Field emission at terahertz frequencies: AC-tunneling and ultrafast carrier dynamics

We demonstrate ultrafast terahertz (THz) field emission from a tungsten nanotip enabled by local field enhancement. Characteristic electron spectra which result from acceleration in the THz near-field are found. Employing a dual frequency pump-probe scheme, we temporally resolve different nonlinear...

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Bibliographic Details
Published in:New journal of physics 2014-12, Vol.16 (12), p.123005-9
Main Authors: Herink, G, Wimmer, L, Ropers, C
Format: Article
Language:English
Subjects:
Acceleration
Carriers
Cooling rate
Excitation
Field emission
field enhancement
Field strength
hot carrier dynamics
Hot electrons
Nanostructure
nanostructures
Nonlinear dynamics
Photoelectric emission
Photoemission
Physics
Terahertz frequencies
terahertz spectroscopy
Tungsten
ultrafast nano-optics
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Summary:We demonstrate ultrafast terahertz (THz) field emission from a tungsten nanotip enabled by local field enhancement. Characteristic electron spectra which result from acceleration in the THz near-field are found. Employing a dual frequency pump-probe scheme, we temporally resolve different nonlinear photoemission processes induced by coupling near-infrared (NIR) and THz pulses. In the order of increasing THz field strength, we observe THz streaking, THz-induced barrier reduction (Schottky effect) and THz field emission. At intense NIR-excitation, the THz field emission is used as an ultrashort, local probe of hot electron dynamics in the apex. A first application of this scheme indicates a decreased carrier cooling rate in the confined tip geometry. Summarizing the results at various excitation conditions, we present a comprehensive picture of the distinct regimes in ultrafast photoemission in the near- and far-infrared.
ISSN:1367-2630
1367-2630
DOI:10.1088/1367-2630/16/12/123005