FORMATION OF ANTIREFLECTIVE SILICON SURFACES BY ELECTROCHEMICAL AND CHEMICAL METHODS
Keywords:Antireflective coating, porous silicon, solar cell, electrochemical etching, metal-assisted chemical etching.
Background. Application of the silicon-based porous textures as an efficient and commercially viable coating has to be maximally adapted to processes of the silicon solar cell manufacturing. To improve the antireflective property of Si frontal surface it is desirable to use methods allowing simultaneous changing of the value of refraction coefficient and the fabrication process parameters. Therefore, it is necessary to seek other, more perspective methods of the antireflective coating fabrication to improve the solar cell efficiency.
Objective. The aim of the paper is the fabricaion of antireflective coatings based on porous silicon by electrochemical and chemical methods for photovoltaic converters with improved parameters.
Methods. Electrochemical etching and metal-assisted chemical etching were used to form the textures on the Si wafer surface. The surface morphology of Si samples was examined using scanning electron microscopy, the elemental content was investigated using Time of Flight Secondary Ion Mass Spectrometer. The investigation of optical properties of obtained textures was performed using a Specord Plus spectrophotometer.
Results. The micro- and nanotextured Si surfaces with an average diameter 1 μm and 200 nm were obtained by electrochemical and metal-assisted chemical etching methods, respectively. In addition, the nanotextured Si samples had a lowest reflective coefficient in comparison with other textures.
Conclusions. Electrochemical and chemical methods are promising to fabricate the frontal antireflective Si surfaces of solar cells. It is possible to form electrochemically a microtextured porous Si surface with low reflectivity with a proper selected anodic charge density. The metal-assisted chemical etching method allowed forming a nanoporous surface on Si wafer with improved antireflective properties of Si surface in optical spectral range.
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