Palladium gates for reproducible quantum dots in silicon

Area of Science:

• Quantum physics
• Materials science
• Nanotechnology

Background:

• Aluminum gates are standard for silicon quantum dot fabrication.
• Native aluminum oxide can lead to unintentional dot formation, complicating device performance.
• Shrinking gate dimensions is crucial for advancing quantum computing.

Purpose of the Study:

• To investigate palladium as an alternative gate material for silicon quantum dots.
• To develop a novel fabrication route for reproducible quantum dot formation.
• To enable electron transport measurements in the few-electron regime with reduced gate layers.

Main Methods:

• Transmission electron microscopy to study gate morphology.
• Atomic layer deposition for aluminum oxide growth.
• Fabrication of gate-defined quantum dots using palladium gates.

Main Results:

• Palladium gates avoid the formation of unintentional dots caused by native aluminum oxide.
• Reproducible fabrication of low-disorder gate-defined quantum dots was achieved.
• Shrinking gate designs with palladium allowed few-electron transport measurements using only two gate layers.

Conclusions:

• Palladium offers a promising alternative to aluminum for quantum dot fabrication.
• The novel fabrication route enhances reproducibility and device performance.
• Further research is needed to assess palladium's impact on spin qubit quality.