Measurements of Defect Density Inside CVD Diamond Films Through Nuclear Particle Penetration

Abstract

Fast nuclear particles (light or heavy ions), passing through a diamond film, deposit energy by ionization. It is possible to collect the developed charges by applying an electric voltage through both sides of the film. Experimental results show that the positive hole charges and the negative electron charges have very different mean free paths inside a real diamond film. Holes travel more deeply than electrons, so that the charges collected under a given voltage and under the opposite one are very different, as a suitable “two fluid” microscopic model of electrical conduction of the film can show. Furthermore, using fast particles of different penetration produced by a Tandem accelerator, it is possible to obtain a “photograph” of the differential charge collection, which can show the distribution of charge production (through the Bragg’s ionization curve) and destruction (through the defects, and therefore on defect density along the particle path). Minimization of this defect density allows us to optimize the deposition procedure of CVD diamonds.