We report on the existence of two different regimes in one-step Ag-seeded InP nanowire growth. The vapor-liquid-solid-mechanism is present at larger In precursor flows and temperatures, ∼500 °C, yielding high aspect ratio and pure wurtzite InP nanowires with a semi-spherical metal particle at the thin apex. Periodic diameter oscillations can be achieved under extreme In supersaturations at this temperature range, showing the presence of a liquid catalyst. However, under lower temperatures and In precursor flows, large diameter InP nanowires with mixed wurtzite/zincblende segments are obtained, similarly to In-assisted growth. Chemical composition analysis suggest that In-rich droplet formation is catalyzed at the substrate surface via Ag nanoparticles; this process might be facilitated by the sulfur contamination detected in these nanoparticles. Furthermore, part of the original Ag nanoparticle remains solid and is embedded inside the actual catalyst, providing an in situ method to switch growth mechanisms upon changing In precursor flow. Nevertheless, our Ag-seeded InP nanowires exhibit overall optical emission spectra consistent with the observed structural properties and similar to Au-catalyzed InP nanowires. We thus show that Ag nanoparticles may be a suitable replacement for Au in InP nanowire growth.

No abstract

Fabrication methodologies for integration of nano-objects into microscale devices is still an active area of research. Here we analyze possible methods of incorporation of semiconductor nanowires into lithographically-defined electrode pads. Mechanically-transferred InP nanowires were metallized into Au and Pt pads using a electron-beam-induced Pt metallization. Atomic and Kelvin Probe Force Microscopies show that a contamination of Pt on the nanowire and the region around it can prevent application of this technique to biosensors in which surface functionalization protocols must be applied as part of the fabrication methodology. Other transfer methods with more controlled nanowire positioning, such as nanotweezers, may be necessary to overcome this problem.