Dresden 2020 – scientific programme
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O: Fachverband Oberflächenphysik
O 2: Heterostructures, interfaces and surfaces (joint session HL/O)
O 2.2: Talk
Monday, March 16, 2020, 09:45–10:00, POT 151
Nanometer Scale Characterization of Al/TiOx/SiOx Electron Selective Passivating Contacts Utilizing Advanced TEM Methods — •Christoph Flathmann1, Tobias Meyer1, Valeriya Titova2, 3, Jan Schmidt2, 3, and Michael Seibt1 — 1University of Goettingen, IV. Physical Institute, Friedrich-Hund-Platz 1, 37077 Göttingen, Germany — 2Institute for Solar Energy Research Hamelin (ISFH), Emmerthal, Am Ohrberg 1, 31860, Germany — 3Institute of Solid-State Physics, Leibniz University Hannover, Hannover, Appelstraße 2, 30167, Germany
One promising possibility to further increase photovoltaic efficiency and to enable new solar cell designs is the development of carrier selective passivating contacts. A particularly interesting electron selective passivating contact consists of an n-type crystalline Si base with tunnel silicon oxide (SiOx), atomic layer deposited sub-stoichiometric titanium oxide (TiOx) and aluminum as a rear contact. It is commonly assumed that SiOx ensures high chemical interface passivation, whilst oxygen vacancies in the TiOx result in an increased open circuit voltage. However, the detailed interplay of structure, composition and electrical properties is not entirely understood yet. We, therefore, apply various STEM techniques, such as EDX, EELS and 4D-STEM, to characterize such contacts for differently treated samples. The analytical methods show strong interdiffusion at the interfaces; in particular, intermixing of Al and TiOx appears to be important for contact quality. Furthermore, the capabilities of medium resolution 4D-STEM to elucidate properties of such interfaces are explored.