Silicon nanowires prepared by metal induced etching (MIE): good field mitters

Micro-Raman scattering and electron field emission characteristics of silicon nanowires (SiNWs) synthesized by metal induced chemical etching (MIE) are studied. Scanning electron microscopy images reveal the growth of well aligned vertical SiNWs which show red-shifted and asymmetrically broadened Raman line-shapes. The relationship between Raman shift and crystallite size, as derived from a bond-polarizability model, has been used to estimate the confinement sizes in SiNWs. The Si optical phonon peak for SiNWs showed an increase in red-shift and full width at half maxima with decreasing diameter of the SiNWs due to quantum confinement of optical phonons. The field emission characteristics of these SiNWs are studied by carrying out current-voltage measurements followed by a theoretical analysis using the 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 diameter. The reported results in the current study indicate that MIE is a simple technique to prepare well-aligned SiNWs with potentials for applications in field emission devices.