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Proceedings Paper

Demonstration of high-spatial resolution in ultrafast scanning tunneling microscopy
Author(s): Dzmitry A. Yarotski; Giovanni P. Donati; Antoinette J. Taylor
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Paper Abstract

We demonstrate ultrafast dynamical imaging of surfaces using a scanning tunneling microscope with a low-temperature-grown GaAs tip photoexcited by 100-fs, 800-nm pulses. We detect picosecond transients on a coplanar stripline and demonstrate a temporal resolution (full-width at half maximum) of 1.7 ps. By dynamically imaging the stripline, we demonstrate that the local conductivity in the sample is reflected in the transient correlated current and that 20-nm spatial resolution is achievable for a 2 ps transient, correlated signal. We apply this technique of photoconductively-gated ultrafast scanning tunneling microscopy (PG-USTM) to study carrier dynamics in InAs/GaAs self-assembled quantum dot samples (SAQD) at T=300 K. The initial carrier relaxation proceeds via Auger carrier capture from the InAs wetting layer (WL) on a timescale of 1-2 ps, followed by recombination of carriers on a 900 ps timescale. Finally, we demonstrate junction-mixing ultrafast STM (JM-USTM) using picosecond voltage pulses propagating on a patterned metal-on-metal (Ti/Pt). Using JM-USTM we have achieved a spatio/temporal resolution of 2 nm/20 ps.

Paper Details

Date Published: 11 June 2002
PDF: 12 pages
Proc. SPIE 4643, Ultrafast Phenomena in Semiconductors VI, (11 June 2002); doi: 10.1117/12.470421
Show Author Affiliations
Dzmitry A. Yarotski, Los Alamos National Lab. (United States)
Giovanni P. Donati, Los Alamos National Lab. (United States)
Antoinette J. Taylor, Los Alamos National Lab. (United States)

Published in SPIE Proceedings Vol. 4643:
Ultrafast Phenomena in Semiconductors VI
Kong-Thon F. Tsen; Jin-Joo Song; Hongxing Jiang, Editor(s)

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