Demonstration of high-spatial resolution in ultrafast scanning tunneling microscopy

Dzmitry A. Yarotski; Giovanni P. Donati; Antoinette J. Taylor

doi:10.1117/12.470421

11 June 2002 Demonstration of high spatial resolution in ultrafast scanning tunneling microscopy

Dzmitry A. Yarotski, Giovanni P. Donati, Antoinette J. Taylor

Proceedings Volume 4643, Ultrafast Phenomena in Semiconductors VI; (2002) https://doi.org/10.1117/12.470421
Event: Symposium on Integrated Optoelectronic Devices, 2002, San Jose, California, United States

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.

Citation Download Citation

Dzmitry A. Yarotski, Giovanni P. Donati, and Antoinette J. Taylor "Demonstration of high spatial resolution in ultrafast scanning tunneling microscopy", Proc. SPIE 4643, Ultrafast Phenomena in Semiconductors VI, (11 June 2002); https://doi.org/10.1117/12.470421

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