Single-fabrication-step Ge nanosphere/SiO₂/SiGe heterostructures: a key enabler for realizing Ge MOS devices

Area of Science:

• Materials Science
• Nanotechnology
• Semiconductor Physics

Background:

• Advanced semiconductor devices require precise control over material properties.
• Germanium (Ge) and silicon-germanium (SiGe) alloys are critical for next-generation electronics.
• Fabricating complex heterostructures with tunable characteristics remains a challenge.

Purpose of the Study:

• To engineer self-organized gate-stacking heterostructures using Ge-nanosphere gates and SiGe channels.
• To achieve simultaneous control over channel dimensions, gate oxide thickness, and SiGe channel properties.
• To explore the potential of these structures for fabricating germanium-based metal-oxide-semiconductor (MOS) devices.

Main Methods:

• Utilized a single oxidation step to create heterostructures by balancing oxygen, silicon (Si), and Ge interstitial concentrations.
• Employed process control to tune Ge-nanosphere diameter (5-95 nm), gate oxide thickness (2.5-4.8 nm), and SiGe channel properties.
• Achieved controlled crystal orientation, chemical composition, and strain engineering in SiGe shells.

Main Results:

• Successfully fabricated single-crystalline (100) SiGe shells with up to 85% Ge content and 3% compressive strain.
• Produced single-crystalline (110) SiGe shells with 35% Ge content and 1.5% compressive strain.
• Demonstrated high crystallinity in high-Ge-content, strained SiGe shells.

Conclusions:

• The developed method allows for precise engineering of Ge-nanosphere/SiGe-channel heterostructures.
• High-Ge-content, strained SiGe shells are suitable building blocks for Ge-based MOS devices.
• This approach offers a pathway to advanced semiconductor device fabrication.