A Route for Modulating the Diameter of Cylindrical Silicon Nanowires by Using Thermal Self-Ordering Silver Nanoparticles

For the synthesis of uniform sub-80-nm silicon nanowires (Si NWs), we introduce a metal-assisted chemical etching (MCE)-based facile and high-yield route, employing simple thermal annealing and vacuum deposition processes. Under rapid thermal annealing, an ultrathin silver (Ag) film on a Si substrate is self-organized into Ag nanoparticles (NPs), which are used for making Si nanoholes through a short MCE process. After sputter deposition of Au (10 nm)/Ag (20 nm) on the caved Si substrate with nanoholes, a nanomesh is obtained. Finally, with the nanomesh as an etching mask, Si NWs are successfully produced through a second MCE process. The size of the Si NWs can be modulated by controlling the thickness of the initial Ag film. The minimum diameter of the synthesized Si NWs is 30 +/- 5 nm, and the maximum diameter is 68 +/- 10 nm. Furthermore, to determine the uniformity of our Si NWs, bottom-gate field-effect transistors were fabricated and the linearity of the on-current level of these transistors with the number of addressed Si NWs was confirmed.