Metal-Assisted Silicon Chemical Etching Using Self-Assembled Sacrificial Nickel Nanoparticles Template for Antireflection Layers in Photovoltaic and Light-Trapping Devices

Thin film dewetting is a simple patterning approach that provides a straightforward method for fabricating silicon structures using metal-assisted chemical etching (MacEtch). Currently, this has been mainly demonstrated with a gold (Au) or silver (Ag) catalyst for MacEtch, and to accomplish this, an extra Au or Ag nanoparticles lift-off step is required. The uncertain success with the lift-off process is potentially a major hindrance to achieve low-cost, large-scale, and uniform Si nanostructures. In this work, we report on the use of nickel (Ni) as an alternative sacrificial metal for the dewetting process. The dewetting phenomenon of Ni on silicon dioxide is investigated to show that controllable sizes and density are achievable for this material system. A physical model to describe the relationship among Ni film thickness, particle interspacing, and density is proposed. Using the Ni nanoparticles as a starting mask template, we demonstrate an improved approach for the large-scale fabrication of silicon nanowires without the use of lithography methods. This not only eliminates problems associated with lift-off but also allows for scaling up of such fabrication by using the proposed self-assembly approach, which holds great potential in furthering the versatility of the MacEtch technique in antireflection surfaces and light-trapping device applications.