Method of oxidation corrosion removing defect layer at the surface of silicon nanowire solar cell

Abstract

The invention relates to the technology of solar cell material and cell producing, in particular to monocrystalline silicon nanowire arrays prepared by using metal nanoparticles assisting electrodeless chemical etching method. The method firstly utilizes a first dry-oxygen oxidation process, due to low speed rate of dry-oxygen oxidation of silicon, by controlling oxidation time, an oxidation layer which is thickness-controllable is formed at the silicon nanowire, or the method utilizes hydrogen peroxide oxidation method to form an oxidation layer at the silicon nanowire; then the method utilizes HF(Hydrogen Fluoride) to corrode the silicon oxide layer at the surface of the silicon nanowire, while the silicon oxide layer is removed, the defect layer at the silicon nanowire surface is removed without damaging the shape of the silicon nanowire. The method can reduce the surface charge recombination rate and effectively improve minor carrier lifetime of the silicon nanowire, thereby the cell efficiency is improved.

Description

technical field [0001] The invention relates to solar cell materials and cell manufacturing technology, especially for single crystal silicon nanowire arrays prepared by metal nanoparticle-assisted electroless chemical etching method, using oxidation + corrosion method to remove metal-assisted chemical etching on silicon nanowires A layer of defects formed on the surface, thereby increasing the efficiency of silicon nanowire cells. Background technique [0002] As the demand for energy continues to increase, people pay more and more attention to renewable energy, especially solar energy. As an important way to utilize solar energy, photovoltaic applications have always been a research hotspot. Due to less pollution, silicon solar cells occupy a dominant position in the commercial solar cell market. At present, improving the optical properties of cells through various anti-reflection coatings and silicon surface texturing technologies is still an important way to improve the ...

AI Technical Summary

Problems solved by technology

Due to the extremely low reflectivity of silicon nanostructures, this silicon material is called black silicon; silicon nanowire solar cells based on this do not require a special anti-reflection structure. At present, the newly developed metal nanoparticle assisted Although the electroless chemical etching method can prepare silicon nanowire arrays at low cost, and the surface reflectivity of the silicon nanowire arrays can be reduced very low, the metal nanoparticle-assisted electroless chemical etching method forms many defects on the silicon surface, thereby This leads to a decrease in cell efficiency. For example, if a silicon nanowire solar cell is fabricated using conventional monocrystalline silicon cell technology (diffusion method), the conversion efficiency is only 9.31% [K. Q. Peng, Y. Xu, Y. Wu, Y. J. Yan, S. T. Lee, and J. Zhu, Aligned single-crystalline Si nanowire arrays for photovoltaic applications, Small 1(2005)pp.1062-1067], changing the direction of the nanowire array from vertical to slightly inclined, the battery conversion efficiency increased to 11.37 %【H. Fang, X. D. Li, S. Song, Y. Xu, and J. Zhu, Nanotechnology 19(2008)pp.255703】, but still far lower than the efficiency of monocrystalline silicon cells with a traditional pyramid structure, a small number of current-carrying The carrier lifetime (referred to as the minority carrier lifetime) is an important parameter of semiconductor materials. It has an important impact on the efficiency of solar cells. If the minority carrier lifetime is high, the cell efficiency will be high. The minority carrier life is related; for silicon nanowire batteries, the specific surface area is huge. If the surface defects are high, it is reflected in the high surface carrier recombination and low surface minority carrier life, so the photocurrent of the nanowire battery is small, and the battery efficiency is low. Therefore, in order to improve the efficiency of the battery, it is necessary to treat the surface defect layer of the silicon nanowire [Y. Dan, K. Seo, K. Takei, J. H. Meza, A. Javey, and K. B. Crozier, Nano Letters 11 (2011) pp. 2527 -2532], improving the minority carrier lifetime of silicon nanowires

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