Geometrical non-uniformities in the sensitivity of polycrystalline diamond radiation detectors

Chemical vapour deposited (CVD) diamond is a remarkable material for the fabrication of photon and particle detectors. However, little is known about the perturbations induced by the polycrystalline nature of this material. For this purpose, we have used a micrometer size X-ray beam generated from a synchrotron light source to induce photocurrents in a CVD diamond-based detector. By comparing the measured currents in the device as the beam interaction position is moved on the sample with the topographical image of the surface observed using a scanning electron microscope (SEM), a significant non-uniformity has been observed that could be correlated with the grain structure.