A study of He+ ion-induced damage in silicon by quantitative analysis of charge collection efficiency data

Abstract The ion damage is responsible for the progressive reduction of the collection efficiency of a semiconductor device in Ion Beam Induced Charge (IBIC) measurements. This effect was studied by irradiating a silicon n + -p diode with a 1.85 MeV He + microbeam at very low fluences ≤5 × 10 9 ions/cm 2 and measuring the decrease of charge pulse height vs ion fluence. The experimental results can be described by a model, which represents the region of maximum damage as an interface with given carrier recombination velocity v s . The model assumes that the ion fluence affects v s , but not the bulk minority carrier diffusion length. The comparison between experiment and theory yields an approximately linear relationship between ion fluence and v s ; this yields a value of about 7 for the average number of recombination centers produced by a single He + ion.