Defects in Irradiated Silicon: Electron Paramagnetic Resonance and Electron-Nuclear Double Resonance of the Arsenic- and Antimony-Vacancy Pairs

Abstract

Two EPR spectra are observed in irradiated silicon (designated Si-$G23$ and Si-$G24$) which are identified with the neutral charge states of a lattice vacancy adjacent to a substitutional arsenic or antimony atom, respectively. EPR and ENDOR studies reveal a high degree of similarity between these defects and the phosphorus-vacancy pair (Si-$G8$) studied previously. Nuclear quadrupole interactions for the As and Sb atoms give additional information about the defect configuration, not available for the phosphorus-vacancy pair. For all three defects, a large static Jahn-Teller distortion occurs. Analysis of the response of the defects to externally applied stress allows an estimate of \ensuremath{\approx}1 eV for the magnitude of the Jahn-Teller stabilization energy. It is concluded that this energy is larger than the electron-electron interaction energies and comparable to (or greater than) the crystal-field energies for the electrons involved in the core of the defects. Studies of the group-V atom-vacancy reorientation kinetics reveal variations between the three defects that can be correlated with the elastic interactions between the oversize arsenic or antimony atoms and the tensile strain around the lattice vacancy. Comparison of the results with the annealing studies of electrical properties by Hirata et al. indicate that the annealing of each defect involves the migration of the pair as an entity through the lattice.