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Unusual oxidation-induced core-level shifts at the HfO2/InP interface
Jaakko Mäkelä1, Antti Lahti2, Marjukka Tuominen2
1Department of Physics and Astronomy, University of Turku, FI-20014, Turku, Finland. jaakko.m.makela@utu.fi.
Scientific Reports
|February 8, 2019
Summary
The common hypothesis that oxidation increases core electron binding energies is challenged by new findings at HfO2/InP interfaces. This study reveals no direct link between Indium core-level shifts and oxygen neighbors, impacting materials science interpretations.
Area of Science:
- Materials Science
- Surface Science
- Solid State Physics
Background:
- X-ray photoelectron spectroscopy (XPS) is crucial for analyzing elemental core-level binding energies (BE) and core-level shifts (CLS).
- Oxidation is typically assumed to increase BE due to charge transfer to electronegative oxygen.
- This assumption is widely applied in materials science and engineering.
Purpose of the Study:
- To challenge the general validity of the oxidation-induced BE shift hypothesis.
- To investigate atomic processes and core-level shifts at HfO2/InP interfaces.
- To introduce novel native oxide model interfaces for III-V semiconductors.
Main Methods:
- Ab initio calculations for theoretical modeling of HfO2/InP structures.
- Synchrotron X-ray photoelectron spectroscopy (XPS) measurements.
- Analysis of core-level shifts (CLS) and their correlation with atomic structure.
Main Results:
- Demonstrated that the intuitive hypothesis of oxidation increasing BE is not universally valid.
- Found no correlation between Indium core-level shifts (In CLSs) and the number of oxygen neighbors in HfO2/InP.
- Showed that Phosphorus CLSs can be estimated based on the number of nearby oxygen atoms.
Conclusions:
- The study highlights the necessity of complementary analyses in XPS investigations.
- Findings necessitate a re-evaluation of established models for oxidation effects in materials.
- Emphasizes the importance of understanding interface phenomena for advancing semiconductor research and development.
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