On the fluence dependence of radiation-induced carrier removal in moderately doped Si

Two different empirical rules have been proposed for the fluence dependence of the radiation-induced carrier removal, i.e., the exponential rule and t he linear rule. In order to distinguish which rule is more adequate, in-sit u measurements of carrier concentration in moderately doped n-type Si have been carried out under 17 MeV proton irradiation. The results at T = 200 an d 300 K are well fitted by the linear relation, while the result at 450 K i s relatively well fitted by the exponential one. The experimental results a re reproduced by a numerical calculation based on the Oerlein model which i ncludes 15 reactions of 14 defect species. The change from the linear to th e exponential rule is mainly ascribed to increased thermal excitation of ca rriers from defect levels. (C) 1999 Elsevier Science B.V. All rights reserv ed.