Regensburg 2025 – wissenschaftliches Programm

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O: Fachverband Oberflächenphysik

O 70: Poster Oxides and Insulator Surfaces: Adsorption and Reaction of Small Molecules

O 70.1: Poster

Mittwoch, 19. März 2025, 18:00–20:00, P2

Nitrogen Doping of Cuprous Oxide Films: A Surface Science Perspective — Mina Soltanmohammadi and •Niklas Nilius — Carl-von-Ossietzky University, Institute of Physics, D-26111 Oldenburg, Germany

Nitrogen doping of Cu₂O films grown on Au(111) and Pt(111) supports was explored by a variety of surface-science techniques, including electron-diffraction, X-ray photoelectron-spectroscopy (XPS), scanning tunneling microscopy and photoluminescence spectroscopy (PL). The films were prepared by Cu vapor deposition and high-pressure oxidation at 50 mbar O₂. Nitrogen was inserted by adding N₂ to the reactive gas or via sputter doping. Only the latter resulted in a clear N1s signal in XPS, compatible with the insertion of N-atoms at O substitutional sites. The N-doping caused an overall degradation of the oxide lattice and suppressed the formation of the (√3×√3)R30^∘ surface reconstruction observed on pristine Cu₂O(111). Moreover, the oxide Fermi level shifted from the valence-band top into the band gap, indicative for a reduced p-type conductivity of the sample upon doping. The N-dopants featured low thermal stability and largely desorbed at  500 K, leaving behind a pronounced 850 nm PL peak due to O vacancy emission. Our findings indicate that the N-atoms initially occupy O substitutional sites but get removed easily at moderate temperature, casting doubts whether N-doping is a suitable pathway to improve the conductance and luminescence behavior of Cu₂O.

Keywords: Cuprous oxide; Doping; Nitrogen; Scanning tunneling microscopy; Photoluminescence spectroscopy