Defect Reaction and Electrical Properties of Iron in N-Type Silicon

Since the first report by our group in 1992, iron-related defects in n-type silicon has been found to exhibit unusual in-diffusion and annealing properties. We review in this paper the recent progress in understanding the electrical and diffusion properties of iron-related defects in n-type silicon. We have shown from DLTS and Hall effect that iron in n-type silicon is electrically ionized and introduce one donor level at Ec-0.41 eV (level C) and, at least, one acceptor level at Ec-0.21 eV (level B). The donor character of former level has been confirmed by a Poole-Frenkel effect. The concentrations of two centers introduced are in the order of 1013 cm−3 at maxima. In-diffusion behavior of levels B and C show that these levels are intermediate states in a consecutive reaction of iron-related complex formation. Low-temperature isothermal annealing experiments from the room temperature to 200°C suggest that iron-related donor is formed, in part, by the electrostatic attractive force between two point charges.