Dominant defect levels in diamond thin films: A photocurrent and electron paramagnetic resonance study

Characteristic features in photocurrent (PC) and electron paramagnetic resonance (EPR) spectra are discussed and attributed to main defects in the gap of optical-quality chemical vapor deposited diamond. A shoulder in the PC spectra with an onset at about 2.2 eV is attributed to the single-substitutional nitrogen defect (EPR P1 resonance at g=2.0024). A second feature in the PC spectra with an onset of about 1.3 eV is observed on “as-grown” samples with a hydrogen terminated surface. The defect level associated with this feature is hydrogen related, and this defect disappears after oxidation of the diamond sample surface. The EPR g=2.0028, which was also suggested to be H-related, is discussed.