Photoluminescence study of self-interstitial clusters and extended defects in ion-implanted silicon

Abstract

We report on the photoluminescence (PL) studies of self-interstitial (I) clustering in ion-implanted Si at various stages of post-implantation annealing. Low-temperature PL measurements on as-implanted and low-temperature annealed (up to 450°C) samples show sharp X and W bands at 1200 and 1218nm which are attributed to I4 and I3 clusters, respectively. Annealing at 600°C shows a drastic change in the PL spectra. In case of high-energy self-ion-implanted samples, 600°C annealing produces several peaks in the range 1250–1400nm. For longer duration annealing, two broad bands form at 1322 and 1392nm irrespective of the ion fluence. These PL signatures are attributed to I8 clusters and/or (100) I-chains, and they are believed to be the precursor of {311} rod-like defects. For annealing above 600°C and for fluence ⩾1×1013cm−2, a sharp PL band is observed at 1376nm and it is attributed to {311} rod-like defects. At higher fluences, an additional broad band appears in the PL spectrum at ∼1576nm which is related to residual ion-damage or extended defect formation. These results illustrate the potential of silicon I-clusters as a possible source of light emission from Si.