A new model of ‘‘new donors’’ is presented, based on electrical, infrared measurements, transmission electron microscopy, and high‐resolution electron microscopy observations on Czochralski‐grown silicon single crystals containing ‘‘new donors.’’ In this model, the electrical activity of ‘‘new donors’’ originates from the uncoordinated Si dangling bonds on small dislocation loops resulting from oxygen precipitation. In comparison with other models, the present model can better explain the experimental results of the heat treatment Czochralski‐grown Si wafers.