electrochemical etching
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Abstract Overcoming the low fabricating efficiency of traditional chemical mechanical polishing (CMP) for Gallium nitride (GaN) is a challenge owing to its high hardness, high brittleness, and chemical inertness. Here, electrochemical etching is proposed to increase the material removal rate and acquire a high-quality surface on GaN wafers. To reveal the synergistic etching mechanism of oxidizing agent and corrosion inhibitor on the GaN wafers, electrochemical etching experiments were carried out. The optimal etching solution contained 4 wt% H2O2 and 10 mmol/L purified terephthalic acid. Experiments with various polishing parameters were comparatively investigated to verify the auxiliary effect of etching and determine the ideal parameters. Cathodoluminescence spectroscopy shows that the electrochemical etching removes the SSDs completely and the CMP process with befitting parameters does not induce supernumerary SSDs.

Abstract Fabrication of PSi is generated successfully depending upon photo-electrochemical etching process. The purpose is to differentiate the characterization of the PSi monolayer based on c-silicon solar cell compared to the bulk silicon alone. The surface of ordinary p-n solar cell has been reconstructed on the n-type region of (100) orientation with resistivity (3.2.cm) in hydrofluoric (HF) acid at a concentration of 2 ml was used to in order to enhance the conversion efficiency with 10-minute etching time and current density of 50 mA/cm2, The morphological properties (AFM) as well as the electrical properties have been investigated (J-V). The atomic force microscopy investigation reveals a rugged silicon surface with porous structure nucleating during the etching process (etching time), resulting in an expansion in depth and an average diameter of (40.1 nm). As a result, the surface roughness increases. The electrical properties of prepared PS, namely current density-voltage characteristics in the dark, reveal that porous silicon has a sponge-like structure and that the pore diameter increases with increasing etching current density and the number of shots increasing this led that the solar cell efficiency was in the range of (1-2%), resulting in improved solar cell performance.

Abstract In this work, the influence of technological parameters on the current-voltage characteristics of solar cells with porous silicon is investigated. It is shown that for photosensitive structures with a porous layer, the optimal mode is pore formation by electrochemical etching followed by diffusion. The effect of etching modes affects the character of the photosensitivity curve.

Nanostructured zinc selenide has been obtained by electrochemical etching with an H2SO4:H2O:H2O5OH=4:1:1 solution used as the electrolyte. The experiment has indicated that the surface consists of two phases, namely the upper layer made up of a dense oxide film and a low-sized porous layer underneath, with a pore diameter of (30-80) nm and a thickness of interporous walls of (15-50) nm. The investigated dependence of surface porosity on the etching time allows us to explain the main stages of the crystal’s electrochemical dissolution during anodizing. The experiment has indicated the presence of three main stages, such as the formation of the Gouy and Helmholtz layers at the semiconductor/electrolyte segregation; pore formation at defect and oxide crystallite locations; spontaneous pore formation. The PL spectra of the samples under study have demonstrated three maxima. The emission band at 2.45 eV is attributable to the presence of oxides, the band at 2.78 EV can be accounted for the corresponding excitons while the band at 2.82 eV stems from quantum-dimensional effects. Chemical analysis of the samples has also indicated the presence of oxides on the surface of the nanostructure.

Abstract Metal-assisted etching of silicon in HF aqueous solution has attracted widespread attention due to its potential applications in electronics, photonics, renewable energy, and biotechnology. In this paper, the basic process and mechanism of metal assisted electrochemical etching of silicon in vapor or liquid atmosphere based on galvanic cells are reviewed. This paper focuses on the use of gas-phase oxidants O2 and H2O2 instead of liquid phase oxidants Fe(NO3)3 and H2O2 to catalyze the etching of silicon in the vapor atmosphere of HF aqueous solution. The mechanism of substrate enhanced metal-assisted chemical etching for the preparation of large-area silicon micro nanostructure arrays is summarized, and the impact of substrate type and surface area on reactive etching is discussed.