Scanning Noise Microscopy on Graphene Devices

Sung, Minki; Lee, Hyungwoo; Heo, Kwang; Byun, Kyung‐Eun; Kim, Taekyeong; Seo, David H.; Seo, Sunae; Hong, Seunghun

doi:10.1021/nn202135g

Cited by 20 publications

(18 citation statements)

References 66 publications

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“…We obtained a current-normalized noise PSD ( S I / I 2 ) map by dividing the S I values in the S I map by the corresponding current ( I ) values in the current map. The S I / I 2 value is a useful parameter to represent the noise level of an electrical channel 19 . Figure 2c shows the S I / I 2 map at 31.6 Hz.…”

Section: Resultsmentioning

confidence: 99%

Direct mapping of electrical noise sources in molecular wire-based devices

Cho

Lee

Shekhar

et al. 2017

Sci Rep

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We report a noise mapping strategy for the reliable identification and analysis of noise sources in molecular wire junctions. Here, different molecular wires were patterned on a gold substrate, and the current-noise map on the pattern was measured and analyzed, enabling the quantitative study of noise sources in the patterned molecular wires. The frequency spectra of the noise from the molecular wire junctions exhibited characteristic 1/f2 behavior, which was used to identify the electrical signals from molecular wires. This method was applied to analyze the molecular junctions comprising various thiol molecules on a gold substrate, revealing that the noise in the junctions mainly came from the fluctuation of the thiol bonds. Furthermore, we quantitatively compared the frequencies of such bond fluctuations in different molecular wire junctions and identified molecular wires with lower electrical noise, which can provide critical information for designing low-noise molecular electronic devices. Our method provides valuable insights regarding noise phenomena in molecular wires and can be a powerful tool for the development of molecular electronic devices.

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Section: Resultsmentioning

confidence: 99%

Direct mapping of electrical noise sources in molecular wire-based devices

Cho

Lee

Shekhar

et al. 2017

Sci Rep

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“…However, it has been very difficult to identify and map the activities of such localized noise−sources in a RGO film at a nanoscale resolution. Recently, we have developed a scanning noise imaging method [18][19][20]27], allowing us to map the localized noise−sources in domains and boundaries of graphene [20] and polymers [19]. Noise−source mappings further helped us in understanding transport mechanisms in conducting channels.…”

Section: Introductionmentioning

confidence: 99%

Nanoscale mapping of noise-source-controlled hopping and tunneling conduction in domains of reduced graphene oxide

Shekhar

Lee

Cho

et al. 2019

Carbon

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et al.. Nanoscale mapping of noise-source-controlled hopping and tunneling conduction in domains of reduced graphene oxide. Carbon, Elsevier, 2019, 148, pp. ABSTRACTWe report a nanoscale mapping of noise-source-controlled transport characteristics in the domains of reduced graphene oxide by utilizing noise-source imaging strategies. In this method, current and noise images were measured simultaneously using a scanning noise microscopy and analyzed to map sheet−resistances (R ) and noise−source densities (n eff ). The maps showed the formation of conducting and insulating domains, where the insulating domains exhibited up to three-four orders of higher R and n eff than those of conducting domains. Interestingly, the sheet−conductance (Σ ) and n eff followed rather opposite power−law behaviors like Σ ∝ n eff −0.5 and Σ ∝ n eff 0.5 in conducting and insulating domains, respectively, which could be attributed to the difference in mesoscopic charge transport mechanisms controlled by n eff in domains. Notably, high biases resulted in the increased conductance (∆Σ ) and decreased noise−source density (∆n eff ) following a relationship like ∆Σ ∝−∆n eff 0.5 for both conducting and insulting domains, which could be explained by the passivation of noise−sources at high biases. Furthermore, ∆Σ versus ∆n eff plot on the annealing also followed a power−law dependence (∆Σ ∝−∆n eff 0.5 ) in conducting domains, which could be attributed to carrier generation on the annealing. Our results about mesoscopic charge transports could be significant advancements in fundamental researches and applications.

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“…34 Combined with a high-spatial-resolution electronic measurement method by cAFM, noise spectroscopy can be an effective tool to characterize localized noise sources (or defects) in electronic channels. 35 However, despite its useful outcomes with a simple method, noise spectroscopy has not been widely used in the field of perovskite solar cells yet.…”

Section: ■ Introductionmentioning

confidence: 99%

Evaluating the Optoelectronic Quality of Hybrid Perovskites by Conductive Atomic Force Microscopy with Noise Spectroscopy

Lee¹,

Lee²,

Cho³

et al. 2016

ACS Appl. Mater. Interfaces

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Organic-inorganic hybrid perovskite solar cells have emerged as promising candidates for next-generation solar cells. To attain high photovoltaic efficiency, reducing the defects in perovskites is crucial along with a uniform coating of the films. Also, evaluating the quality of synthesized perovskites via facile and adequate methods is important as well. Herein, CHNHPbI perovskites were synthesized by applying second solvent dripping to nonstoichiometric precursors containing excess CHNHI. The resulting perovskite films exhibited a larger average grain size with a better crystallinity compared to that from stoichiometric precursors. As a result, the performance of planar perovskite solar cells was significantly improved, achieving an efficiency of 14.3%. Furthermore, perovskite films were effectively analyzed using a conductive AFM and noise spectroscopy, which have been uncommon in the field of perovskite solar cells. Comparing the topography and photocurrent maps, the variation of photocurrents in nanoscale was systematically investigated, and a linear relationship between the grain size and photocurrent was revealed. Also, noise analyses with a conductive probe enabled examination of the defect density of perovskites at specific grain interiors by excluding the grain-boundary effect, and reduced defects were clearly observed for the perovskites using CHNHI-rich precursors.

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Scanning Noise Microscopy on Graphene Devices

Cited by 20 publications

References 66 publications

Direct mapping of electrical noise sources in molecular wire-based devices

Direct mapping of electrical noise sources in molecular wire-based devices

Nanoscale mapping of noise-source-controlled hopping and tunneling conduction in domains of reduced graphene oxide

Evaluating the Optoelectronic Quality of Hybrid Perovskites by Conductive Atomic Force Microscopy with Noise Spectroscopy

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