca Celine I, Kim Yousoo, Einaga Yasuaki, Tateyama Yoshitaka
Center for Green Research on Energy and Environmental Materials (GREEN) and International Center for Materials Nanoarchitectonics (MANA), National Institute for Materials Science (NIMS), 1-1 Namiki, Tsukuba, Ibaraki 305-0044, Japan.
Surface and Interface Science Laboratory, RIKEN, 2-1 Horosawa, Wako, Saitama 351-0198, Japan.
Phys Chem Chem Phys. 2021 Jul 28;23(29):15628-15634. doi: 10.1039/d1cp00689d.
Boron-doped diamond (BDD) has attracted much attention in semi-/superconductor physics and electrochemistry, where the surface structures and electronic states play crucial roles. Herein, we systematically examine the structural and electronic properties of the unterminated and H-terminated diamond(111) surfaces by using density functional theory calculations, and the effect of the boron position on them. The surface energy increases compared to that of the undoped case when the boron is located at a deeper position in the diamond bulk, which indicates that boron near the surface can facilitate the surface stability of the BDD in addition to the H-termination. Moreover, the surface energy and projected density of state analyses suggest that the boron can enhance the graphitization of the pristine (ideal) unterminated (111) surface thanks to the alternative sp2-sp3 arrangement on that surface. Finally, we found that surface electronic states depend on the boron's position, i.e., the Fermi energy (EF) is located around the mid-gap position when the boron lies near the surface, instead of showing a p-type semiconductor behavior where the EF lies closer to the valence band maximum.
硼掺杂金刚石（BDD）在半/超导物理学和电化学领域引起了广泛关注，其中表面结构和电子态起着至关重要的作用。在此，我们通过密度泛函理论计算系统地研究了未终止和氢终止的金刚石（111）表面的结构和电子性质，以及硼位置对它们的影响。当硼位于金刚石体相中较深位置时，与未掺杂情况相比表面能增加，这表明除了氢终止外，表面附近的硼可以促进BDD的表面稳定性。此外，表面能和态密度投影分析表明，由于该表面上交替的sp2-sp3排列，硼可以增强原始（理想）未终止（111）表面的石墨化。最后，我们发现表面电子态取决于硼的位置，即当硼位于表面附近时费米能（EF）位于带隙中间位置附近，而不是表现出EF更接近价带最大值的p型半导体行为。
