Batch-Fabricated α-Si Assisted Nanogap Tunneling Junctions

Area of Science:

• Nanotechnology
• Materials Science
• Electrical Engineering

Background:

• Development of sensitive biosensors requires precise control over nanoscale device fabrication.
• Tunneling junctions offer high sensitivity for detecting minute biological or chemical changes.

Purpose of the Study:

• To design, fabricate, and characterize highly uniform, batch-fabricated sidewall etched vertical nanogap tunneling junctions.
• To evaluate the suitability of these junctions for bio-sensing applications.

Main Methods:

• Utilized sputtered alpha-silicon (α-Si) and Atomic Layer Deposited (ALD) silicon dioxide (SiO2) as sacrificial spacer layers.
• Employed controlled dry etching to create ~10 nm air-gaps along the sidewall of the spacer.
• Fabricated nanogap electrodes with varying overlap areas and spacer gaps (~4.0 nm to ~9.0 nm).

Main Results:

• Achieved high uniformity in nanogap fabrication with average non-uniformity of 0.46 nm in SiO2 and 0.56 nm in α-Si.
• Determined the barrier potential of the spacer stack to be ~3.5 eV using tunneling measurements.
• Measured a maximum resistance of 46 × 10^3 GΩ and an average dielectric breakdown field of ~11 MV/cm.

Conclusions:

• Demonstrated a reliable method for batch fabrication of uniform vertical nanogap tunneling junctions.
• The characterized devices show promise for high-performance bio-sensing applications due to their precise nanogap control and electrical properties.