ELECTRICAL-CONDUCTIVITY STUDIES OF DIAMOND FILMS PREPARED BY ELECTRON-CYCLOTRON-RESONANCE MICROWAVE PLASMA

The electrical conductivity of diamond films, having different surface morphologies, was measured in the temperature range from 200 to 800-degrees-C. The films were prepared by the electron cyclotron resonance plasma-assisted CVD method (ECR-PACVD) using CO/H-2/O2. We found that films with (111) surface morphology have electrical conductivity activation energies of between 0.3 and 0.4 eV, consistent with boron ionization energy in diamond. On the other hand, films with (100) morphology have an activation energy of 1.5 eV, consistent with the ionization energy of substitutional nitrogen. Due to their high solubility, boron and nitrogen are the most common impurities in natural and synthetic diamond. These data suggest that electrically active boron and nitrogen incorporation is correlated with the film growth along (111) and (100) directions, respectively.