The primed state of CVD diamond under blue light illumination

Broad beam IBIC measurements with 2 MeV protons have been carried out on CVD diamond as a function of temperature in order to investigate the effect of illumination (white and blue light) on charge collection properties of electrons, even in absence of a previous X-ray priming. The results indicate that there is no direct effect of the light, apart from a contribution to noise and that blue light has the effect of improving charge collection in low charge collection efficiency regions. The fact that there is no noticeable change of collection properties as a function of temperature excludes effects such as temperature assisted detrapping of carriers: the conclusion is therefore that optically assisted detrapping of electrons in disordered regions around the grain boundaries seems to be the dominant mechanism during blue illumination of CVD diamond.