Nanostructuring Semiconductor Surfaces Using Self-Assembled Metal Nanoparticles for Optoelectronic Applications

Abstract

Semiconductor nanostructures are key light-management elements because their geometry can strengthen light-matter interaction, suppress reflection, and enhance optical coupling. Yet their adoption across material platforms is constrained by lithography, multistep pattern transfer, persistent masks, and material-specific etching. Here, we introduce a lithography-free two-step strategy in which thermally evaporated self-assembled Ga nanoparticles act as self-consuming masks during Ar inductively coupled plasma reactive-ion etching. Correlated transmission electron microscopy on GaAs reveals the formation mechanism. Comparable erosion of the Ga nanoparticles and exposed substrate progressively converts Ga-capped pedestals into pure semiconductor nanocones while preserving crystalline order. Nanocone dimensions extend from tens to hundreds of nanometres, and surface coverage is tunable through Ga deposition and plasma power. The same process produces nanocones on GaP and Si and dense nanostructures on polycrystalline hybrid metal-halide perovskite without detectable PbI2 formation. During nanostructuring, the sun-weighted reflectance reaches minima of 11-15% on the monocrystalline substrates, whereas the perovskite achieves 0.5% after complete mask consumption. The approach therefore combines a self-assembled mask, its consumption, and pattern transfer in a single physical etching step, providing a simple route to light-coupling surfaces for III-V, Si, and perovskite optoelectronics.