The solution of iron in silicon

Abstract

The solution of iron in silicon has been examined by instrumental neutron activation analysis (NAA) and EPR of quenched samples. It was possible to obtain the total iron concentration and the concentration of interstitial iron for each specimen as a function of temperature. During the heat treatment of any silicon sample, iron from random sources diffuses into the silicon in a two‐step process; the second step can be suppressed by the use of a nonreducing atmosphere. At 1100 °C iron‐coated samples show saturation of the iron concentration already after about 30 min. The NAA and EPR of samples saturated with iron lead to the same slope of concentration versus 1/T. From this, it is concluded that most likely both experiments measure the interstitial iron species so that the substitutional solubility has to be lower than that for the interstitial with 2.90.05 eV being the enthalpy of formation of a neutral interstitial iron atom in silicon.