Artifacts in time-resolved Kelvin probe force microscopy
Kelvin probe force microscopy (KPFM) has been used for the characterization of metals, insulators, and semiconducting materials on the nanometer scale. Especially in semiconductors, the charge dynamics are of high interest. Recently, several techniques for time-resolved measurements with time resolu...
Main Authors: | , , |
---|---|
Format: | Article |
Language: | English |
Published: |
Beilstein-Institut
2018-04-01
|
Series: | Beilstein Journal of Nanotechnology |
Subjects: | |
Online Access: | https://doi.org/10.3762/bjnano.9.119 |
id |
doaj-24a0ba669ae345df8f6337bbf4a9bd86 |
---|---|
record_format |
Article |
spelling |
doaj-24a0ba669ae345df8f6337bbf4a9bd862020-11-24T21:02:28ZengBeilstein-InstitutBeilstein Journal of Nanotechnology2190-42862018-04-01911272128110.3762/bjnano.9.1192190-4286-9-119Artifacts in time-resolved Kelvin probe force microscopySascha Sadewasser0Nicoleta Nicoara1Santiago D. Solares2International Iberian Nanotechnology Laboratory, Av. Mestre José Veiga s/n, 4715-330 Braga, PortugalInternational Iberian Nanotechnology Laboratory, Av. Mestre José Veiga s/n, 4715-330 Braga, PortugalThe George Washington University, Department of Mechanical and Aerospace Engineering, 800 22nd St. NW, Ste. 3000, Washington, DC 20052, USAKelvin probe force microscopy (KPFM) has been used for the characterization of metals, insulators, and semiconducting materials on the nanometer scale. Especially in semiconductors, the charge dynamics are of high interest. Recently, several techniques for time-resolved measurements with time resolution down to picoseconds have been developed, many times using a modulated excitation signal, e.g., light modulation or bias modulation that induces changes in the charge carrier distribution. For fast modulation frequencies, the KPFM controller measures an average surface potential, which contains information about the involved charge carrier dynamics. Here, we show that such measurements are prone to artifacts due to frequency mixing, by performing numerical dynamics simulations of the cantilever oscillation in KPFM subjected to a bias-modulated signal. For square bias pulses, the resulting time-dependent electrostatic forces are very complex and result in intricate mixing of frequencies that may, in some cases, have a component at the detection frequency, leading to falsified KPFM measurements. Additionally, we performed fast Fourier transform (FFT) analyses that match the results of the numerical dynamics simulations. Small differences are observed that can be attributed to transients and higher-order Fourier components, as a consequence of the intricate nature of the cantilever driving forces. These results are corroborated by experimental measurements on a model system. In the experimental case, additional artifacts are observed due to constructive or destructive interference of the bias modulation with the cantilever oscillation. Also, in the case of light modulation, we demonstrate artifacts due to unwanted illumination of the photodetector of the beam deflection detection system. Finally, guidelines for avoiding such artifacts are given.https://doi.org/10.3762/bjnano.9.119Kelvin probe force microscopytime-resolved |
collection |
DOAJ |
language |
English |
format |
Article |
sources |
DOAJ |
author |
Sascha Sadewasser Nicoleta Nicoara Santiago D. Solares |
spellingShingle |
Sascha Sadewasser Nicoleta Nicoara Santiago D. Solares Artifacts in time-resolved Kelvin probe force microscopy Beilstein Journal of Nanotechnology Kelvin probe force microscopy time-resolved |
author_facet |
Sascha Sadewasser Nicoleta Nicoara Santiago D. Solares |
author_sort |
Sascha Sadewasser |
title |
Artifacts in time-resolved Kelvin probe force microscopy |
title_short |
Artifacts in time-resolved Kelvin probe force microscopy |
title_full |
Artifacts in time-resolved Kelvin probe force microscopy |
title_fullStr |
Artifacts in time-resolved Kelvin probe force microscopy |
title_full_unstemmed |
Artifacts in time-resolved Kelvin probe force microscopy |
title_sort |
artifacts in time-resolved kelvin probe force microscopy |
publisher |
Beilstein-Institut |
series |
Beilstein Journal of Nanotechnology |
issn |
2190-4286 |
publishDate |
2018-04-01 |
description |
Kelvin probe force microscopy (KPFM) has been used for the characterization of metals, insulators, and semiconducting materials on the nanometer scale. Especially in semiconductors, the charge dynamics are of high interest. Recently, several techniques for time-resolved measurements with time resolution down to picoseconds have been developed, many times using a modulated excitation signal, e.g., light modulation or bias modulation that induces changes in the charge carrier distribution. For fast modulation frequencies, the KPFM controller measures an average surface potential, which contains information about the involved charge carrier dynamics. Here, we show that such measurements are prone to artifacts due to frequency mixing, by performing numerical dynamics simulations of the cantilever oscillation in KPFM subjected to a bias-modulated signal. For square bias pulses, the resulting time-dependent electrostatic forces are very complex and result in intricate mixing of frequencies that may, in some cases, have a component at the detection frequency, leading to falsified KPFM measurements. Additionally, we performed fast Fourier transform (FFT) analyses that match the results of the numerical dynamics simulations. Small differences are observed that can be attributed to transients and higher-order Fourier components, as a consequence of the intricate nature of the cantilever driving forces. These results are corroborated by experimental measurements on a model system. In the experimental case, additional artifacts are observed due to constructive or destructive interference of the bias modulation with the cantilever oscillation. Also, in the case of light modulation, we demonstrate artifacts due to unwanted illumination of the photodetector of the beam deflection detection system. Finally, guidelines for avoiding such artifacts are given. |
topic |
Kelvin probe force microscopy time-resolved |
url |
https://doi.org/10.3762/bjnano.9.119 |
work_keys_str_mv |
AT saschasadewasser artifactsintimeresolvedkelvinprobeforcemicroscopy AT nicoletanicoara artifactsintimeresolvedkelvinprobeforcemicroscopy AT santiagodsolares artifactsintimeresolvedkelvinprobeforcemicroscopy |
_version_ |
1716775286605873152 |