Berlin 2018 – wissenschaftliches Programm

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O: Fachverband Oberflächenphysik

O 97: Scanning probe techniques: Method development II

O 97.1: Vortrag

Donnerstag, 15. März 2018, 15:00–15:15, MA 005

Nanosecond time resolution in Electrostatic Force Microscopy — •Riccardo Borgani, Daniel Forchheimer, Per-Anders Thorén, and David B. Haviland — Nanostructure Physics, KTH Royal Institute of Technology, Stockholm, Sweden

We introduce a scanning probe microscopy technique based on nonlinear electrostatic interaction to map the fast response of a surface to an electric or luminous stimulus. The technique allows for investigation of the fast generation and recombination of charge, e.g. in photo-voltaic materials.

We excite the probe at its resonance frequency, and the material under study with a periodic train of sharp pulses. We drive the cantilever and monitor its deflection near its mechanical resonance frequency, where a high SNR measurement of intermodulation between the drive and the material response to the pulses is possible. The proposed technique is able to reconstruct the rise and fall time of the material response from hundreds of milliseconds to the nanosecond regime.

We show experimental data demonstrating this time resolution, and we discuss the theory and simulations that suggest a even faster time resolution is achievable at the expense of the measurement time. Our work demonstrates how the intermodulation spectral technique, where phase-coherent down-conversion is measured at many frequencies, is an attractive alternative to pump-probe measurements for probing fast dynamics.