Dresden 2026 – wissenschaftliches Programm
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FM: Fachverband Funktionsmaterialien
FM 4: Focus Session: (Anti)ferroic states – Non-conventional states I
FM 4.2: Vortrag
Montag, 9. März 2026, 15:30–15:45, BEY/0138
From metal to oxide: Oxygen vacancy evolution in HfO2 controlled by PLD — •Berk Yildirim1, Oliver Rehm1, Philipp Gebauer1, Marc Neumann1, Andrei Gloskovskii3, Christoph Schlueter3, Lutz Baumgarten2, Ron Tenne4, and Martina Müller1 — 1FB Physik, U Konstanz — 2FZ Jülich — 3DESY, Hamburg — 4Technion, Haifa, Israel
Hafnium dioxide (HfO2) has emerged as a ferroelectric material for non-volatile memory applications. The ferroelectric phase is linked to the presence and amount of oxygen vacancies (OVs), but their direct experimental observation is challenging. In this work, a combination of in situ soft X-ray and ex situ hard X-ray photoelectron spectroscopy is used to trace the evolution of OVs. To systematically control the oxidation and OV concentration in HfO2, 120 nm films are grown from stoichiometric targets by pulsed laser deposition (PLD) without oxygen supply, but varying the SrTiO3 (001) substrate temperature T. With increasing T, the amount of metallic Hf is systematically reduced, while the oxide fraction increases. The evolution of Hf 4f spectral features is evaluated as the indirect signature of the T-dependent OV concentration through the Hf3+/Hf4+ spectral weight. In addition, photoluminescence measurements confirm the presence and T-dependent variation of OVs. In situ RHEED, ex situ AFM and XRD validate T-driven changes in morphology and structure, linking Hf oxidation state, vacancy concentration and film properties. These results demonstrate that T-controlled oxidation enables a systematic control of OVs and helps clarify how defects influence the formation of ferroelectric HfO2.
Keywords: HAXPES; Photoelectron Spectroscopy; HfO2; Oxygen Vacancies; PLD