Tackling Disorder in γ-Ga2 O3
Laura E Ratcliff1,2, Takayoshi Oshima3, Felix Nippert4
1Department of Materials, Imperial College London, London, SW7 2AZ, UK.
Advanced Materials (Deerfield Beach, Fla.)
|July 22, 2022
Summary
Gallium oxide (Ga2 O3) research is advancing with a new atomistic model for the disordered γ-phase. This model aids in understanding and engineering the electronic structure of Gallium oxide for power electronics.
Area of Science:
- Materials Science
- Solid State Physics
- Computational Materials Science
Background:
- Gallium oxide (Ga2 O3) and its polymorphs are gaining attention for electronic applications.
- The polymorphic nature of Ga2 O3 offers opportunities for electronic structure engineering, particularly for power electronics.
- The γ-Ga2 O3 phase presents significant challenges in synthesis, characterization, and theoretical modeling due to its disorder and complex structure-electronic relationships.
Purpose of the Study:
- To develop a robust atomistic model for the disordered γ-Ga2 O3 phase.
- To investigate the structure-electronic-structure relationship in γ-Ga2 O3.
- To provide a framework for understanding and engineering the electronic properties of complex, disordered oxides.
Main Methods:
- Utilized density functional theory (DFT) combined with a machine-learning approach.
- Screened approximately one million potential structures to develop the atomistic model.
- Employed surface and bulk sensitive soft and hard X-ray photoelectron spectroscopy, X-ray absorption spectroscopy, spectroscopic ellipsometry, and photoluminescence excitation spectroscopy for experimental validation.
Main Results:
- Developed a robust atomistic model for the γ-Ga2 O3 phase.
- Experimental results from various spectroscopy techniques were compared with theoretical predictions.
- The onset of strong absorption was determined to be 5.1 eV at room temperature (spectroscopic ellipsometry), aligning with photoluminescence excitation spectroscopy results (5.17 eV at room temperature, shifting to 5.33 eV at 5 K).
Conclusions:
- The study presents a significant advancement in modeling complex, disordered oxide systems like γ-Ga2 O3.
- The developed model is crucial for understanding how local coordination and overall structure influence the electronic structure of Ga2 O3.
- This work paves the way for targeted electronic structure engineering in polymorphic oxide systems for advanced applications.
