Charge trapping in carbon nanotube loops demonstrated by electrostatic force microscopy

Area of Science:

• Materials Science
• Nanotechnology
• Surface Science

Background:

• Substrate charges significantly affect carbon nanotube (CNT) electronic devices, causing issues like hysteresis in CNT field-effect transistors.
• Understanding and controlling these substrate charges is crucial for developing stable and reliable CNT-based electronics.

Purpose of the Study:

• To quantitatively investigate substrate charges affecting single-walled carbon nanotubes (SWCNTs) on SiO2 substrates.
• To explore the role of CNTs in trapping and confining these charges.
• To demonstrate a method for manipulating and removing trapped charges.

Main Methods:

• Utilized electrostatic force microscopy (EFM) to probe and quantify charge densities on SiO2 substrates.
• Investigated SWCNTs grown via chemical vapor deposition.
• Employed scanning probe manipulation techniques to interact with and remove trapped charges.

Main Results:

• Identified charge pools with densities around 10^-8 C/cm^2 trapped within nanotube loops.
• Demonstrated that carbon nanotubes can act as effective confining barriers for substrate charges.
• Showed that trapped charges can be successfully removed using scanning probe manipulation.

Conclusions:

• Carbon nanotubes can confine substrate charges, influencing device characteristics.
• EFM provides quantitative insights into substrate charge behavior.
• Scanning probe manipulation offers a viable method for charge removal, enabling improved control over CNT device performance.