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Advances in Optical Technologies
Volume 2011 (2011), Article ID 510186, 9 pages
Research Article

Laser-Combined Scanning Tunneling Microscopy on the Carrier Dynamics in Low-Temperature-Grown GaAs/AlGaAs/GaAs

Institute of Applied Physics, University of Tsukuba, Tsukuba 307-8573, Japan

Received 31 May 2011; Accepted 26 August 2011

Academic Editor: Qingming Luo

Copyright © 2011 Yasuhiko Terada et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


We investigated carrier recombination dynamics in a low-temperature-grown GaAs (LT-GaAs)/AlGaAs/GaAs heterostructure by laser-combined scanning tunneling microscopy, shaken-pulse-pair-excited STM (SPPX-STM). With the AlGaAs interlayer as a barrier against the flow of photocarriers, recombination lifetimes in LT-GaAs of 4.0 ps and GaAs of 4.8 ns were successfully observed separately. We directly demonstrated the high temporal resolution of SPPX-STM by showing the recombination lifetime of carriers in LT-GaAs (4.0 ps) in the range of subpicosecond temporal resolution. In the carrier-lifetime-mapping measurement, a blurring of recombination lifetime up to 50 nm was observed at the LT-GaAs/AlGaAs boundary, which was discussed in consideration of the screening length of the electric field from the STM probe. The effect of the built-in potential on the signal, caused by the existence of LT-GaAs/AlGaAs/GaAs boundaries, was discussed in detail.