Atomic scale study of boron interstitial clusters in ion-implanted silicon

Abstract

Monocrystalline silicon was implanted with boron (32 keV, 1.3×1015 at. cm−2), post-annealed (740°, 10 min, N2) and further analyzed at the atomic scale by atom probe tomography. A comparison between the as-implanted and annealed samples demonstrated the presence of large B–Si clusters after annealing which were associated with the well-known boron interstitial clusters. The cluster density (up to 5×1017 cm−3) and the number of B atoms per cluster (up to 50) were found to vary with the boron concentration. Only 8% of the B atoms were found trapped in those clusters, suggesting the presence of a majority of very small B–Si aggregates in correlation with simulations.