Results are presented of a study of {113}-defect formation in Si nanowires withdiameters ranging from 50 to 500 nm. The Si nanowires, used for the processingof tunnel-FET's, are etched into a moderately doped epitaxial Si layeron a heavily doped n-type Si substrate. {113}- defects are created in situ by 2MeV e-irradiation at temperatures between room temperature and 375 °Cin an ultra high voltage electron microscope. The observations are discussed inthe frame of intrinsic point defect out-diffusion and interaction with dopantatoms.