Boron-Doped Diamond Film Homoepitaxially Grown on High-Quality Chemical-Vapor-Deposited Diamond (100)

In this study, high-quality homoepitaxial diamond (100) without any growth hillocks or abnormal particles has been investigated as a buffer layer for boron-doped diamond overgrowth to improve the electrical properties. For the undoped buffer layer used, very strong band-edge emissions were observed at room temperature (RT) in the cathodoluminescence (CL) spectra. After the overgrowth of B-doped homoepitaxial layer, CL characteristics and electrical properties were compared with cases when diamond buffer layers with inferior quality from the viewpoint of CL spectra were employed. The results showed that employing such a high-quality buffer layer led to an efficient acceptor doping of B atoms of 1.6×1019 cm-3 to the overgrown layer while the RT hole mobility was kept at 910 cm2/Vs, although bound-exciton CL peaks were well resolved only at lower temperatures. The usefulness of the high-quality buffer layer is discussed.