Charge transport in polycrystalline and single crystal synthetic diamond using ion beam induced charge imaging

Ion beam induced charge (IBIC) imaging has been used to investigate charge transport in high quality polycrystalline CVD diamond and single crystal synthetic diamond. In polycrystalline material the intra-crystallite charge transport within single crystals was studied. Micrometer resolution images of charge signal amplitude in different regions of a diamond crystallite are obtained as a function of the electric field strength. The charge signal amplitude, which is directly related to charge carrier drift length, is correlated to the distribution of radiative centres in the diamond identified using cathodoluminescence imaging. By comparison, IBIC imaging of single crystal synthetic diamond was also carried out. The sample, which contained deliberately introduced nitrogen lines, showed electron and hole CCE values close to 100%, in the low nitrogen regions. By comparison with CL and UV luminescence images, direct evidence is observed for the role of nitrogen and dislocations as deep trapping centres and their reduction of both electron and hole lifetimes.