Deuterium-induced passivation of boron acceptors in polycrystalline diamond

In monocrystalline boron-doped diamond (BDD), the diffusion of deuterium induces an electrical passivation of acceptors by the formation of (B,D) complexes. However, device applications based on this process are presently limited by the small size of available monocrystalline substrates. In this work, we show that the grain size of polycrystalline diamond is a key parameter in order to achieve efficient deuterium diffusion by trapping on boron atoms. As a result, we present the first clear evidences of the electrical passivation of boron acceptors in the case of polycrystalline diamond layers with an average grain size of 50 mu m. We show that, for a boron concentration of 2 x 10(19) cm(-3), the room temperature hole mobility increases from 70 to 120 cm(2) V(-1) s(-1) after deuteration. More surprisingly, the compensation ratio keeps the same order of magnitude which suggests a passivation effect on both acceptors and donors. (C) 2010 American Institute of Physics. [doi: 10.1063/1.3518608]