An air gap moderates the performance of nanowire array transistors

Area of Science:

• Materials Science
• Nanotechnology
• Electronics

Background:

• Solution-processed nanowires offer a pathway to low-cost, flexible electronic devices.
• Stacking of nanowires during solution deposition creates an air gap between the substrate and the active material.

Purpose of the Study:

• To quantify the air gap thickness in organic semiconductor nanowire transistors.
• To investigate the impact of the air gap on transistor performance and electrical characterization.

Main Methods:

• Confocal Raman spectroscopy was employed to measure the air gap thickness.
• Electrical performance metrics, including charge carrier mobility and on-off current ratio, were analyzed.

Main Results:

• The air gap was found to be significantly larger than the nanowire diameter (at least three times).
• The air gap acts as an additional dielectric layer, reducing charge carrier accumulation.
• Ignoring the air gap leads to overestimated carrier accumulation and underestimated mobility, with corrections exceeding an order of magnitude.

Conclusions:

• Minimizing the air gap is essential for optimizing transistor performance.
• Accurate electrical characterization of stacked nanowire transistors requires accounting for the air gap.
• Findings are relevant for various one-dimensional materials, including nanowires and carbon nanotubes.