Density functional tight binding study of β-Ga₂O₃: Electronic structure, surface energy, and native point defects

Area of Science:

• Materials Science
• Computational Chemistry
• Solid State Physics

Background:

• Monoclinic gallium oxide (β-Ga₂O₃) is a promising semiconductor material.
• Accurate modeling of β-Ga₂O₃ properties is crucial for its technological applications.
• Existing computational methods may be limited in scale for complex simulations.

Purpose of the Study:

• To develop a new parameter set for the Density Functional Tight Binding (DFTB) method specifically for β-Ga₂O₃.
• To validate this parameter set by comparing DFTB calculations with advanced Density Functional Theory (DFT) results.
• To enable efficient, large-scale quantum chemical calculations for β-Ga₂O₃.

Main Methods:

• Development of a novel parameter set for DFTB modeling of β-Ga₂O₃.
• Performing DFTB calculations for bulk electronic band structure.
• Calculating surface energies of low-index surfaces and formation energies of native point vacancy defects.
• Comparing DFTB results with state-of-the-art DFT calculations.

Main Results:

• The developed DFTB parameter set accurately predicts the bandgap energy of β-Ga₂O₃ (4.87 eV).
• Calculated surface energies show the correct stability order for low-index surfaces, agreeing semi-quantitatively with experimental data.
• Formation energies and transition levels of oxygen and gallium vacancies are in good agreement with previous DFT studies.

Conclusions:

• The new semiempirical DFTB parameter set for β-Ga₂O₃ is validated for bulk, surface, and point defect properties.
• This parameter set offers a computationally efficient approach for large-scale quantum chemical simulations of β-Ga₂O₃.
• The developed model will be valuable for advancing research and development in β-Ga₂O₃ based technologies.