Influence of grain boundaries and interfaces on the electronic structure of polycrystalline CuO thin films

CuO thin films were grown by reactive magnetron sputtering and analyzed with respect to their structural, chemical, optical, and electrical properties. The films are strongly p‐type with carrier concentrations of ∼1020 cm−3. Carrier accumulation at grain boundaries is evident from temperature and ga...

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Bibliographic Details
Published in:Physica status solidi. A, Applications and materials science Applications and materials science, 2016-06, Vol.213 (6), p.1615-1624
Main Authors: Morasch, Jan, Wardenga, Hans F., Jaegermann, Wolfram, Klein, Andreas
Format: Article
Language:English
Subjects:
BOUNDARIES
Carrier density
COPPER OXIDE
CRYSTAL STRUCTURE
CuO
DENSITY
Electrical properties
electronic structure
Grain boundaries
INTERFACES
Magnetron sputtering
Open circuit voltage
polycrystalline materials
SPUTTERING
Substrates
THIN FILMS
TITANIUM DIOXIDE
Valence band
VOLTAGE
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Summary:CuO thin films were grown by reactive magnetron sputtering and analyzed with respect to their structural, chemical, optical, and electrical properties. The films are strongly p‐type with carrier concentrations of ∼1020 cm−3. Carrier accumulation at grain boundaries is evident from temperature and gas phase dependent conductivity measurements. The films show high absorption coefficients with a band gap of approximately 1.5 eV. Interface formation with TiO2 and Au was studied by photoelectron spectroscopy. Regarding the TiO2/CuO interface, a strong band bending in the TiO2 substrate and a valence band offset of ∼ 2.4 eV were observed. The TiO2 conduction band is therefore approximately midgap of CuO at the interface. CuO is chemically reduced upon Au deposition but an ideal ohmic contact is formed with a Fermi level at the valence band maximum of CuO. Solar cell device structures were prepared of fluorine‐doped SnO2/TiO2 substrates and Au back contacts, revealing open circuit voltages of
ISSN:1862-6300
1862-6319
DOI:10.1002/pssa.201533018