Cathodoluminescence measurement of CVD diamond surface

The surfaces of undoped homoepitaxial diamond films were investigated by cathodoluminescence (CL) measurement. The sample was grown by ECR microwave plasma-assisted CVD (ECR MPCVD) apparatus. The particular importance of this work is the surface treatment of the diamond surface by hydrogenation, oxidation and fluorination (CaF$ contact), with which the surface pinning level changed, giving rise to a characteristic relationship between the CL intensity and the electron beam energy. CL from the natural diamond was also observed. After the exposure of hydrogen plasma to natural diamond by applying 70 V bias voltage, the CL intensity from this surface became weak. This surface was thought to be damaged by hydrogen plasma. This result also suggests that during diamond growth by ECR MPCVD, the grown film is always irradiated with plasma and imposed damage. By lowering the bias voltage, diamond damage was reduced and at zero bias there was no sign of damage. These findings will be the key to the fabrication of high quality thin film.