Vacancy Defects in Ga₂O₃: First-Principles Calculations of Electronic Structure

Area of Science:

• Materials Science
• Condensed Matter Physics
• Computational Materials Science

Background:

• Gallium Oxide (Ga2O3) is a promising wide-bandgap semiconductor with potential applications in electronics.
• Understanding point defects, such as oxygen and gallium vacancies, is crucial for controlling the electrical properties of Ga2O3.
• The origin of intrinsic conductivity in Ga2O3 remains a subject of research.

Purpose of the Study:

• To investigate the electronic structure and defect properties of oxygen and gallium vacancies in monoclinic beta-Gallium Oxide (β-Ga2O3).
• To determine the role of these vacancies in the n-type and p-type conductivity of β-Ga2O3.
• To provide theoretical insights into defect behavior for material optimization.

Main Methods:

• Employed first-principles density functional theory (DFT) calculations.
• Utilized the hybrid exchange-correlation functional B3LYP.
• Applied the supercell approach to simulate isolated point defects in β-Ga2O3.

Main Results:

• Oxygen vacancies in β-Ga2O3 were identified as deep donor defects, incapable of effectively contributing to n-type conductivity.
• Gallium vacancies in all charge states were found to be deep acceptor defects.
• The transition levels of gallium vacancies are located more than 1.5 eV above the valence band maximum.
• Gallium vacancies exhibit high formation energies (>10 eV), precluding their role in p-type conductivity.

Conclusions:

• Neither oxygen nor gallium vacancies are responsible for the intrinsic n-type or p-type conductivity in β-Ga2O3.
• The findings suggest that other intrinsic or extrinsic defects likely govern the electrical behavior of β-Ga2O3.
• This study provides a fundamental understanding of point defect physics in β-Ga2O3, guiding future experimental research.