A STUDY OF HE-INDUCED DAMAGE IN SILICON BY QUANTITATIVE-ANALYSIS OF CHARGE COLLECTION EFFICIENCY DATA( ION)

The ion damage is responsible for the progressive reduction of the col lection efficiency of a semiconductor device in Ion Beam Induced Charg e (IBIC) measurements. This effect was studied by irradiating a silico n n(+)-p diode with a 1.85 MeV He+ microbeam at very low fluences less than or equal to 5 x 10(9) ions/cm(2) and measuring the decrease of c harge pulse height vs ion fluence. The experimental results can be des cribed by a model, which represents the region of maximum damage as an interface with given carrier recombination velocity v(s). The model a ssumes that the ion fluence affects v(s), but not the bulk minority ca rrier diffusion length. The comparison between experiment and theory y ields an approximately linear relationship between ion fluence and v(s ); this yields a value of about 7 for the average number of recombinat ion centers produced by a single He+ ion. (C) 1998 Elsevier Science B. V.