Point defect engineering strategies to retard phosphorous diffusion in germanium

Area of Science:

• Materials Science
• Solid-State Physics
• Computational Materials Science

Background:

• Phosphorous diffusion in germanium (Ge) is notably fast, posing challenges for semiconductor device fabrication and performance.
• Point defect engineering is crucial for controlling impurity diffusion and enabling technological applications.

Purpose of the Study:

• To investigate the impact of isovalent codopants, specifically tin (Sn) and hafnium (Hf), on phosphorous (P) migration in germanium.
• To explore the mechanisms of vacancy-mediated diffusion and the role of codopants in altering migration energy barriers.

Main Methods:

• Utilizing Density Functional Theory (DFT) calculations.
• Employing hybrid Density Functional calculations for enhanced accuracy.
• Simulating vacancy-mediated diffusion pathways for phosphorous in germanium.

Main Results:

• The migration energy barriers for phosphorous in germanium are significantly increased by the presence of oversized isovalent codopants like tin and hafnium.
• Oversized codopants effectively hinder the movement of phosphorous atoms through vacancy-mediated diffusion.

Conclusions:

• Tin and hafnium codoping are proposed as effective point defect engineering strategies to retard phosphorous migration in germanium.
• Hafnium codoping shows particular promise in significantly reducing phosphorous diffusion rates for advanced germanium-based technologies.