Charge carrier recombination centers in high-purity, dislocation-free, float-zoned silicon due to growth-induced microdefects

Abstract Swirl defects (A- or B-type) and frozen-in defects are found to be carrier recombination centers in dislocation-free, as-grown, float-zoned Si crystals. The A-type defect has an effective carrier capture range of ∼ 40 μm, as determined by EBIC analysis. The activation energy for forming the fast cooling frozen-in defects was estimated to be about 0.31 eV. Hydrogen doping can suppress swirl defect formation but causes other recombination centers. Defect formation can be changed by growth conditions, and long minority charge-carrier lifetimes are achieved through moderately high growth speeds and low thermal gradients during crystal growth, by which both swirl-defects and frozen-in defects are avoided.