Interaction of positrons with vacancy-oxygen complexes and oxygen clusters in silicon

The isochronal annealing behavior in O-ion-implanted Si has been investigated using variable-energy positron annihilation spectroscopy. For the 2x10(15) O+/cm(2) implanted Si, multivacancy-oxygen complexes induced by room temperature implantation are transformed into multivacancy-multioxygen ones around 600 degrees C. Annealing at 800 degrees C results in the formation of oxygen microclusters, whose concentration increases sublinearly with the dose over the range from 2x10(14)/cm(2) to 2x10(15)/cm(2). It is shown that the positron technique is very useful for the study of the oxygen-defect complexes in Si, which are not observable by transmission electron microscope, as well as the open-volume type defects.