Wet chemical etching with dry metal deposition method has been developed to fabricate large-area aligned silicon nanowire (SiNW) arrays. The combination of nanoclusters Ag film with proper interconnection and interspaces (of about 20 nm thick), and proper temperature during etching (from 20 to 80 °C) is vital to successfully fabricating large-area uniform SiNW arrays. Raman and photoluminescence spectra of the SiNW arrays indicated their potential applications in chemical detection and optical devices ,respectively.
One-step metal-assisted electroless chemical etching of p-type silicon substrate in NH4HF2/AgNO3 solution was investigated. The effect of different etching parameters including etching time, temperature, AgNO3 concentration and NH4HF2 concentration were investigated. The etched layers formed were investigated by scanning electron microscopy (SEM) and Photoluminescence. It was found that the etched layer was formed by well-aligned silicon nanowires. It is noted that their density and length strongly depend on etching parameters. Room temperature photoluminescence (PL) from etched layer was observed. It was observed that PL peak intensity increases significantly with AgNO3 concentration.
Nanostructured solar cells with coaxial p-n junction structures have strong potential to enhance the performances of the silicon-based solar cells. This study demonstrates a radial junction silicon nanowire (RJSNW) solar cell that was fabricated simply and at low cost using wet chemical etching. Experimental results reveal that the reflectance of the silicon nanowires (SNWs) declines as their length increases. The excellent light trapping was mainly associated with high aspect ratio of the SNW arrays. A conversion efficiency of ∼7.1% and an external quantum efficiency of ∼64.6% at 700 nm were demonstrated. Control of etching time and diffusion conditions holds great promise for the development of future RJSNW solar cells. Improving the electrode/RJSNW contact will promote the collection of carries in coaxial core-shell SNW array solar cells.
Nanowires: Decoupling Diameter and Pitch in Silicon Nanowire Arrays Made by Metal-Assisted Chemical Etching (Adv. Funct. Mater. 1/2014)