Nano-Chemical and Contact Resistivity Characterization of Parasitic Oxides at Metal/TCO Interfaces

Electrical transport losses at semiconductor interfaces play a crucial role in the performance of next generation tandem solar cells or hybrid solar cells for photo-electrochemical applications. Key material parameters are the interfacial composition and electronic states on the nanoscale. In this contribution, we investigate sputtered Al/ZnO:Al layer stacks as model system for interfacial oxide formation under different O2/Ar partial pressure ratios and temperature treatments. X-ray photoelectron spectroscopy (XPS) and energy-dispersive X-ray spectroscopy (EDX) in a transmission electron microscope (TEM) are used to characterize the interfacial structure and composition on atomic dimensions. Micro transfer length measurements (μTLM) are performed to evaluate the local electrical transport properties with enhanced sensitivity. The application of the presented characterization workflow on contact structures in complex multi-layer systems, e.g. perovskite silicon tandem solar cells, is discussed. © 2021 IEEE.