Cross-talk artefacts in Kelvin probe force microscopy imaging: A comprehensive study

Barbet, S.; Popoff, Michel‐Robert; Diesinger, H.; Deresmes, D.; Théron, Didier; Mélin, Thierry

doi:10.1063/1.4870710

Cited by 49 publications

(60 citation statements)

References 15 publications

(6 reference statements)

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“…It has been shown that AM-KPFM is susceptible to internal AC-signal couplings which can lead to a topography-dependent offset in the applied voltage. [ 68 ] Thus, to ensure no topography pick up we measure the cantilever response to electrostatic excitation in both the in-and out-of-phase channels across the entire resonance. The response is that of a simple harmonic oscillator, without any sign of AC coupling.…”

Section: Methodsmentioning

confidence: 99%

Nanoimaging of Open‐Circuit Voltage in Photovoltaic Devices

Tennyson

Garrett

Frantz

et al. 2015

Advanced Energy Materials

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voltage and the overall electrical behavior of a device strongly depend on the nonradiative recombination rate of the charge carriers within a material, which is affected by the defects inherently present within the semiconductor. Despite all the efforts in developing higher performance thin-fi lm polycrystalline solar cells, such as CdTe, CuIn x Ga (1− x ) Se 2 (CIGS), and Cu 2 ZnSnS 4 (CZTS), the difference between the theoretically predicted and the best experimentally achieved V oc is still considerably large (up to 0.6 V). [ 2,3 ] For Si, extensive research has been dedicated to design and implement nanostructured light-trapping architectures to boost light absorption; [4][5][6][7] however, there are very few experiments showing how the V oc is affected. For organic PV blends, the limited V oc observed in most bulk heterojunction solar cells is attributed to geminate and nongeminate losses; [ 8,9 ] nevertheless, local variations in V oc have never been measured. Thus, for any micrometer-and nanoscale structured PV device, assessing variations in V oc with nanoscale resolution and spatially resolving where recombination occurs within the material can potentially change the pathway for designing higher performance devices.Imaging methods based on atomic force microscopy (AFM) techniques have been extensively used to characterize the structural and electrical properties of PV materials and full devices. [10][11][12][13][14][15][16][17][18][19][20][21] In particular, Kelvin probe force microscopy (KPFM) has been implemented to probe the electrical characteristics of a variety of PV materials and devices, ranging from organic materials [ 9,[22][23][24] and oxides [ 25 ] to III-V semiconductors for multijunction designs [26][27][28] and polycrystalline thin fi lms. [ 18,[29][30][31][32][33][34][35] The local optoelectronic properties and changes in material composition have also been mapped using near-fi eld scanning optical microscopy (NSOM) probes as local sources of excitation. [36][37][38][39][40][41][42] Very recently, photoluminescence has emerged as a promising tool to map charge recombination [43][44][45] and carriers diffusion [ 46 ] with high spatial resolution. At low temperature (70 K), photoluminescence imaging with submicrometer resolution has been implemented to map a 10 meV quasi-Fermi level splitting in CIGS solar cells, where variations in the intensity signal were attributed to changes in the material composition. [ 47 ] Nevertheless, none of these imaging techniques provide a direct measurement of V oc within the material at operating conditions. A straightforward, universal, and accurate method to measure the V oc (and hence nonradiative recombination processes) with high spatial resolution in PV materials is still missing.Here, we present a new imaging technique based on illuminated KPFM to map the V oc of optoelectronic devices with nanoscale resolution <100 nm. We map the contact potential difference (CPD) of half or fully processed solar cells in the For most photovoltaic (PV) devices, the...

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Section: Methodsmentioning

confidence: 99%

Nanoimaging of Open‐Circuit Voltage in Photovoltaic Devices

Tennyson

Garrett

Frantz

et al. 2015

Advanced Energy Materials

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“…nonlocal cantilever contributions), since these contributions are subtracted. It should be noted, that the intrinsic capacitance gradient is still dependent on the sample geometry and dimensions since they determine the overall electric polarization of the sample, and hence, the force acting on the tip [31][32][33][34]. Experimentally the topographic crosstalk capacitance gradient image can be constructed following the procedure that we applied for the case of capacitance measurements in Ref.…”

Section: Topographic Crosstalk In Lift-mode Efmmentioning

confidence: 99%

“…As a consequence, the tip-substrate distance varies during the image acquisition, thus inducing spurious capacitance variations that are not related to the dielectric properties of the sample. That is, dielectric images of non-planar samples can be severely affected by topographic crosstalks [31][32][33][34].…”

Section: Introductionmentioning

confidence: 99%

Nanoscale dielectric microscopy of non-planar samples by lift-mode electrostatic force microscopy

et al. 2016

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Lift-mode electrostatic force microscopy (EFM) is one of the most convenient imaging modes to study the local dielectric properties of non-planar samples. Here we present the quantitative analysis of this imaging mode. We introduce a method to quantify and subtract the topographic crosstalk from the lift-mode EFM images, and a 3D numerical approach that allows for extracting the local dielectric constant with nanoscale spatial resolution free from topographic artifacts. We demonstrate this procedure by measuring the dielectric properties of micropatterned SiO 2 pillars and of single bacteria cells, thus illustrating the wide applicability of our approach from materials science to biology.

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“…These include Kelvin probe force microscopy, 225,226 electroluminescence measurements, UV-visible spectrometry for bandgap determination, and time-resolved photoluminescence spectroscopy, as detailed in the introduction, with additional useful explanations in the PES section. For example, time-resolved photoluminescence measurements often show single crystals to have a fast initial decay, followed by a slower decay.…”

Section: Chemistry Of Materialsmentioning

confidence: 99%

Perovskite-Inspired Photovoltaic Materials: Toward Best Practices in Materials Characterization and Calculations

et al. 2017

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ABSTRACT:Recently, there has been an explosive growth in research based on hybrid lead-halide perovskites for photovoltaics owing to rapid improvements in efficiency. The advent of these materials for solar applications has led to widespread interest in understanding the key enabling properties of these materials. This has resulted in renewed interest in related compounds and a search for materials that may replicate the defect-tolerant properties and long lifetimes of the hybrid lead-halide perovskites. Given the rapid pace of development of the field, the rises in efficiencies of these systems have outpaced the more basic understanding of these materials. Measuring or calculating the basic properties, such as crystal/electronic structure and composition, can be challenging because some of these materials have anisotropic structures, and/or are composed of both heavy metal cations and volatile, mobile, light elements. Some consequences are beam damage during characterization, composition change under vacuum, or compound effects, such as the alteration of the electronic structure through the influence of the substrate. These effects make it challenging to understand the basic properties integral to optoelectronic operation. Compounding these difficulties is the rapid pace with which the field progresses. This has created an ongoing need to continually evaluate best practices with respect to characterization and calculations, as well as to identify inconsistencies in reported values to determine if those inconsistencies are rooted in characterization methodology or materials synthesis. This article describes the difficulties in characterizing hybrid lead-halide perovskites and new materials, and how these challenges may be overcome. 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 2 challenges discussed. The focus in this article is on crystallography, composition measurements, photoemission spectroscopy and calculations on perovskites and new, related absorbers. We suggest how some of the important artifacts could be avoided and how the reporting for each technique could be streamlined between groups to ensure reproducibility as the field progresses.

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Cross-talk artefacts in Kelvin probe force microscopy imaging: A comprehensive study

Cited by 49 publications

References 15 publications

Nanoimaging of Open‐Circuit Voltage in Photovoltaic Devices

Nanoimaging of Open‐Circuit Voltage in Photovoltaic Devices

Nanoscale dielectric microscopy of non-planar samples by lift-mode electrostatic force microscopy

Perovskite-Inspired Photovoltaic Materials: Toward Best Practices in Materials Characterization and Calculations

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