Abstract
Taper- and rodlike Si nanowires (SiNWs) are synthesized successfully on Si and Si 0.8 Ge 0.2 substrates. The growth mechanisms of taper- and rodlike SiNWs are proposed to be oxide-assisted growth (OAG) and vapor-liquid-solid (VLS) growth, respectively. For taperlike SiNWs annealed at 1200 °C for 3 h, the emission peaks are found at 772, 478, and 413 nm. On the other hand, for rodlike SiNWs annealed at 1200 °C for 4 h, emission peaks are found at 783, 516, and 413 nm. From the field-emission measurements, the taperlike Si nanowires exhibit superior field-emission behavior with a turn-on field of 6.3-7.3 V/μm. The field enhancement, β, has been estimated to be 700 and 1000 at low and high fields, respectively. The excellent field-emission characteristics are attributed to the perfect crystalline structure and the taperlike geometry of the Si nanowires. © 2005 American Chemical Society.