Monitoring Hydrogen Peroxide Using Electrochemically Reduced Graphene Oxide Modified Screen Printed Electrodes During Metal Assisted Chemical Etching Processes

The concentrations of etchant solution substituents in metal assisted chemical etching (MACE) processes control the morphology and reflectivity of subsequently etched wafers. In particular, the concentration of hydrogen peroxide (H2O2) plays a vital role in the MACE process. Unfortunately, the H2O2 concentration is not stable when prolonging the etching process at higher temperatures. As a result, the commercialization of MACE processes for the production of IP texturization has appeared industrially unattractive. Herein, we proposed an innovative method to monitor hydrogen peroxide during the MACE process with an electrochemical method. Reduced graphene oxide (RGO) prepared through an environmentally benign electrochemical method was used to modify a screen-printed electrode (SPE). Under an optimized condition, the RGO/SPE was used to test etching solutions. The MACE process was conducted and the hydrogen peroxide concentration within the etching solution was checked by the RGO/SPE. The RGO/SPE demonstrated excellent electrochemical performance and could record changes to H2O2 concentrations with cyclic voltammetry (CV). Interestingly, the presence of copper (Cu) in the etching solution catalyzed not only the etching process, but also the electrochemical reduction of H2O2. After etching, the reflectivity and structural morphology of the etched wafers were checked. The described modified electrode is disposable, and the fabrication process is rapid and inexpensive, allowing for real time application in, and control of, MACE processes.

Study of Anti-Glare Pattern Forming Process by Glass Etching for Improved Image Quality

In this paper, the anti-glare characteristics of strengthened glass used in the dashboard of automobiles were improved to enhanced the ability of the driver to read the display. To this end, the glass surface was etched with a solution containing HF as a main component. We adjusted the concentration of the etching solution and the etching time as variables, and the transmittance, gloss, haze value, etc. of the etched glass were measured. On the etched glass surface, an irregular pattern mainly containing dioxonium hexa-fluorosilicate crystal phases was generated, and controlling the pattern could improve the anti-glare characteristics of the glass. With higher concentration of the etching solution and longer etching time, the light transmittance, reflectance, and gloss of the etched glass were accordingly lower, while the haze value increased. We discussed the relationship between these property changes and the surface microstructure, pattern components, and roughness of the etched glass.

SUPPORTED LIQUID MEMBRANE WITH STRIP DISPERSION FOR RECOVERING INDIUM FROM ETCHING SOLUTION OF LCD INDUSTRY: INFLUENCE OF FACTORS ON PERFORMANCE

Supported liquid membrane with strip dispersion (SLMSD) is a promising process for metal recovery from e-waste or waste streams because of many advantages such as the ability to combine extraction and stripping into one single step and thus have non-equilibrium mass transfer characteristics and maximum driving force. This paper investigated the effect of important factors on SLMSD performance to recover indium from etching solution such as: pH of feed solution, extractant (Di-(2-ethylhexyl) phosphoric acid (D2EHPA)) concentration, oxalic acid concentration. It was found that 99.5 % In3+ was removed from feed solution in about 20 minutes with high concentration factor (4.5) under suitable conditions (pH 1; 0.6M Di-(2-ethylhexyl) phosphoric acid (D2EHPA), 2 wt% oxalic acid).

Porous Si (111) Fabrication Using Electrochemical Anodization: Effects of Electrode Distance and Current Density

Porous silicon (PSi) has developed for many applications such as gas and humidity sensors. Various methods are available to fabricate PSi, and electrochemical anodization is common due to low cost and easy use. Current density, etching/anodization time, type of etching solution, and electrode distance are the parameters determining resulting pores. The substrate used n-type silicon wafer with (111)-orientation and resistivity of 1.5-4.5 Ω.cm with a size of 1.5×1 cm2. The cleaning process of the samples employed the RCA cleaning procedure. Conductive contacts required for the electrochemical anodization were aluminum on the samples. The electrodes were the Si sample acting as anode and platinum (Pt) electrode as a cathode. The etching solution using a mixture of HF (40%) and ethanol (99%) with a 1:1 ratio. The electrode distance was 1.5, 2.0, and 2.5 cm. The current density for each electrode distance was 10, 30, and 50 mA/cm2 with an anodization time of 30 min. SEM and UV-Vis characterizations were applied to obtain surface morphology and reflectance, respectively. For all samples, the reflectance of PSi was lower than the reflectance of the original silicon surface (no pores). This condition indicates that the PSi is suitable as an anti-reflective layer in a solar cell. However, the PSi of reflectance curves has irregular shapes as a function of wavelength for different electrode distance and the current density. The SEM images confirmed that the pores formed on the silicon surface were inhomogeneous. The pore size decreased with the increase of the electrode distance while it increased as the increase of the current density. There was a correlation between pores size and reflectance at specific wavelength numbers.

A non-metallic additive for diamond-wire-sawn multi-crystalline silicon texturing

Diamond-wire-sawn (DWS) technology has been widely used in the photovoltaic industry. When using the HF/HNO3/H2O acid etching solution for texturing of DWS multi-crystalline silicon(mc-Si), the aid of additive is required to improve the reactivity of the mc-Si surface in the acid texturing solution. It also needs to enhance the nucleation and uniform growth of the texturing surface. This paper proposes a non-metallic additive for DWS mc-Si texturing. Sodium polyacrylate is added to the HF/HNO3/H2O acid etching solution to reduce the reflectance of DWS mc-Si and improve surface morphology. Compared to the textured wafers without additive, the surface of the wafers using this method is uniformly distributed with pits whose size is 0.5 μm×1 μm. And the weighted average reflectance of the textured wafers can be reduced from 33.32% to 23.9% in the wavelength range of 350–1100 nm, with the lowest reflectance of 19.8% reached at 950 nm. It shows a promising application prospect.

Synthesis and electrochemical properties of V2C MXene by etching in opened/closed environments

The effect of etching environment (opened or closed) on the synthesis and electrochemical properties of V2C MXene was studied. V2C MXene samples were synthesized by selectively etching of V2AlC at 90 °C in two different environments: opened environment (OE) in oil bath pans under atmosphere pressure and closed environment (CE) in hydrothermal reaction kettles under higher pressures. In OE, only NaF (sodium fluoride) + HCl (hydrochloric acid) etching solution can be used to synthesize highly pure V2C MXene. However, in CE, both LiF (lithium fluoride) + HCl and NaF+HCl etchant can be used to prepare V2C MXene. Moreover, the V2C MXene samples made in CE had higher purity and better-layered structure than those made in OE. Although the purity of V2C obtained by LiF+HCl is lower than that of V2C obtained using NaF+HCl, it shows better electrochemical performance as anodes of lithium-ion batteries (LIBs). Therefore, etching in CE is a better method for preparing highly pure V2C MXene, which provides a reference for expanding the synthesis methods of V2C with better electrochemical properties.