KPFM probe

Boron doped diamond (BDD) has great potential in electrical, and electrochemical sensing applications. The growth parameters, substrates, and synthesis method play a vital role in the preparation of semiconducting BDD to metallic BDD. Doping of other elements along with boron (B) into diamond demonstrated improved efficacy of B doping and exceptional properties.*

In the article “Influence of B/N co-doping on electrical and photoluminescence properties of CVD grown homoepitaxial diamond films” Srinivasu Kunuku, Mateusz Ficek, Aleksandra Wieloszynska, Magdalena Tamulewicz-Szwajkowska, Krzysztof Gajewski, Miroslaw Sawczak, Aneta Lewkowicz, Jacek Ryl, Tedor Gotszalk and Robert Bogdanowicz describe how B and nitrogen (N) co-doped diamond has been synthesized on single crystalline diamond (SCD) IIa and SCD Ib substrates in a microwave plasma-assisted chemical vapor deposition process.*

The surface topography of the CVD diamond layers was investigated using atomic force microscopy (AFM), and Kelvin probe force microscopy (KPFM) was employed to measure the contact potential difference (CPD) to calculate the work function of these CVD diamond layers.*

Atomic force microscopy topography depicted the flat and smooth surface with low surface roughness for low B doping, whereas surface features like hillock structures and un-epitaxial diamond crystals with high surface roughness were observed for high B doping concentrations. KPFM measurements revealed that the work function (4.74–4.94 eV) has not varied significantly for CVD diamond synthesized with different B/C concentrations.*

NanoWorld ARROW-EFM conductive platinumirdidium5 coated AFM probes with a typical spring constant of 2.8 N/m and a typical resonant frequency of 75 kHz were used.*

Figure 2 from “Influence of B/N co-doping on electrical and photoluminescence properties of CVD grown homoepitaxial diamond films “ by Srinivasu Kunuku et al: AFM topography of B/N co-doped CVD diamond on (with fixed N/C = 0.02) SCD IIa; (a) B/C ∼ 2500 ppm (b) B/C ∼ 5000 ppm (c) B/C ∼ 7500 ppm, and KPFM CPD images of B/N co-doped CVD diamond (with fixed N/C = 0.02) on SCD IIa; (d) B/C ∼ 2500 ppm (e) B/C ∼ 5000 ppm (f) B/C ∼ 7500 ppm. NanoWorld Arrow-EFM platinumiridium coated AFM probes were used for the KPFM and surface topography measurements. — Figure 2 from “Influence of B/N co-doping on electrical and photoluminescence properties of CVD grown homoepitaxial diamond films “ by Srinivasu Kunuku et al:
AFM topography of B/N co-doped CVD diamond on (with fixed N/C = 0.02) SCD IIa; (a) B/C ∼ 2500 ppm (b) B/C ∼ 5000 ppm (c) B/C ∼ 7500 ppm, and KPFM CPD images of B/N co-doped CVD diamond (with fixed N/C = 0.02) on SCD IIa; (d) B/C ∼ 2500 ppm (e) B/C ∼ 5000 ppm (f) B/C ∼ 7500 ppm.

*Srinivasu Kunuku, Mateusz Ficek, Aleksandra Wieloszynska, Magdalena Tamulewicz-Szwajkowska, Krzysztof Gajewski, Miroslaw Sawczak, Aneta Lewkowicz, Jacek Ryl, Tedor Gotszalk and Robert Bogdanowicz
Influence of B/N co-doping on electrical and photoluminescence properties of CVD grown homoepitaxial diamond films
Nanotechnology (2022), 33 125603
DOI: https://doi.org/10.1088/1361-6528/ac4130

Please follow this external link to read the full article: https://doi.org/10.1088/1361-6528/ac4130

Open Access The article “Influence of B/N co-doping on electrical and photoluminescence properties of CVD grown homoepitaxial diamond films” by Srinivasu Kunuku, Mateusz Ficek, Aleksandra Wieloszynska, Magdalena Tamulewicz-Szwajkowska, Krzysztof Gajewski, Miroslaw Sawczak, Aneta Lewkowicz, Jacek Ryl, Tedor Gotszalk and Robert Bogdanowicz is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. The images or other third party material in this article are included in the article’s Creative Commons license, unless indicated otherwise in a credit line to the material. If material is not included in the article’s Creative Commons license and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this license, visit http://creativecommons.org/licenses/by/4.0/.

Kelvin Probe Force Microscopy ( KPFM ) is a scanning probe microscopy technique. It is a combination of the Kelvin probe and of Atomic Force Microscopy methods. The technique consists in evaluating the difference in work function between two conducting materials, by using a nanometer scale tip ( the “KPFMtip”), and placing it close to the material to be characterised, where a difference in work function leads to an electrostatic force developing between the two, which is translated as an oscillation of the tip’s cantilever. A bia sapplied via an external circuit is varied until the force and hence the electrostatic field between sample and KPFM tip is cancelled.*

In the article “KPFM surface photovoltage measurement and numerical simulation” Clément Marchat, James P. Connolly, Jean-Paul Kleider, José Alvarez, Lejo J. Koduvelikulathu and Jean Baptiste Puel present a method for the analysis of Kelvin probe force microscopy (KPFM) characterization of semiconductor devices.
It enables evaluation of the influence of defective surface layers. The model is validated by analysing experimental KPFM measurements on crystalline silicon samples of contact potential difference (VCPD) in the dark and under illumination, and hence the surface photovoltage (SPV). It is shown that the model phenomenologically explains the observed KPFM measurements. It reproduces the magnitude of SPV characterization as a function of incident light power in terms of a defect density assuming Gaussian defect distribution in the semiconductor bandgap. This allows an estimation of defect densities in surface layers of semiconductors and therefore increased exploitation of KPFM data.*

The KPFM measurements were performed using NanoWorld ARROW-EFM conductive AFM tips with a PtIr coating.
The tip work function didn’t require calibration because only SPV measurement were performed and studied. Measurements were performed in the KPFM amplitude modulation (AM)mode rather than the frequency modulation (FM) one. The AM mode was chosen because lateral resolution was not a problem on the homogeneous bulk samples studied, allowing focus on the superior surface potential resolution that can be achieved with the AM mode.*

Fig. 1 from “*KPFM surface photovoltage measurement and numerical simulation*” by Clément Marchat et al:
Kelvin probe force microscopy setup schematic. The conducting cantilever carrying the KPFM tip is scanned over a surface while AC + DC potential is applied. The AC signal is a sinusoid whose frequency matches the mechanical resonance of the cantilever. The four-quadrant detector provides feedback in order to minimise cantilever oscillation by varying the DC signal thereby yielding the sample work function compared to the tip one.

*Clément Marchat, James P. Connolly, Jean-Paul Kleider, José Alvarez, Lejo J. Koduvelikulathu and Jean Baptiste Puel
KPFM surface photovoltage measurement and numerical simulation
EPJ Photovoltaics10, 3 (2019)
DOI: https://doi.org/10.1051/epjpv/2019002

Please follow this external link to read the full article: https://www.epj-pv.org/articles/epjpv/abs/2019/01/pv180014/pv180014.html

Open Access The article “KPFM surface photovoltage measurement and numerical simulation “ by Clément Marchat, James P. Connolly, Jean-Paul Kleider, José Alvarez, Lejo J. Koduvelikulathu and Jean Baptiste Puel is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. The images or other third party material in this article are included in the article’s Creative Commons license, unless indicated otherwise in a credit line to the material. If material is not included in the article’s Creative Commons license and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this license, visit http://creativecommons.org/licenses/by/4.0/.