Enhancement of field emission and hydrophobic properties of silicon nanowires by chemical vapor deposited carbon nanoflakes coating

Vertically aligned silicon nanowires (SiNWs) have been synthesized by chemical etching process on commercially available p-type silicon wafer substrates. The surfaces of the as-synthesized nanowires have been modified with plasma enhanced chemical vapor deposited carbon nanoflakes. All the pure and coated SiNWs have been characterized by field emission scanning electron microscope, high resolution transmission electron microscope, Raman spectrometer and photoluminescence spectrometer. Surface wettability of the pure and carbon coated SiNWs has been studied and calculation of porosity has been done by using Cassieʹs equation. It has been found that hydrophobicity of the coated SiNWs varied with deposition time of carbon and for deposition time of 3 min the surface showed super hydrophobicity. For showing versatility of applications of the carbon coated SiNWs we have also investigated its electron field emission characteristics. Our results showed significant improvement of emission characteristics after carbon flakes with turn-on field downshifted from 9.30 to 2.77 V/μm. The results were explained due to enhanced surface roughness leading to higher enhancement factor, favorable band bending for electron emission and overall reduction of potential barrier on application of external electric field.