Regensburg 2025 – scientific programme
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DS: Fachverband Dünne Schichten
DS 13: Poster
DS 13.48: Poster
Thursday, March 20, 2025, 18:00–20:00, P1
In and ex situ detection of oxygen vacancies in HfO2 - advanced by PLD growth control and (HAX)PES spectroscopy — •Berk Yildirim1, Seema Seema1, Oliver Rehm1, Pia Düring1, Andreas Fuhrberg1, Andrei Gloskovskii2, Christoph Schlueter2, and Martina Müller1 — 1Fachbereich Physik, Universität Konstanz, 78457 Konstanz, Germany — 2DESY, Hamburg, Germany
Hafnium dioxide (HfO2) has emerged as a promising ferroelectric material, particularly suitable for non-volatile memory devices. Ferroelectricity in HfO2 is closely linked to oxygen vacancies (OV), but their direct experimental observation is challenging. This study uses tailored growth conditions to systematically control the OV concentration in HfO2 thin films as an essential prerequisite for their in and ex situ detection. In our pulsed laser deposition (PLD) system, parameters such as temperature, laser fluence, and oxygen partial pressure were varied to prepare HfO2 thin films with defined OV concentrations. In situ X-ray photoelectron spectroscopy (XPS) and ex situ hard X-ray photoelectron spectroscopy (HAXPES) provided detailed insight into OV distribution with different depths sensitivity, while structural properties were examined by in situ RHEED and ex situ X-ray diffraction (XRD) as well as atomic force microscopy (AFM). In and ex situ (HAX)PES analysis indicates a direct relationship between oxygen supply and the OV content via analysis of the Hf3+/Hf4+ spectral weight. In addition, the structural analysis points towards a systematic dependence between the onset of epitaxy and oxygen supply.
Keywords: HAXPES; Photoelectron Spectroscopy; HfO2; Oxygen Vacancies; PLD