Synthesis and characterization of templated Si-based nanowires via vapor-liquid-solid (VLS) growth for electrical transport

Nanowire surface conduction channels have been fabricated and tested based on self-assembled Si nanowires (SiNWs) synthesized via VLS processing. Conduction channel formation utilized W and Ni silicidation. SiNWs were directly grown on silicon substrates via vapor-liquid-solid (VLS) growth process. The diameters of the SiNW templates ranged from approximately 5 to 120 nm. Nanowire synthesis via VLS growth was carried out using a SiH₄/Ar mixture at 500°C. TEM analysis confirmed crystalline VLS SiNWs. Ni evaporation and Ni and W atomic layer deposition (ALD) and post-deposition thermal processing were carried out for silicide formation. TEM-EDS results showed that ALD W was conformally deposited on the surface of SiNWs. In contrast, e-beam evaporated Ni was asymmetrically deposited on the template nanowire although the resultant silicide was nearly symmetric. Conformal Ni deposition and silicidation was successfully performed, however, using Ni ALD processing. Silicide nanowires were dispensed on Au-patterned Si wafers for electrical characterization and exhibited an improvement in electrical conductivity of eight orders of magnitude compared with that of as-grown VLS silicon nanowires.