Texture-etched zinc oxide substrates for silicon thin film solar cells-from laboratory size to large areas

Large area glass/ZnO-films were prepared by either dc-magnetron sputtering from ceramic targets or mf-sputtering from metallic targets and compared to small area laboratory-type rf-sputtered ZnO. The initially smooth films exhibit excellent electrical (resistivity=4-9.10 ^-4 Ωcm) and optical (average transmission >80% for visible light) properties and develop a surface texture upon etching in diluted hydrochloric acid. Independent of sputter technique (dc or rf) and substrate size, higher substrate temperatures and lower sputter gas pressures have a similar influence on the film structure and lead to more robust and etch-resistant films. Showing excellent light scattering properties, amorphous silicon p-i-n solar cells prepared on these large area glass/ZnO samples exhibit initial efficiencies up to 9.2% proving the applicability of sputtered and texture-etched ZnO as TCO-substrate for industrial solar module production