TY - GEN A1 - Meinel, Birgit A1 - Langner, Thomas A1 - Preis, Pirmin A1 - Wefringhaus, Eckard A1 - Acker, Jörg T1 - A two-step acidic texturization procedure for the manufacture of lowreflective multi-crystalline silicon solar wafer T2 - Solar Energy N2 - Texturization of multi-crystalline silicon wafers for photovoltaic application comprises the removal of the saw damage and shaping the topography of the bulk surface to create a surface with a low reflectivity, the so-called texture. Etching of multi-crystalline silicon wafers is usually carried out with acid mixtures consisting of hydrofluoric acid (HF), nitric acid (HNO₃) and hexafluorosilicic acid (H₂SiF₆). The present study reveals that such acid mixtures diluted by water or modified by the addition of ammonia solution, NH₃ (added as ammonium hydroxide solution, NH₄OH) can create textures with a significantly increased surface area exceeding that obtained by standard etching mixtures by a factor of 2.5–3. This yields a significantly reduced reflectivity of the etched wafer surface. However, the addition of water or NH₃ causes a very low etching rate, which makes such mixtures inapplicable for industrial application. To overcome this disadvantage, a two-step etching regime was developed to produce surface-enlarged solar wafers within a timespan typical for industrial production lines. This procedure comprises a first step of slow etching with a NH₃-modified etching mixture to pre-shape the ascut wafer surface. The second etching step is performed with a typical HF/HNO₃/H₂SiF₆ etching mixture that finalizes the texturization. Electrical measurements made on solar cells produced from such etched wafer confirm the improved surface quality of the two-step etched wafer compared to the reference wafer. KW - acidic texturization KW - multi-crystalline silicon KW - reflectivity KW - solar cell parameter KW - topography KW - confocal microscopy Y1 - 2019 U6 - https://doi.org/10.1016/j.solener.2019.09.051 SN - 0038-092X VL - 193 SP - 395 EP - 402 ER -