Porous Silicon Formation by Electrochemical Etching

Abstract

Porous silicon (PSi) is used as an effective material in biomedicine, sensors, solar cells, electrochemical energy, microelectronics, and nanotechnology. Considering the dependence of PSi functional properties on pore geometry and porous layer architecture, it is important to develop methods for controlled pore formation. After all, in the “procession” the method of obtaining PSi ⟶ pore geometry and architecture of PSi ⟶ functional properties of PSi, the decisive role belongs to the first participant. Among the most used methods, electrochemical etching is the most suitable for the controllability of the processes of nucleation and growth of pores since it can be controlled using the value of the current density, and the results are easily reproduced. This work analyses the literature on two types of electrochemical formation of PSi by anodic etching of (1) silicon surface and (2) silicon surface, modified with metal nanostructures. A modern explanation of the process of anodic dissolution of silicon with forming a porous surface in solutions containing HF is presented. The influence of such main factors on the process of anodic formation of PSi and its morphology is analyzed: the composition of the electrolyte and the role of each component in it; anode current density and methods of its supply (stationary, pulsed); duration; exposure to lighting; and temperature. Considerable attention is paid to the illustration of the role of alcohols and organic aprotic solvents on the formation of pore geometry. The influence of MNPs and metallic nanostructures on the process of localized metal-activated anodic etching of a semiconductor is analyzed.

Effect of Nanographene Coating on the Seebeck Coefficient of Mesoporous Silicon

“…Therefore, the appearance of these modulations can be explained by the etching cycle. Kuntyi et al [ 32 ] also underlined that the pore geometry and the architecture of the PSi vary according to several parameters, including the current regime and the total anodization time. This indicates that for a pulsed current etching regime, the duration of the imposed pulses will impact the formed porous structure.…”

Recent Advances in Applied Electrochemistry: A Review

“…It is primarily used on aluminum and its alloys to enhance surface properties and provide various benefits (durability, enhanced aesthetics since anodizing has an impact on the surface color, electrical insulation required for some applications, and improved adhesion as anodizing creates a porous surface that enhances the adhesion of paints and other coatings) [118,119] (Figure 4). Electrochemical etching or wet etching (also known as electrochemical machining) is a process that uses an electrical current and an electrolyte solution to selectively remove materials from a conductive substrate (metal or semi-conductor) to perform etching [121,122]. This can be used to create surface textures, patterns, or microstructures for various applications.…”

Effect of different etching times on the structural, morphological, electrical, and antimicrobial properties of mesoporous silicon

“…The anodization duration has a major effect on PS's morphological, optical, electrical, thermal, and structural characteristics [ 19 , 20 ]. However, increasing the etching method improves the thickness of the porous material and results in anisotropy [ 21 ]. The photosensitivity of the Schottky contact formed on PS was increased by Naderi et al, the pulsed electrochemical etching technique, that we discovered can produce uniform PS layers [ 22 ].…”