Three-dimensional site dependence of single-ion-induced charge collection at a p-n junction - Role of funneling and diffusion processes under different ion energy

The amount of charges induced by high energy single ion irradiation at a p-n junction diode has been measured and its dependence on the ion incident position has been evaluated by using single-ion microprobe technique. By irradiating single He ions with various incident energy (1.4 - 4.05 MeV), dependence of the profiles of collected charges on the ion incident energy has been investigated. Origins of the different profiles among the different incident energy are discussed in terms of different contribution of two mechanisms of charge collection, namely, field funneling and diffusion of carriers. In the case of the ion incidence within the junction area, dependence of the charge collection profile on the ion incident energy comes from different contribution of the funneling in the charge collection process, while difference in the collection efficiency of the diffused charges affects the profile in the case of the ion incidence at outside of the junction.