Characterization of helium bubbles in Si by slow positron beam

Abstract

High-dose He-ion-implanted Si has been studied by positron annihilation method. As well known, due to post-implantation annealing at 1173 K, the positron lifetime and the Doppler broadening S parameter dramatically increased due to the formation of microvoids. Meanwhile, the post-implantation annealing at 573K resulted in a significant decrease in the positron lifetime and an apparent modification of the Doppler broadening spectrum near the momentum region of p=0.01 m0c. From the first principles calculation, we confirmed the positron trapping at He bubbles formed in large vacancy clusters. © 2010 IOP Publishing Ltd.