Journal Article

PUBDB-2021-01471

http://join2-wiki.gsi.de/foswiki/pub/Main/Artwork/join2_logo100x88.png The role of Ga and Bi doping on the local structure of transparent zinc oxide thin films

Correia, F. C. ; Ribeiro, J. M. ; Kuzmin, A.Extern* ; Pudza, I.Extern* ; Kalinko, A.Extern*DESY* ; Welter, E.DESY* ; Mendes, A. ; Rodrigues, J. ; Ben Sedrine, N. ; Monteiro, T. ; Correia, M. R. ; Tavares, C. J. (Corresponding author)Extern*

2021
Elsevier Lausanne

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Please use a persistent id in citations: doi:10.1016/j.jallcom.2021.159489  doi:10.3204/PUBDB-2021-01471

Abstract: Transparent undoped ZnO and additionally doped with Ga and Bi thin films were produced by magnetron sputtering. The thin films were comprehensively characterized by X-ray absorption, X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), transmission and scanning transmission electron (TEM, STEM) microscopy and Raman spectroscopy. All undoped and doped films crystallise in a ZnO phase with the hexagonal wurtzite crystal structure. The local structure of the thin films was investigated by temperature-dependent X-ray absorption spectroscopy at the Zn and Ga K-edges, as well as at the Bi L$_3$-edge. It was found that the doping of Ga$^{3+}$ and Bi$^{3+}$ ions in the ZnO wurtzite structure produces distinct effects on the thin film microstructure. The substitution of Zn$^{2+}$ ions by smaller Ga$^{3+}$ ions introduces a static disorder to the thin film structure, which is evidenced by an increase in the mean-square relative displacements $σ^2$(Zn‒O) and $σ^2$(Zn‒Zn). At the same time, large Bi$^{3+}$ ions do not substitute zinc ions, but are likely located in the disordered environment at the ZnO grain boundaries. This conclusion was directly supported by energy-dispersive X-ray spectroscopy combined with TEM and STEM observations as well as by resonant and non-resonant μ-Raman experiments at room temperature, where the ZnO and ZnO:Bi spectra are similar, suggesting a lack of structural disorder in the wurtzite cell. On the other hand, the Raman disorder-activated phonon is pronounced for Ga-doping of the ZnO lattice, confirming the compositional disorder. Both XRD and XPS ruled out Ga$_2$O$_3$ phase in Ga-doped ZnO; conversely, Bi$_2$O$_3$ and a small amount of Bi‒metal phases are clearly discerned by XPS experiments, further suggesting that Bi is not incorporated in the ZnO wurtzite cell, but segregated to grain boundaries.

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Contributing Institute(s):

1. DOOR-User (DOOR ; HAS-User)
2. Experimentebetreuung PETRA III (FS-PET-S)

Research Program(s):

1. 632 - Materials – Quantum, Complex and Functional Materials (POF4-632) (POF4-632)
2. 6G3 - PETRA III (DESY) (POF4-6G3) (POF4-6G3)
3. FS-Proposal: I-20180036 EC (I-20180036-EC) (I-20180036-EC)
4. CALIPSOplus - Convenient Access to Light Sources Open to Innovation, Science and to the World (730872) (730872)

Experiment(s):

1. PETRA Beamline P65 (PETRA III)

Appears in the scientific report 2021

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Database coverage:
; ; Clarivate Analytics Master Journal List ; Current Contents - Physical, Chemical and Earth Sciences ; Ebsco Academic Search ; Essential Science Indicators ; IF < 5 ; JCR ; SCOPUS ; Science Citation Index Expanded ; Web of Science Core Collection

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