Si substrate controlled in-plane synthesis of self-assembled nanostructures catalyzed by Au nanoparticles

Self-assembled in-plane fabrication of Cu₃Si and Mg₂SiO₄ nanostructures were achieved on Si substrates by a simple vapor transport method. The morphologies of the as fabricated structures were controlled by the surface orientation of the substrates, i.e. Cu₃Si nanowires (NWs), nanosquares (NSs), and nanotriangles (NTs) were synthesized on Si (110), (100), and (111) substrates, respectively. In the case of Mg₂SiO₄, NWs with specific growth directions were observed. All the sides of the NTs & NSs and the growth directions of the NWs are along Si <110>, indicating that the symmetries of nanostructure growth break into 2, 4, and 6 folds on Si (110), (100), and (111). Au nanoparticles (NPs) were used as the catalyst and played critical roles by absorbing metal vapor and breaking the barrier of native oxide layer on Si substrates. The positions of the as fabricated nanostructures were controlled by the Au NPs and the growth of Mg₂SiO₄ NWs can work as a mechanism for transporting Au NPs along specific directions.