Extremely high-efficient activation of acceptor boron introduced by ion implantation at room temperature with various doping concentrations in epitaxially synthesized diamond films by chemical vapor deposition

Abstract

We homoepitaxially synthesized a pure diamond film on type Ib base substrates by microwave plasma-assisted special chemical vapor deposition method and then doped B impurity atoms by the ion implantation technique with various doping concentrations from 2×1017 to 2×1019 cm−3 at room temperature followed by activation annealing at 1300 °C. The electrical properties of specific resistance, carrier concentration, Hall mobility, and conductive carrier type were analyzed by Hall effect measurements based on the van der Pauw method at sample temperatures from 77 to 873 K. We consequently realized excellent B-doping in the CVD-synthesized diamond film with a low compensation ratio and perfect doping efficiency and confirmed p-type conduction at almost all temperature ranges for the measured samples. In very lightly doped diamond, we observed first the existence of deep acceptor levels located near 1.85 eV with respect to the valence band maximum and proposed a conduction mechanism based on hopping conduction in deep acceptor levels. We showed the availability of this doping process to high-efficient B doping with various acceptor concentrations in diamond. The great success achieved in the activation of acceptor B implanted in diamond with various doping concentrations should definitely contribute to the progress in the application of diamond-based power semiconductor devices.