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HL: Fachverband Halbleiterphysik

HL 7: Poster I

HL 7.37: Poster

Monday, March 27, 2023, 13:00–15:00, P2/EG

Combinatorial synthesis of BaZrS3 thin films: Influence of off-stoichiometry on optoelectronic and electronic properties — •Adriana Röttger, Marin Rusu, Hannes Hempel, Daniel Abou-Ras, Orestis Karalis, Ibrahim Simsek, and Thomas Unold — Helmholtz-Zentrum Berlin für Materialien und Energie, Berlin, Deutschland

The chalcogenide perovskite BaZrS3 is composed of earth-abundant elements and has potential applications for photovoltaic energy conversion. In this work, compositionally graded BaZrS3 thin films are synthesized from oxide precursors deposited by pulsed laser deposition. The compositional gradient in a range of 0.8<[Ba]/[Zr]<1.3 enables a high throughput characterization approach of structural, optical and optoelectronic properties. Sulfurization was performed in a tube furnace using H2S in Ar gas at 1000^∘C. For all the examined compositions, BaZrS3 forms as the main phase. Under Ba excess, Ruddlesden-Popper phases Ba3Zr2S7 and Ba4Zr3S10 emerge, while excess Zr forms ZrO2 on the Zr-rich side. Optical absorption spectroscopy mapping shows that the band-gap energy exhibits a minimum at 1.0 < [Ba]/[Zr] < 1.1 and ranges from 1.65 to 2.1 eV. Analysis of the optical constants n and k by ellipsometry mapping verified this trend. Low-temperature photoluminescence spectroscopy revealed deep defect states present for all compositions. Using time-resolved photoluminescence spectroscopy and optical -pump-terahertz probe spectroscopy, we found longer carrier lifetimes on the Ba-rich side, while the Zr-rich side features a higher mobility of charge carriers.