Electrical properties of iron-related defects (IRD) introduced in n-type floating zoned (FZ) and Czochralski (CZ)-grown silicon are studied by deep level transient spectroscopy and Hall effect. Electrically active IRD have been observed for the first time in n-type CZ silicon. Enthalpy and entropy factors of electron emission rate of IRD are equivalent between those observed in CZ and FZ silicon. In-diffusion process at 1160° and isothermal annealing process at 150° also indicate the identical nature of IRD between CZ and FZ silicon, which can be understood in terms of the consecutive progress of iron-related complex-formation reactions including interstitial iron atoms (Fei) in the silicon crystal. The IRD is independent of oxygen and phosphorus atoms. Only a small fraction of Fei forms electrically ionizable complexes