Removal of Ag remanence and improvement in structural attributes of silicon nanowires array via sintering

Abstract

Metal-assisted chemical etching (MACE) is popular due to the large-area fabrication of silicon nanowires (SiNWs) exhibiting a high aspect ratio at a low cost. The remanence of metal, i.e., silver nanoparticles (AgNPs) used in the MACE, deteriorates the device (especially solar cell) performance by acting as a defect center. The superhydrophobic behavior of nanowires (NWs) array prohibits any liquid-based solution (i.e., thorough cleaning with HNO3 solution) from removing the AgNPs. Thermal treatment of NWs is an alternative approach to reduce the Ag remanence. Sintering temperature variation is chosen between the melting temperature of bulk-Ag (962 °C) and bulk-Si (1412 °C) to reduce the Ag particles and improve the crystallinity of the NWs. The melting point of NWs decreases due to surface melting that restricts the sintering temperature to 1200 °C. The minimum sintering temperature is set to 1000 °C to eradicate the Ag remanence. The SEM–EDS analysis is carried out to quantify the reduction in Ag remanence in the sintered NWs array. The XRD analysis is performed to study the oxides (SiO and Ag2O) formed in the NWs array due to the trace oxygen level in the furnace. The TG-DSC characterization is carried out to know the critical sintering temperature at which remanence of AgNPs removes without forming any oxides. The Raman analysis is studied to determine the crystallinity, strain, and size of Si nanocrystals (SiNCs) formed on the NWs surface due to sidewalls etching. An optimized polynomial equation is derived to find the SiNCs size for various sintering temperatures.

Enhancing Si-Nanowire Solar Cell Performance through Fabrication and Annealing Optimization

“…2 (d)). With increasing annealing temperature, the SiNW length decreases due to the tip dissolution [33]. The inward pressure from the viscous dopant sol-gel is maximum at the porous SiNW tip [34]; thus, the dopant sol-gel enters the nanopores at the SiNW tips and oxidizes the inner surface.…”

“…Unwashed Ag particles from AgNO 3 during HNO 3 rinsing cause Ag remanence in SiNWs. However, the Ag trace decreases either during the PSG layer removal by HF wash or during the annealing [33]. The trapped Ag particles in the SiNW array may cause recombination due to the availability of free electrons from Ag atoms.…”

“…Raman spectra investigate the intermediate density of states (DOS) formed during the high-temperature annealing from the variation in the SiNW characteristic spectrum. The full width at half maxima (Γ) of the SiNW rst-order peak reduces up to the annealing temperature of 900°C, indicating the increasing crystallinity (Table 1) [33]. For the annealing temperature above 900°C, the Γ increases due to increased SiNW tip dissolution, leading to increased sidewall roughness [4].…”

Efficient Removal and Recovery of Ag from Wastewater Using Charged Polystyrene-Polydopamine Nanocoatings and Their Sustainable Catalytic Application in 4-Nitrophenol Reduction

“…Lately, advanced functional adsorbents have emerged as an economically feasible method, garnering substantial attention in the realm of remediating Ag-contaminated water. , Much effort has been dedicated to develop efficient and effective adsorbents with high capacity and excellent recovery performance. , In the past few decades, a wide range of adsorbents, such as mineral materials, inorganic and organic metal oxides, and polymers, have been proven to efficiently remove Ag and other heavy metals through the formation of an inner-sphere complex with targeted contaminants. − Although these adsorbents exhibit excellent capability for Ag + adsorption, challenges persist. To guarantee the recovery efficiency of Ag + , the adsorbed Ag + on the adsorbent needs to be eluted using desorption agents, such as acid, alkali, or organic solution, or the adsorbents need to be incinerated after adsorption.…”