Evidence of oxygen-stabilized hexagonal interstitial erbium in silicon

We report on the effects of codoped oxygen and thermal annealing on the evolution of lattice sites of erbium in silicon. At low concentrations of codoped impurities, it is evident that Er prefers occupation of the tetrahedral (T) interstitial site after Er ion implantation. Oxygen codoping can substantially populate implanted Er atoms onto the hexagonal (H) interstitial site. In the presence of oxygen, Er can be stabilized on the H site during annealing up to 900 °C. Also interesting is that post-implantation annealing can greatly promote occupation of the H site by Er in O-deficient Si, even though few Er atoms are found to be on the H site following Er ion implantation.