IBIC investigation of radiation-induced effects in CVD and natural diamond

A report is presented concerning the results obtained by Ion Beam-Induced Current (IBIC) investigations about the effects of radiation both on CVD and in natural diamond. Proton microbeam itself is used both to irradiate and to “probe” diamond samples particularly in their cross-sections as obtained by cleaving (“lateral IBIC”). Proton fluences and corresponding doses are limited normally to 108 p/cm2 and to 2 Gy, respectively, leaving the possibility of an order of magnitude more. While in natural IIa diamond samples the charge collection efficiency is homogeneously distributed and it homogeneously increases as a function of proton dose, in CVD diamond samples it is not homogeneously distributed, it reflects the morphology of the samples and the main effect of irradiation is both to increase and to spread it over the low collection efficiency regions. Moreover, transient polarisation effects leading to lower collection efficiencies are reported both for CVD and diamond samples, in a way that seems to be dependent on the count rate registered by the “probe” beam.