Millimeter-long carbon nanotubes: outstanding electron-emitting sources

Area of Science:

• Materials Science
• Condensed Matter Physics
• Nanotechnology

Background:

• Electron sources are crucial components in various electronic devices.
• Carbon nanotubes (CNTs) possess unique electronic properties suitable for electron emission applications.
• Achieving stable and efficient electron emission at low electric fields remains a key challenge.

Purpose of the Study:

• To fabricate and characterize highly efficient electron sources using millimeter-long, crystalline carbon nanotubes.
• To investigate the electron emission properties, including turn-on field, threshold field, and current density.
• To explore the potential of these CNT electron sources for applications such as cathodoluminescence.

Main Methods:

• Fabrication of millimeter-long, highly crystalline carbon nanotube structures.
• Measurement of electron emission characteristics under varying electric fields.
• Demonstration of intense electron beam generation via cathodoluminescence.
• Density functional theory (DFT) calculations to model field emission properties.

Main Results:

• Electron emission initiated at electric fields as low as 0.17 V/μm.
• Threshold emission achieved at 0.24 V/μm.
• High peak current density of 750 mA cm⁻² obtained at 0.45 V/μm.
• Demonstrated visible light production through cathodoluminescence.
• DFT calculations revealed a correlation between CNT length and field enhancement factor.

Conclusions:

• Millimeter-long, highly crystalline carbon nanotubes represent a highly efficient electron source.
• The developed CNT electron sources exhibit excellent stability and high current density at low electric fields.
• These findings suggest significant potential for advanced applications requiring intense electron beams.