Inverted pyramid (IP) texturization on silicon wafers has recently attracted attention for the structure's light trapping ability and low specific surface area. The later property minimizes undesired carrier recombination for solar cells. Wet chemical etching methods based on alkaline and/or acidic etching have been found to be relatively cost effective for creating microscale IPs, and therefore have great potential for mass production. Metal catalytic chemical etching (MCCE) using acidic solutions is known to create these structures in the shortest timespan. In this work, we proposed a simple MCCE IP texturization method for (100) single crystalline silicon (sc-Si) using a Cu(SO 4 )/HF/H 2 O 2 /H 2 O solution in a bubbling bath. The experiment was performed with different etching times, concentrations of H 2 O 2 , and temperatures. As a unique design consideration, our process was conducted with a continuous flow of nitrogen gas bubbles to improve etching uniformity. Under optimized conditions, etching was demonstrated for full size wafers. In checking solution stability, it was found that hydrogen peroxide evaporation occurs throughout the entire process, significantly affecting etching rates and microstructure formation. Therefore, the continuous makeup of H 2 O 2 would be necessary for industrial production.

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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.