Superconducting properties of homoepitaxial CVD diamond

Superconductivity was achieved above 10 K in heavily boron-doped diamond thin films deposited by the microwave plasma-assisted chemical vapor deposition (CVD) method. Advantages of the CVD method are the controllability of boron concentration in a wide range, and a high boron concentration, compared to those obtained using the high-pressure high-temperature method. The superconducting transition temperatures of homoepitaxial (111) films are determined to be 11.4 K for TC onset and 8.4 K for zero resistance from transport measurements. In contrast, the superconducting transition temperatures of (100) films TC onset = 6.3 K and TC zero = 3.2 K were significantly suppressed.