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EFM data mapped into 2D images of tip-sample contact potential difference and capacitance second derivative.

Lilliu S, Maragliano C, Hampton M, Elliott M, Stefancich M, Chiesa M, Dahlem MS, Macdonald JE - Sci Rep (2013)

Bottom Line: The only required equipment consists of a microscope with lift-mode EFM capable of phase shift detection.An open-source MATLAB Graphical User Interface (GUI) for images acquisition, processing and analysis has been developed.The technique is tested with Indium Tin Oxide (ITO) and with poly(3-hexylthiophene) (P3HT) nanowires for organic transistor applications.

View Article: PubMed Central - PubMed

Affiliation: 1] School of Physics and Astronomy, Cardiff University, Queens Buildings, The Parade, Cardiff CF243AA, United Kingdom [2] Masdar Institute of Science and Technology, PO Box 54224, Abu Dhabi, United Arab Emirates.

ABSTRACT
We report a simple technique for mapping Electrostatic Force Microscopy (EFM) bias sweep data into 2D images. The method allows simultaneous probing, in the same scanning area, of the contact potential difference and the second derivative of the capacitance between tip and sample, along with the height information. The only required equipment consists of a microscope with lift-mode EFM capable of phase shift detection. We designate this approach as Scanning Probe Potential Electrostatic Force Microscopy (SPP-EFM). An open-source MATLAB Graphical User Interface (GUI) for images acquisition, processing and analysis has been developed. The technique is tested with Indium Tin Oxide (ITO) and with poly(3-hexylthiophene) (P3HT) nanowires for organic transistor applications.

No MeSH data available.


P3HT nanowires probed by SPP-EFM.(a) Height [nm]. (b) Goodness of fit R2. (c) Deconvolved channel proportional to the second derivative of the tip-sample capacitance A = (Q/2K)∂2C/∂z2 [°V−2]. (d) Deconvolved channel corresponding to the tip-sample contact potential difference VCPD [V].
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f3: P3HT nanowires probed by SPP-EFM.(a) Height [nm]. (b) Goodness of fit R2. (c) Deconvolved channel proportional to the second derivative of the tip-sample capacitance A = (Q/2K)∂2C/∂z2 [°V−2]. (d) Deconvolved channel corresponding to the tip-sample contact potential difference VCPD [V].

Mentions: Poly(3-hexylthiophene-2,5-diyl) nanowires dispersed in anisole (purity 99%, Sigma-Aldrich, UK) were spincoated on a Si/SiO2 substrate and annealed for 30 minutes at 140°C. As shown in Figure 3, the wires have an average width and a thickness of ~60 nm. Figure 4 shows the following normalized channels: height, capacitance (Channel A) and VCPD (Channel B). The height line profile is not correlated with the capacitance (ρ = 0.02) and the VCPD (ρ = 0.12) line profiles, while capacitance and VCPD are highly correlated (ρ = 0.6). This is because the sample is heterogeneous (both Si substrate and nanowires are imaged simultaneously). The drift in the VCPD, along the y-scan direction (top-bottom), could be an effect of tip contamination24. However, VCPD contrast is visible between wires and substrate because of their strong difference in work-function. Values of VCPD at the left borders of the nanowires are affected by high error, as shown by the goodness of fit channel. This could be due to asymmetries in the tip shape or hysteresis of the piezo, resulting in discrepancies between trace and retrace channels, in correspondence of sharp features. In the case of the piezo hysteresis, this effect could be probably avoided by performing the technique with just one trace or retrace channel, at the expense of losing in resolution and doubling the time required for a scan38.


EFM data mapped into 2D images of tip-sample contact potential difference and capacitance second derivative.

Lilliu S, Maragliano C, Hampton M, Elliott M, Stefancich M, Chiesa M, Dahlem MS, Macdonald JE - Sci Rep (2013)

P3HT nanowires probed by SPP-EFM.(a) Height [nm]. (b) Goodness of fit R2. (c) Deconvolved channel proportional to the second derivative of the tip-sample capacitance A = (Q/2K)∂2C/∂z2 [°V−2]. (d) Deconvolved channel corresponding to the tip-sample contact potential difference VCPD [V].
© Copyright Policy - open-access
Related In: Results  -  Collection

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getmorefigures.php?uid=PMC3842085&req=5

f3: P3HT nanowires probed by SPP-EFM.(a) Height [nm]. (b) Goodness of fit R2. (c) Deconvolved channel proportional to the second derivative of the tip-sample capacitance A = (Q/2K)∂2C/∂z2 [°V−2]. (d) Deconvolved channel corresponding to the tip-sample contact potential difference VCPD [V].
Mentions: Poly(3-hexylthiophene-2,5-diyl) nanowires dispersed in anisole (purity 99%, Sigma-Aldrich, UK) were spincoated on a Si/SiO2 substrate and annealed for 30 minutes at 140°C. As shown in Figure 3, the wires have an average width and a thickness of ~60 nm. Figure 4 shows the following normalized channels: height, capacitance (Channel A) and VCPD (Channel B). The height line profile is not correlated with the capacitance (ρ = 0.02) and the VCPD (ρ = 0.12) line profiles, while capacitance and VCPD are highly correlated (ρ = 0.6). This is because the sample is heterogeneous (both Si substrate and nanowires are imaged simultaneously). The drift in the VCPD, along the y-scan direction (top-bottom), could be an effect of tip contamination24. However, VCPD contrast is visible between wires and substrate because of their strong difference in work-function. Values of VCPD at the left borders of the nanowires are affected by high error, as shown by the goodness of fit channel. This could be due to asymmetries in the tip shape or hysteresis of the piezo, resulting in discrepancies between trace and retrace channels, in correspondence of sharp features. In the case of the piezo hysteresis, this effect could be probably avoided by performing the technique with just one trace or retrace channel, at the expense of losing in resolution and doubling the time required for a scan38.

Bottom Line: The only required equipment consists of a microscope with lift-mode EFM capable of phase shift detection.An open-source MATLAB Graphical User Interface (GUI) for images acquisition, processing and analysis has been developed.The technique is tested with Indium Tin Oxide (ITO) and with poly(3-hexylthiophene) (P3HT) nanowires for organic transistor applications.

View Article: PubMed Central - PubMed

Affiliation: 1] School of Physics and Astronomy, Cardiff University, Queens Buildings, The Parade, Cardiff CF243AA, United Kingdom [2] Masdar Institute of Science and Technology, PO Box 54224, Abu Dhabi, United Arab Emirates.

ABSTRACT
We report a simple technique for mapping Electrostatic Force Microscopy (EFM) bias sweep data into 2D images. The method allows simultaneous probing, in the same scanning area, of the contact potential difference and the second derivative of the capacitance between tip and sample, along with the height information. The only required equipment consists of a microscope with lift-mode EFM capable of phase shift detection. We designate this approach as Scanning Probe Potential Electrostatic Force Microscopy (SPP-EFM). An open-source MATLAB Graphical User Interface (GUI) for images acquisition, processing and analysis has been developed. The technique is tested with Indium Tin Oxide (ITO) and with poly(3-hexylthiophene) (P3HT) nanowires for organic transistor applications.

No MeSH data available.