Large disparity between gallium and antimony self-diffusion in gallium antimonide

Area of Science:

• Solid-state physics
• Materials science
• Semiconductor physics

Background:

• Self-diffusion is a fundamental mass transport process in solids, crucial for understanding impurity diffusion and semiconductor device development.
• Previous self-diffusion studies in semiconductors like GaAs and GaP were limited to elements with multiple stable isotopes (e.g., Ga).
• Isotopically controlled semiconductor heterostructures have enabled precise self-diffusion studies in various materials.

Purpose of the Study:

• To investigate self-diffusion in crystalline gallium antimonide (GaSb) using an isotopically controlled multilayer structure.
• To simultaneously study the diffusion of both Gallium (Ga) and Antimony (Sb) on their respective sublattices.
• To elucidate the underlying physical mechanisms responsible for the atomic mobility differences in GaSb.

Main Methods:

• Fabrication of an isotopically controlled multilayer structure of crystalline GaSb.
• Utilizing the two stable isotopes of Ga (69Ga, 71Ga) and Sb (121Sb, 123Sb) for simultaneous diffusion studies.
• High-temperature diffusion experiments near the melting point followed by analysis of isotopic profiles.

Main Results:

• A significant difference in self-diffusion coefficients was observed between Ga and Sb in GaSb near the melting temperature.
• Gallium (Ga) atoms diffused over three orders of magnitude faster than Antimony (Sb) atoms.
• The observed diffusion behavior deviates from standard diffusion models, suggesting complex defect interactions.

Conclusions:

• The unusually slow diffusion of Sb in GaSb is attributed to reactions between point defects on the Ga and Sb sublattices.
• These defect reactions suppress the specific defects necessary for Sb self-diffusion.
• The findings necessitate advanced diffusion models to accurately describe atomic transport in compound semiconductors like GaSb.