Development of Double-Textured ZnO:B Substrates for Improving Microcrystalline Silicon Solar Cell Performance

Zinc oxide (ZnO) films are widely used as front transparent conductive oxide films in thin-film silicon solar cells. Double-textured B-doped zinc oxide (W-textured ZnO:B) substrates, which are formed by reactive ion etching (RIE) and metal-organic chemical vapor deposition, have a high haze ratio over a wide wavelength range. In this study, we have investigated the RIE conditions necessary to modify the surface morphology and the optical properties of a glass substrate. By increasing the pressure during the RIE process, the surface morphology of etched glass was changed from circular to ellipsoidal shapes, and its texture size increased. A newly developed W-textured ZnO:B substrate fabricated using the modified glass exhibited a higher haze ratio than a conventional W-textured ZnO:B substrate and achieved a higher short-circuit current in microcrystalline silicon solar cells without significant deterioration of open-circuit voltage and fill factor.