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High-density Au nanorod optical field-emitter arrays.
R G Hobbs1, Y Yang, P D Keathley
1Research Laboratory of Electronics, Massachusetts Institute of Technology, Cambridge, MA, USA.
Nanotechnology
|October 31, 2014
Summary
High-density gold nanorod arrays generate electrons via multiphoton absorption. Researchers investigated emission mechanisms and observed laser-induced damage in these novel electron emitters.
Area of Science:
- Plasmonics
- Nanophotonics
- Electron Emission
Background:
- Electron emitters are crucial for various applications, including microscopy and particle accelerators.
- Nanostructured materials offer unique optical and electronic properties for enhanced electron emission.
- Ultrafast laser excitation provides a pathway for novel electron emission mechanisms.
Purpose of the Study:
- To design, fabricate, and characterize high-density arrays of gold (Au) nanorod electron emitters.
- To investigate the electron emission mechanisms under ultrafast femtosecond near-infrared radiation excitation.
- To explore the behavior at low and high laser fluences, including space-charge effects and optical field emission.
Main Methods:
- Fabrication of Au nanorod arrays using high-resolution electron beam lithography.
- Excitation of nanorods using ultrafast femtosecond near-infrared radiation.
- Characterization of electron emission using power-law scaling, investigation of space-charge-limited current, and electron time-of-flight spectroscopy.
Main Results:
- Observed electron emission characteristic of multiphoton absorption at low laser fluence, evidenced by power-law scaling.
- Investigated the onset of space-charge-limited current and strong optical field emission at high laser fluence.
- Observed laser-induced structural damage at applied optical fields above 5 GV m(-1) and measured emitted electron energy spectra.
Conclusions:
- Demonstrated the feasibility of high-density Au nanorod arrays as efficient electron emitters.
- Elucidated the distinct electron emission mechanisms at varying laser fluences.
- Identified operational limits related to laser-induced damage, providing insights for device optimization.
