Upscaling of texture-etched zinc oxide substrates for silicon thin film solar cells

Large area (320 x 400 mm(2)) glass/ZnO-films were prepared by high-rate d.c. magnetron sputtering from ceramic targets and compared to lab-type r.f.- and m.f.-sputtered ZnO. The very uniform and initially smooth films exhibit excellent electrical and optical properties (resistivity less than or equal to 5 X 10(-4) Ohm cm, transmission > 80% for visible light and 1500-nm thick films). Upon etching in diluted hydrochloric acid they develop a surface texture. Independent of sputter technique (d.c. or r.f.) 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 pin solar cells prepared on these large area glass/ZnO samples exhibit initial efficiencies up to 9.2%, proving the viability of sputtered and texture-etched ZnO as TCO-substrate for industrial solar module production. (C) 2001 Elsevier Science B.V. All rights reserved.