Fabrication of Black Silicon via Metal-Assisted Chemical Etching—A Review

Abstract

The metal-assisted chemical etching (MACE) technique is commonly employed for texturing the wafer surfaces when fabricating black silicon (BSi) solar cells and is considered to be a potential technique to improve the efficiency of traditional Si-based solar cells. This article aims to review the MACE technique along with its mechanism for Ag-, Cu- and Ni-assisted etching. Primarily, several essential aspects of the fabrication of BSi are discussed, including chemical reaction, etching direction, mass transfer, and the overall etching process of the MACE method. Thereafter, three metal catalysts (Ag, Cu, and Ni) are critically analyzed to identify their roles in producing cost-effective and sustainable BSi solar cells with higher quality and efficiency. The conducted study revealed that Ag-etched BSi wafers are more suitable for the growth of higher quality and efficiency Si solar cells compared to Cu- and Ni-etched BSi wafers. However, both Cu and Ni seem to be more cost-effective and more appropriate for the mass production of BSi solar cells than Ag-etched wafers. Meanwhile, the Ni-assisted chemical etching process takes a longer time than Cu but the Ni-etched BSi solar cells possess enhanced light absorption capacity and lower activity in terms of the dissolution and oxidation process than Cu-etched BSi solar cells.

A review of cost-effective black silicon fabrication techniques and applications

“…Cu and Ni are indeed cheaper than the other metals mentioned, and have proven to be just as effective. It is most likely that nickel is the best choice out of all the options, 61 and will become heavily used and put into effect in the solar cell manufacturing industry.…”

Direct Fabrication of Te-Doped Black Si with an Enhanced Photoelectric Performance by Femtosecond Laser Irradiation under Water

“…In addition, defect states induced by the processing may establish intermediate levels, with the possibility to indirectly narrow the band gap of intrinsic Si. Various methods have been explored to generate black Si with higher antireflection and better infrared absorption, such as reactive ion etching, 30 metal-assisted chemical etching, 31 and ultrashort pulse laser ablation. 27,32−37 Femtosecond (fs) laser processing has been demonstrated as a very attractive method to impart functionalities to the irradiated surface, also offering the possibility to process almost any material.…”

“…In addition, defect states induced by the processing may establish intermediate levels, with the possibility to indirectly narrow the band gap of intrinsic Si. Various methods have been explored to generate black Si with higher antireflection and better infrared absorption, such as reactive ion etching, metal-assisted chemical etching, and ultrashort pulse laser ablation. ,− Femtosecond (fs) laser processing has been demonstrated as a very attractive method to impart functionalities to the irradiated surface, also offering the possibility to process almost any material. In particular, several studies evidenced the enhanced photoelectric performances of the black Si elaborated by fs laser irradiation. ,,, On the one hand, the surface structures of the black Si allow light to be caught inside the textures and get multiple reflections, then suppressing surface reflection and creating more opportunities for photons to permeate into Si and thus increase the absorption.…”

Polyimide substrate textured by copper-seeding technique for enhanced light absorption in flexible black silicon

“…Black silicon (bSi) has a great potential in solar cell applications, as it provides superior broadband absorption from ultraviolet until infrared regions (Fan et al, 2021;Jia et al, The current issue and full text archive of this journal is available on Emerald Insight at: https://www.emerald.com/insight/1356-5362.htm 2017). Various methods have been used in the literature to fabricate flexible bSi wafers (with thickness of less than 100 mm), including metal-catalyzed chemical etching (MCCE), femtosecond laser irradiation and electrochemical etching (Arafat et al, 2021;Chai et al, 2020). MCCE is usually embraced, as it is simple and involves a low-cost process (Alhmoud et al, 2021).…”