Berlin 2018 – scientific programme

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O: Fachverband Oberflächenphysik

O 44: Poster: Oxide and Insulator surfaces: Structure, Epitaxy, Growth and Adsorption

O 44.6: Poster

Tuesday, March 13, 2018, 18:15–20:30, Poster A

Surface terminations of oxidized Nb(110), from Nb₂O₅ to NbO_{1 ≈ x} — •Kuanysh Zhussupbekov¹, Brian Walls¹, Killian Walshe¹, Emma Norton¹, Sergey I. Bozhko², Karsten Fleischer¹, Andrey M. Ionov², Valery N. Semenov², and Igor V. Shvets¹ — ¹School of Physics and Centre for Research on Adaptive Nanostructures and Nanodevices (CRANN), Trinity College, University of Dublin, Dublin 2, Ireland — ²Institute of Solid State Physics, Russian Academy of Sciences, Chernogolovka, Russia

The oxidation of single crystalline Nb(110) is investigated by low-energy electron diffraction (LEED), X-ray photoelectron spectroscopy (XPS), scanning tunneling microscopy (STM) and spectroscopy (STS). Oxidizing at low temperature and/or high oxygen partial pressure results in the formation of Nb₂O₅. STM measurements reveal an amorphous surface which is found to be insulating by STS measurements. Annealing in ultra-high vacuum (UHV) above 700^oC removes this native oxide and sees the formation of NbO_{x ≈ 1} surface [1]. This surface is characterized by stick-shaped NbO_{x ≈ 1} nanocrystals. The terrace step width is defined by the nanocrystal stick length and one-dimensional terrace states are observed by STS measurements. Ion bombardment of this surface and subsequent annealing forms a NbO_{x ≈ 1} surface with a different terrace structure. Finally, the oxidation of the NbO_{x ≈ 1} nanocrystal surface is investigated; room temperature oxidization and subsequent UHV annealing results the extra oxygen sitting in between the NbO_{x ≈ 1} nanocrystals.

[1]. I. Arfaoui et al., Physical Review B 65, 115413 (2002).