Diameter modification of silicon nanowires by ambient gas

Si nanowires (SINWs) with different diameters have been synthesized by laser ablation in different ambient gases. SINWs with the diameter distribution peaks at $\text{∼13.2}$ and $\text{∼9.5}$ nm have been obtained respectively in He and Ar (5% ${\mathrm{H}}_2\mathrm{).}$ SINWs produced in ${\mathrm{N}}_2$ had the smallest peak diameter at 6 nm, and are mixed in with some spherical particles with diameters ranging from $\text{∼9}$ nm to several hundreds nm. Elements from the ambient gas were not detected in the SINWs. SINWs produced in Ar(5% ${\mathrm{H}}_2)$ and ${\mathrm{N}}_2$ atmospheres exhibited photoluminescence and spectral blue-shift with diameter reduction, which are attributable to two-dimensional quantum confinement effects in crystalline nanowires.