Abstract: High quality homoepitaxial diamond films were synthesized by microwave-enhanced plasma chemical vapor deposition MPCVD method and were characterized by scanning electronic microscopy (SEM) and cathode luminescence (CL) method. In order to obtain high film growth rate, the methane concentration (CH₄/H₂) was set at 4%. Although small pits existed on the films and their numbers depended on the growth condition, no unepitaxial crystals were observed from any sample grown in this study. CL spectra of these diamond films measured at room temperature revealed edge emission. The intensity was larger for sample with small number of pits. Aluminum contacts formed on these hydrogen terminated films showed p-type rectification properties. The breakdown voltage estimated between Al Schottky contacts and Ti/Au Ohmic contacts with 500 μm in separation was 380 V in spite of no electrode grading structure. These results indicate that the gap states confirmed from CL spectra relate strongly to the breakdown voltage of Schottky contacts.