Textured AZO for Thin-Film Si Solar Cells: Towards Understanding the Effect of AZO Film Thickness on the Surface Texturing Properties

Abstract

Sputter-deposited Al-doped ZnO (AZO) films have been widely used as the front transparent conductive electrode for superstrate thin-film silicon (Si) solar cells. The AZO layer must be conductive enough to enable the lateral transport of electrons and sufficiently transparent to incoming light. In addition, the front AZO layer requires a rough surface texture morphology for light trapping, which improves the solar cell's current and efficiency. In this work, three types of AZO films with different layer thicknesses are prepared by pulsed DC magnetron sputtering. The post-deposition texturing is performed by using diluted hydrochloric (HCl) acid. After the HCl texturing, we find that not only the electrical performance, but also the optical scattering and morphological properties of the surface-etched AZO films can greatly depend on the initial AZO layer thickness. The AZO layer needs to be thick enough (∼700nm) in order to obtain good surface texturing properties for thin-film Si solar cell applications.