Electronic and structural study of Cu-doped NiO from first principles and STEM/EELS

Session

Poster Session Two

Authors

Mr Galen Crumpton (1), Mr Julio de Nascimento (1), Mr Ahmad Althumali (1), Dr Adam Kerrigan (1), Dr Phil Hasnip (1), Dr Vlado Lazrov (1)

Affiliations

1. University of York

Keywords

STEM, HAADF, EELS, CASTEP, DFT, Copper, metal oxide, doped metal oxide, Nickel, Nickel Oxide, semiconductor, first principles, bandgap, vacancies, defects, formation energy, RSCAN, PBE, PBE+U, Hubbard U

Abstract text

Doping of metal oxides is a key process in the creation of materials that are at the forefront of academic research, such as nanoparticles and donor sites for perovskite materials [1, 2]. Understanding how the dopant atoms behave when incorporated into the crystalline structure is paramount to improving the efficiency of manufacturing these systems, alongside leading to improvements in their synthesis. NiO is a rather important oxide with applications that ranges from catalysis to opto-electronic and spintronic applications. The Cu doping of NiO provides a pathway to tailor the band gap and carrier concentrations, which is important for solar cell applications. For example, there has been particular interest recently in the use of Cu-doped NiO as photocathodes to significantly improve their efficiency [3]. In this work we present computational studies of NiO and Cu-doped/alloyed NiO, with the aim of correlating structural and optical properties of MBE grown films to the calculated electronic properties.

The first-principles density functional theory calculations were performed by using CASTEP [4]. A 64 atom NiO supercell was created, with the 32 Ni atoms arranged in a type-II antiferromagnetic spin arrangement.The xc-functionals RSCAN and PBE+U were both used for comparison [5, 6]. The Cu atoms were then introduced in the place of Ni, up to a maximum of 16, thus setting the doping concentration limit to 50%. Additionally, defects were added to the system to study the effect they have in the doping formation energy. The electronic properties and formation energy were calculated for each configuration and we included core EELS spectra calculations to study the hybridization of NiO with the dopants and compared with experimental results. Simulated STEM images were calculated from parameterized potentials under the multislice method as implemented in the abTEM code in order to fit the experimental STEM/HAADF data [7].

References

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