Fabrication of Periodic, Flexible and Porous Silicon Microwire Arrays with Controlled Diameter and Spacing: Effects on Optical properties

TL;DR

This paper presents a wafer-scale fabrication method for creating flexible, porous silicon microwire arrays with controlled dimensions and spacing, significantly reducing reflectance and enhancing optical properties for potential applications.

Contribution

Introduces a novel wafer-scale fabrication process combining nanosphere lithography and electroless etching to control pore formation and microwire dimensions in silicon arrays.

Findings

Reflectance below 8% across 400-800 nm spectrum

Controlled pore size and microwire dimensions achieved

Mechanistic understanding of porous structure formation

Abstract

A new method of introducing nanopores with spongy morphology during fabrication of size and pitch controlled flexible silicon microwires (SiMWs) in wafer scale is presented using nanosphere lithography technique in addition to metal catalyzed electroless etching technique by varying concentration of oxidant and introducing surfactant or co-solvents to the etching solution. For achieving self-assembled monolayer closed-pack pattern of SiO2 microparticles in wafer-scale simple spin coating process was used. The effect of variation of the etchant, oxidant and surfactant on the morphology and optical properties of SiMWs were studied. By simply controlling the diameter of SiO2 microparticles and concentration of H2O2 the size of the MWs as well as the introduction of pores could be controlled in wafer-scale. Average reflectance suppressed to below 8% in the broad spectral range of 400-800 nm for these porous, spongy and flexible SiMW arrays in wafer scale. The mechanism behind this formation of spongy, porous and flexible nature of the SiMWs is also demonstrated for a better understanding of the etching process.