Defect spectroscopy of nanodiamond thin layers

Fourier transform photocurrent spectroscopy (FTPS) has been applied to the study of electronic defect states in nanocrystalline diamond films. To analyze the influence of the substrate on submicron-thin nanodiamond films, silicon substrates were compared to low alkaline glass substrates. We have observed four peaks in the photocurrent spectrum of nanocrystalline diamond: two sharp peaks at 0.36 and 0.40 eV and broad bands at 0.27 and 0.57 eV. These peaks, observed for films grown on Si substrate, have different behavior with respect to the temperature, external light illumination and absorption/desorption processes at the nanodiamond surface.