Boron-deuterium complexes in diamond: How inhomogeneity leads to incorrect carrier type identification

The electrical properties of boron doped diamond layers after deuterium diffusion have been investigated by Hall effect and capacitance voltage measurements. It is found that (i) the deuterated boron doped diamond layers are inhomogeneous after the deuterium diffusion, resulting in conducting and insulating areas; (ii) negative and positive Hall voltages are measured on the same boron doped sample after deuterium diffusion, depending on the contact geometry (negative with van der Pauw and positive with mesa etched Hall bar); and (iii) in the conducting area, the majority of the boron-deuterium complexes are not ionized after the deuterium diffusion. The detailed electrical measurements using mesa-insulating Hall bar structures revealed that the existence of inhomogeneous regions with conducting and insulating areas is the most probable source of wrong n-type conductivity in deuterated boron doped diamond layers of this work. In the light of this result, the possibility of an incorrect assignment of a shallow donor previously reported in deuterated boron doped diamond is discussed. Finally, confirmation is given that the boron deuterium complexes created after the deuterium diffusion are neutral in p-type diamond. (C) 2011 American Institute of Physics. [doi: 10.1063/1.3611035]