Formation of Hierarchical Pyramid-structured Si with Nanoholes by Using Thermally Dewetted Ag Thin Films

Abstract

Si surface texturing generally requires an etching process to improve the anti-reflection and the self-cleaning properties of the surface. Among the various etching techniques for surface texturing, the wet etching method has been widely adopted as a relatively simple and inexpensive manufacturing method. In this study, we report the effects of hierarchical pyramid-structured Si with nanoholes formed using a chemical wet etching process with thermally dewetted Ag thin films. First, alkaline etching was performed on a Si wafer to fabricate micrometer-sized random pyramid structures. Then, Ag thin film was thermally grown on the pyramid-structured Si. Finally, nanopores were formed on the random pyramid structure via metal-assisted chemical etching. The final morphology of Si was a hierarchical random pyramid structure with nanoholes, exhibiting both anti-reflection and superhydrophobicity. The average reflectance decreased to ∼4%, and the contact angle increased to 170.5°, allowing these surfaces to be used in various wettability-controlled optoelectronic devices, such as Si solar cells for where light trapping and self-cleaning are essential.