First-principles characterization of native defects and oxygen impurities in GaAs

Area of Science:

• Materials Science
• Solid State Physics
• Computational Chemistry

Background:

• Gallium arsenide (GaAs) is a critical semiconductor material.
• Understanding native defects and impurities is crucial for optimizing GaAs performance.
• The EL2 center and oxygen-related defects are known to influence GaAs electronic properties.

Purpose of the Study:

• To investigate native point defects and oxygen impurities in GaAs.
• To characterize their structural, electronic, and optical properties.
• To clarify the role of these defects as carrier traps and recombination centers.

Main Methods:

• Utilizing hybrid functional calculations for defect modeling.
• Analyzing defect transition levels and charge states.
• Comparing calculated properties with experimental observations.

Main Results:

• Dominant native defects include Ga antisites (GaAs), As antisites (AsGa), and Ga vacancies (VGa), dependent on synthesis.
• Isolated As antisites (AsGa) correspond to the experimental EL2 center but have low nonradiative electron capture.
• Oxygen impurities (OAs) and OAs-2AsGa complexes exhibit metastable states and act as effective carrier traps.

Conclusions:

• The isolated As antisite is not the main electron trap in GaAs.
• Oxygen-related defects, particularly OAs-2AsGa, are significant carrier traps and recombination centers.
• These findings have critical implications for designing GaAs-based materials with improved electronic properties.