Si/Ge intermixing during Ge Stranski-Krastanov growth

Area of Science:

• Materials Science
• Nanotechnology
• Semiconductor Physics

Background:

• Stranski-Krastanov growth of Germanium (Ge) islands on Silicon (Si)(001) is well-documented.
• Island morphology evolution and atomic-scale structures are understood.
• Precise Ge island composition, despite known Si/Ge intermixing, remains unclear.

Purpose of the Study:

• To investigate the 3D atomic-scale composition of buried Ge dome islands on Si(001).
• To quantify the spatial distribution of Ge within the islands and wetting layer.

Main Methods:

• Atom Probe Tomography (APT) was employed for 3D atomic-scale compositional analysis.
• Analysis focused on buried dome islands formed during Stranski-Krastanov growth.

Main Results:

• Ge islands show a core-shell structure with a Ge-rich core (~55 atom % Ge).
• Ge concentration decreases radially to ~15 atom % in the surrounding region.
• Ge distribution exhibits cylindrical symmetry, with segregation limited to {113} facets.
• The wetting layer shows inhomogeneous Ge composition (5-30 atom %).

Conclusions:

• Atom probe tomography provides unprecedented 3D compositional detail of Ge islands.
• Si/Ge intermixing leads to a non-uniform Ge distribution within dome islands.
• Understanding Ge distribution is crucial for controlling properties in SiGe heterostructures.