Laser-assisted APT investigation of gold atoms in SiNWs. (a) SEM image of an individual SiNW. The gold droplet is clearly detected at the top end of SiNW. (b) A slice of the 3 D reconstruction volume of one part of SiNW characterized by the laser-assisted APT. Each dot represents one atom in the reconstruction volume. Si and Au atoms are represented by red and yellow dots, respectively. The slice surface is 32 × 130 nm2. (c,d) Mass spectra of two regions in SiNW: top end and interior (the dashed box in b) of SiNW. The Au+ peak can be clearly detected in mass spectrum at the top end region of SiNW.
Roussel et al. Nanoscale Research Letters 2011 6:271 doi:10.1186/1556-276X-6-271