  Micro-Raman scattering and electron field emission characteristics of silicon
nanowires (SiNWs) synthesized by metal assisted chemical etching (MACE) are
investigated. Scanning electron microscopy images reveal the growth of well
aligned vertical SiNWs. Raman shift and size relation from bond-polarizability
model has been used to calculate exact confinement sizes in SiNWs. The Si
optical phonon peak for SiNWs showed a downshift and an asymmetric broadening
with decreasing diameter of the SiNWs due to quantum confinement of optical
phonons. The field emission characteristics of these SiNWs are studied based by
carrying out current-voltage measurements followed by a theoretical analysis
using Fowler-Nordheim equation. The electron field emission increased with
decreasing diameter of SiNWs. Field emission from these SiNWs exhibits
significant enhancement in turn-on field and total emission current with
decreasing nanowire size. The reported results in the current study indicate
that MACE is a simple technique to prepare well-aligned SiNWs with potentials
for applications in field emission devices.
