B implants of 1 keV, 1×1015 at. cm-2 into 125-nm-wide, free-standing Si nanostructures have been characterized using scanning spreading resistance microscopy following a 0 s, 1050 °C anneal in N2. A curved diffusion front has been observed. B in the center of the ridge diffuses further than at the sides. A similar effect has been observed in SUPREM-IV simulations. It is attributed to a reduction in transient enhanced diffusion close to the vertical surfaces due to recombination of ion-implantation-induced excess Si self-interstitials.