THE NATURE OF EXTRINSIC PHOTOCONDUCTIVITY IN DIAMOND THIN-FILMS

While extrinsic photoeffects in chemically vapour-deposited thin films of diamond can originate from impurity-controlled photogeneration and photoinjection of carriers from contiguous metal electrodes, it is important, and yet difficult, to differentiate between these two distinctive processes. Detailed studies and results are described, involving the use of non-absorbing water-based electrodes which allow a clear distinction between these two mechanisms to be made. In addition, the near-infrared-visible photoeffect in diamond thin films, as in single-crystal diamond, is associated with the photoionization of unionized acceptors based on its observed quenching in nitrogen-doped compensated films.