Superhydrophobic and Low Light Reflectivity Silicon Surfaces Fabricated by Hierarchical Etching

Abstract

Silicon is employed in a variety of electronic and optical devices such as integrated circuits, photovoltaics, sensors, and detectors. In this paper, Au-assisted etching of silicon has been used to prepare superhydrophobic surfaces that may add unique properties to such devices. Surfaces were characterized by contact angle and contact angle hysteresis. Superhydrophobic surfaces with reduced hysteresis were prepared by Au-assisted etching of pyramid-structured silicon surfaces to generate hierarchical surfaces. Consideration of the Laplace pressure on hydrophobized hierarchical surfaces gives insight into the manner by which contact is established at the liquid/composite surface interface. Light reflectivity from the etched surfaces was also investigated to assess application of these structures to photovoltaic devices.

The superhydrophobicity of polymer surfaces: Recent developments

“…Initially coatings suggested for this purpose were predominantly inorganic with a hydrophobic surface, 65 but recently some organic suggestions have been put forward, partly due to current research into polymeric solar cells. These include layer by layer materials 66 and PDMS microstructures.…”

3D Out‐of‐Plane Rotational Etching with Pinned Catalysts in Metal‐Assisted Chemical Etching of Silicon

“…[9][10][11][12][13] MACE is an electroless chemical-etching technique that can etch sub-micro-and nanofeatures in silicon with high aspect ratios and it has been widely used to fabricate photoluminescent silicon, [ 14 , 15 ] Si nanowires, [ 9 , 16 ] and superhydrophobic structures. [ 17 ] MACE uses noble metal nanoparticles, discontinuous thin fi lms, [ 9 , 16 , 18 ] or, more recently, patterned catalysts [ 13 ] to locally increase the silicon dissolution rate in a solution of hydrofl uoric acid (HF) and an oxidizing agent such as hydrogen peroxide (H 2 O 2 ) to create a localized galvanic cell across the catalyst particle to both reduce the H 2 O 2 and oxidize the silicon. It is proposed that the etching process begins as the H 2 O 2 is catalytically reduced by the metal catalyst, which creates a local cathode that injects holes (h + ) into the valence band of the Si, leading to an h + -rich region of silicon (Si * ) surrounding the metal catalyst.…”

Evolution of Etching Kinetics and Directional Transition of Nanowires Formed on Pyramidal Microtextures

“…Generally, a two-step MACE process [24][25][26][27] [24,25] light-trapping, [26,27] and bio-sensing [28] capabilities. To reduce fabrication complexity further, nanotextures with controlled orientations should be formed through a single-step MACE [12][13][14] on microtextures, but this technique has not been reported yet.…”