Copper Assisted Inverted Pyramids Texturization of Monocrystalline Silicon in a Nitrogen Bubbling Bath for Highly Effici
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ORIGINAL PAPER
Copper Assisted Inverted Pyramids Texturization of Monocrystalline Silicon in a Nitrogen Bubbling Bath for Highly Efficient Light Trapping Subbiramaniyan Kubendhiran 1 & Gavin Sison 1 & Hsiao Ping Hsu 1 & Chung-Wen Lan 1,2 Received: 20 April 2020 / Accepted: 11 August 2020 # Springer Nature B.V. 2020
Abstract 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(SO4)/HF/H2O2/H2O solution in a bubbling bath. The experiment was performed with different etching times, concentrations of H2O2, 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 H2O2 would be necessary for industrial production. Keywords Single crystalline . Black silicon . Inverted pyramids . Nitrogen bubbling bath . Solar cell
1 Introduction Crystalline silicon (c-Si) solar cells are currently dominant in the photovoltaic (PV) market due to their high efficiency and low cost [1, 2]. However, the large refractive index of c-Si is one of the greatest factors limiting the conversion efficiency of c-Si based solar cells [3, 4]. The fabrication of black silicon, or silicon with nano or micro structure surface textures, poses a solution to this reflectivity problem [5]. Black silicon has high light trapping capabilities and can absorb light over a wide Electronic supplementary material The online version of this article (https://doi.org/10.1007/s12633-020-00650-8) contains supplementary material, which is available to authorized users. * Chung-Wen Lan [email protected] 1
Department of Chemical Engineering, National Taiwan University, Taipei 10617, Taiwan
2
Advanced Research Center for Green Materials Science and Technology, National Taiwan University, Taipei 10617, Taiwan
range of incident angles which can therefore potentially enhance the overall efficiency of silicon solar cells [6]. However, increases to the surface area of a silicon wafer also increases undesired surface carrier recombination [7]. As a result, the efficiency of black silicon based solar cells typically does not exceed more than 10% [8]. So far, a variety
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