ISSN:
1089-7623
Source:
AIP Digital Archive
Topics:
Physics
,
Electrical Engineering, Measurement and Control Technology
Notes:
We have developed an instrument for optically measuring carrier dynamics in thin-film materials with ∼150 nm lateral resolution, ∼250 fs temporal resolution, and high sensitivity. This is achieved by combining ultrafast pump-probe laser spectroscopic techniques, which measure carrier dynamics with femtosecond-scale temporal resolution, with the nanometer-scale lateral resolution of near-field scanning optical microscopes (NSOMs). We employ a configuration in which carriers are excited by a far-field pump laser pulse and locally measured by a probe pulse sent through a NSOM tip and transmitted through the sample in the near field. A novel detection system allows for either two-color or degenerate pump and probe photon energies, permitting greater measurement flexibility over earlier published work. The capabilities of this instrument are proven through near-field degenerate pump-probe studies of carrier dynamics in GaAs/AlGaAs single quantum well samples locally patterned by focused-ion-beam (FIB) implantation. We find that lateral carrier diffusion across the nanometer-scale FIB pattern plays a significant role in the decay time of the excited carriers within ∼1 μm of the implanted stripes, an effect which could not have been resolved with a far-field system. © 1999 American Institute of Physics.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1063/1.1149841
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