Mossbauer study of the proximity gettering of ion-implanted Co-57 impurities by B-Si precipitates in Si

We have studied the gettering of ion-implanted Co-57 impurities to amorphou s B-Si precipitates in B-implanted c-Si using Mossbauer spectroscopy in con junction with Secondary Ion Mass Spectroscopy and Transmission Electron Mic roscopy. Under high-temperature annealing, the Co atoms migrate from their as-implanted state to a gettered state at the B-Si precipitates in the B-im planted layer, while no association between the Co impurities and unprecipi tated B is observed. The gettered Co atoms clearly occupy a non-metal-silic ide site. The Mossbauer spectrum displays a pronounced quadrupole splitting , closely conforming to the spectrum observed for bulk crystalline B3Si imp lanted with Co. We therefore tentatively argue that the gettered atoms resi de at solution sites within the precipitates and not in their periphery, in agreement with previous indications.