Abstract
Besides surface passivation, a low contact resistivity is one of the most important requirements of passivating contacts in order to achieve good carrier selectivity. In this work, different methods to determine the contact resistivity were performed and compared using a passivating contact structure consisting of poly silicon on a thin silicon oxide. As the traditional 1D Transmission Line Model (TLM) includes many assumptions that are not valid for complicated structures and even the application of the analytical 2D TLM is limited, especially for very low contact resistivity values, 3D numerical simulations with Quokka3 were carried out to accurately model passivating contact structures and determine the contact resistivity by comparison to electrical measurements. The investigated sample showed both, good passivation quality with implied open-circuit voltage iVoc of 716 mV together with a low specific contact resistivity of 0.21 mΩ·cm2 as extracted from the numerical simulations. Using our method, it is possible to distinguish the sources of the contact resistivity. A fraction of 0.11 mΩ·cm2 could be attributed to the interface between metal & poly-Si layer and 0.10 mΩ·cm2 results from the interface between poly-Si layer & bulk.