Artifacts in time-resolved Kelvin probe force microscopy

Sadewasser, Sascha; Nicoara, Nicoleta; Solares, Santiago D.

doi:10.3762/bjnano.9.119

Cited by 10 publications

(13 citation statements)

References 33 publications

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“…For the modulated light a fast switched diode laser (PicoQuant FSL500) was externally triggered using user-defined signal patterns, avoiding any frequencies which could lead to artifacts due to frequency mixing. [49] Device Processing: Devices were fabricated by two subsequent direct photolithography steps. First, the contacts were defined by removing i-ZnO using a solution of aqueous HCl (0.5%) for 15 s. Subsequently, without removing the photoresist, the Cr/Au contacts (thickness of 6 and 30 nm, respectively) were deposited by sputtering immediately after opening the via to prevent oxidation.…”

Section: Methodsmentioning

confidence: 99%

Wafer‐Scale Fabrication of 2D β‐In₂Se₃ Photodetectors

Claro

Grzonka

Nicoara

et al. 2020

Advanced Optical Materials

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Nevertheless, the research of 2D materials is still in its early stages. The field started with graphene several years ago, [3] but more materials have been added continuously to the list. Among these, transition metal dichalcogenides (TMDC), [4] which have impressive optical properties in the visible range, are currently one of the most studied 2D materials. Devices made of these materials have shown remarkable performance as photodetectors, [5,6] nonvolatile random access memory, [7] or photovoltaics, [8] even when using simple manual exfoliation methods. More recently, 2D indium selenides (In x Se y) have gained attention, [9] due to their bandgap in the visible spectral region, comparable to TMDCs, but also due to several novel properties: InSe exhibits one of the largest mobilities of 2D semiconductor materials, [10] and β-In 2 Se 3 shows good mobility, [11] excellent photoresponsivity, [12] and exotic ferroelectricity [13] (the ordered ferroelectric phase is also called β′-In 2 Se 3 by some authors). [11,13] Transistors with high mobility and on/off ratio have already been realized. [14] Therefore, 2D In 2 Se 3 materials have the potential to address several limitations of the current silicon (Si) and III-V technologies, such as improved mobility and overall performance of transistors for electronics, as well as integrated photodetectors and light emitters in the same material system (same die), all possible on virtually any substrate, including transparent and flexible substrates. [15,16] Yet, the majority of reported devices from 2D materials rely on fabrication methods based on exfoliation and transfer of layers onto other substrates or other 2D materials. While this device fabrication process allows unprecedented flexibility in the combination of materials and therefore has nearly unlimited device design possibilities, [1] it leads typically to individual or few devices and is a slow and tedious process. On the other hand, due to their layered nature, instead of strong covalent bonds (as in Si and compound semiconductors) van der Waals forces exist between the layers. Hence, 2D materials can be grown epitaxially on substrates with completely different lattice constants without creating the strain and the defects commonly found in mismatched heteroepitaxy. This method is called van der Waals (vdW) epitaxy. [17] Nevertheless, the substrate does influence the growth, [18] as it modifies the nucleation of the first layer. Some substrates provide growth with superior quality (amount of defects, 2D materials are considered the future of electronics and photonics, stimulated by their remarkable performance. Among the 2D materials family, β-In 2 Se 3 shows good mobility, excellent photoresponsivity, and exotic ferroelectricity, making it suitable for a wide variety of applications. To date, most reported devices from 2D materials in general, and β-In 2 Se 3 in specific, rely on cumbersome fabrication methods using mechanical exfoliation and transfer of layers onto other substrates. However, for a successful ado...

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Section: Methodsmentioning

confidence: 99%

Wafer‐Scale Fabrication of 2D β‐In₂Se₃ Photodetectors

Claro

Grzonka

Nicoara

et al. 2020

Advanced Optical Materials

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“…The surface photovoltage is defined as: SPV = CPD under illumination − CPD in dark . For the modulated light, a fast switched diode laser (PicoQuant FSL500) was externally triggered via user-defined signal patterns, avoiding any frequencies which could lead to artifacts due to frequency mixing 68 . The light sources have an optical power of ∼4.5 mW (with an intensity of~100 mW cm −2 ) and an illumination angle of 28°, to ensure illumination of the sample under the tip and cantilever beam.…”

Section: Jð1þ Jð0þmentioning

confidence: 99%

Chemical instability at chalcogenide surfaces impacts chalcopyrite devices well beyond the surface

et al. 2020

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The electrical and optoelectronic properties of materials are determined by the chemical potentials of their constituents. The relative density of point defects is thus controlled, allowing to craft microstructure, trap densities and doping levels. Here, we show that the chemical potentials of chalcogenide materials near the edge of their existence region are not only determined during growth but also at room temperature by post-processing. In particular, we study the generation of anion vacancies, which are critical defects in chalcogenide semiconductors and topological insulators. The example of CuInSe 2 photovoltaic semiconductor reveals that single phase material crosses the phase boundary and forms surface secondary phases upon oxidation, thereby creating anion vacancies. The arising metastable point defect population explains a common root cause of performance losses. This study shows how selective defect annihilation is attained with tailored chemical treatments that mitigate anion vacancy formation and improve the performance of CuInSe 2 solar cells.

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“… 24 , 27 , 28 Limitations and possible artifacts of this approach have also been investigated by a number of groups. 27 , 29 Murawski et al reported on a dual-closed loop system that removes crosstalk artifacts in the topography channel originating from an incorrect voltage applied by the KPFM feedback loop. 28 We overcome this artifact by detecting the first-harmonic signal F ω directly in open-loop measurements; however, we note that in this case additionally the F 2ω signal has to be considered to separate transient V cpd changes from capacitive changes.…”

Section: Introductionmentioning

confidence: 99%

Nanoscale Charge Accumulation and Its Effect on Carrier Dynamics in Tri-cation Perovskite Structures

Toth

Hailegnaw

Richheimer

et al. 2020

ACS Appl. Mater. Interfaces

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Nanoscale investigations by scanning probe microscopy have provided major contributions to the rapid development of organic–inorganic halide perovskites (OIHP) as optoelectronic devices. Further improvement of device level properties requires a deeper understanding of the performance-limiting mechanisms such as ion migration, phase segregation, and their effects on charge extraction both at the nano- and macroscale. Here, we have studied the dynamic electrical response of Cs 0.05 (FA 0.83 MA 0.17 ) 0.95 PbI 3– x Br x perovskite structures by employing conventional and microsecond time-resolved open-loop Kelvin probe force microscopy (KPFM). Our results indicate strong negative charge carrier trapping upon illumination and very slow (>1 s) relaxation of charges at the grain boundaries. The fast electronic recombination and transport dynamics on the microsecond scale probed by time-resolved open-loop KPFM show diffusion of charge carriers toward grain boundaries and indicate locally higher recombination rates because of intrinsic compositional heterogeneity. The nanoscale electrostatic effects revealed are summarized in a collective model for mixed-halide CsFAMA. Results on multilayer solar cell structures draw direct relations between nanoscale ionic transport, charge accumulation, recombination properties, and the final device performance. Our findings extend the current understanding of complex charge carrier dynamics in stable multication OIHP structures.

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Artifacts in time-resolved Kelvin probe force microscopy

Cited by 10 publications

References 33 publications

Wafer‐Scale Fabrication of 2D β‐In₂Se₃ Photodetectors

Wafer‐Scale Fabrication of 2D β‐In₂Se₃ Photodetectors

Chemical instability at chalcogenide surfaces impacts chalcopyrite devices well beyond the surface

Nanoscale Charge Accumulation and Its Effect on Carrier Dynamics in Tri-cation Perovskite Structures

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Artifacts in time-resolved Kelvin probe force microscopy

Cited by 10 publications

References 33 publications

Wafer‐Scale Fabrication of 2D β‐In2Se3 Photodetectors

Wafer‐Scale Fabrication of 2D β‐In2Se3 Photodetectors

Chemical instability at chalcogenide surfaces impacts chalcopyrite devices well beyond the surface

Nanoscale Charge Accumulation and Its Effect on Carrier Dynamics in Tri-cation Perovskite Structures

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Product

Resources

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Wafer‐Scale Fabrication of 2D β‐In₂Se₃ Photodetectors

Wafer‐Scale Fabrication of 2D β‐In₂Se₃ Photodetectors