Electrochemical Etching of Zinc Oxide for Silicon Thin Film Solar Cell Applications

A novel approach is presented for introducing a surface morphology with beneficial light scattering properties to sputter-deposited ZnO:Al films, which are used as front contact in Si thin film photovoltaic devices. Electrochemical anodization was used to trigger local dissolution, leading to interfacial structures complementary to those commonly prepared by an etching step in diluted HCl. By systematic variation of electrochemical etching conditions and electrolytes, the essential experimental parameters for designing the ZnO film surface were evaluated. The prepared films were characterized by scanning electron microscopy, four-point resistance and Hall measurements. Furthermore, electrochemical and chemical etching steps were combined to generate a diversity of different surface morphologies. The application of such films in microcrystalline Si single junction solar cells has shown promising initial results. (C) 2011 The Electrochemical Society. [DOI: 10.1149/1.3583636] All rights reserved.