Foldyna Martin, Moreno Mario, Roca i Cabarrocas Pere, De Martino Antonello
Laboratoire de Physique des Interfaces et des Couches Minces, CNRS, Ecole Polytechnique, 91128 Palaiseau, France.
Appl Opt. 2010 Jan 20;49(3):505-12. doi: 10.1364/AO.49.000505.
Dry plasma etching is a promising technique for crystalline silicon surface texturing aimed at improving solar cell efficiencies by reducing incident light reflection and backscattering at the cell front surface. In this work we present a new optical characterization technique for textured surfaces based on a Mueller polarimeter coupled with a high numerical aperture microscope operated either in real or in angular spaces. This tool provides both the specularly reflected and the angle-resolved backscattered intensities in a very efficient manner, due to the absence of moving parts. Three different silicon samples were etched in a standard reactor with SF(6)/O(2) plasmas at various RF powers, resulting in different textures that were characterized by scanning electron microscopy, standard reflectometry, and by our tool. The three techniques yielded consistent results. However, reflectometry could not take into account the backscattered light from highly textured surfaces, leading to significant underestimation of the overall amount of the reflected light. In contrast, our tool has demonstrated the potential to measure both reflected and backscattered light quickly and efficiently for all samples, paving the way for a new characterization technique for textured solar cells both at the development and at the production stage.
干法等离子体刻蚀是一种很有前景的用于晶体硅表面纹理化的技术，旨在通过减少电池前表面的入射光反射和背散射来提高太阳能电池效率。在这项工作中，我们提出了一种基于穆勒偏振仪与高数值孔径显微镜相结合的新型光学表征技术，该显微镜可在实空间或角空间中运行。由于没有运动部件，该工具能够以非常高效的方式提供镜面反射强度和角分辨背散射强度。在标准反应釜中，用SF(6)/O(2)等离子体在不同射频功率下对三种不同的硅样品进行刻蚀，从而产生不同的纹理，并用扫描电子显微镜、标准反射测量法以及我们的工具对其进行表征。这三种技术得出了一致的结果。然而，反射测量法无法考虑来自高度纹理化表面的背散射光，导致对反射光总量的显著低估。相比之下，我们的工具已证明有潜力快速、高效地测量所有样品的反射光和背散射光，为在开发和生产阶段对纹理化太阳能电池进行新的表征技术铺平了道路。
