Temperature Etching and Metallic Agent Concentration Effect on Structure, Morphology and Wettability of Silicon Nanowires

Abstract. Structural, Morphologycal and Wettability of SiliconNanowires (SiNWs) elaborated using Ag assisted electroless chemical etching are investigated. Prior the etching, Ag nanoparticles (AgNPs) were deposited at room temperature in a HF/AgNO3 solution with different concentration of AgNO3. The XRD spectra of the Ag NPs deposit show a good crystallinity. The effects of temperature etching bath and concentrations of AgNO3 on the etching process were examined. The morphological study, performed using a Scanning Electron Microscopy (SEM), shows porous silicon layer of 2µm for the lower temperature etching. For 25°C, perpendicular silicon nanowires about 15µm were formed. For the higher etching temperature (50°C), the silicon nanowire about 50 nm in diameter and 50µm in length were formed. The impact of Ag concentration on the SiNWs formation is examined in the second part of the present work. It is shown that the etching depth decreases as the Ag concentration decreases with values of 2.8 μm and 2 μm for concentrations of 0.025M and 0.0125M, respectively. The hydrophobicity of the samples was monitored by measuring the contact angle between a drop of water and the sample surface. It was established that the morphology is strongly influenced by etching conditions and their wettability changes from superhydrophilic to hydrophobic. FTIR analysis confirms the oxide-free silicon nanowires.