BLUE-VIOLET ELECTROLUMINESCENCE AND PHOTOCURRENT SPECTRA FROM POLYCRISTALLINE CHEMICAL VAPOR DEPOSITED DIAMOND FILM

We have measured current-voltage characteristic, blue-violet electroluminescence (EL) and subgap photocurrent spectra of free standing polycrystalline chemical vapor deposited diamond film. The current increases as a power law function of the voltage with an exponent of about 5.5. The EL spectra show a main luminescence band peaked at 3.0 eV, whose intensity increases linearly with the electric current. The photocurrent increases rapidly with the photon energy in the range from 2.0 to 3.5 eV and then tends to saturate. It is found that all these results can be consistently explained in relation to gap states centered at 3.0 eV above the valence band.