Competing Mechanisms for Photocurrent Induced at the Monolayer–Multilayer Graphene Junction

Zhang, Youwei; Zheng, Hemei; Wang, Qiyuan; Cong, Chunxiao; Hu, Laigui; Tian, Pengfei; Liu, Ran; Zhang, Shi-Li; Qiu, Zhijun

doi:10.1002/smll.201800691

Cited by 14 publications

(15 citation statements)

References 57 publications

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“…To visualize the spatial-resolved photoresponse of the device, SPCM was performed at the zero source–drain voltage ( V ds = 0 V) with low-power 633 nm laser scanning over the device, as illustrated in Figure a,b. SPCM has been previously employed to investigate the photoelectric and electrical properties of many 2D materials, such as graphene − and layered TMDCs. , Figure c,d shows the photocurrent images of the pristine WSe 2 FET measured at V g = ±40 V. We observed two photocurrent maxima with opposite polarities appearing at the edges of the contact electrodes, where lateral electric fields were created by Schottky junctions. In contrast, only one localized photocurrent response was observed for the partially p-doped WSe 2 FET at both positive and negative V g (Figure e,f).…”

Section: Resultsmentioning

confidence: 87%

High-Performance WSe₂ Photodetector Based on a Laser-Induced p–n Junction

Chen

Wang

Sheng

et al. 2019

ACS Appl. Mater. Interfaces

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Two-dimensional heterojunctions exhibit many unique features in nanoelectronic and optoelectronic devices. However, heterojunction engineering requires a complicated alignment process and some defects are inevitably introduced during material preparation. In this work, a laser scanning technique is used to construct a lateral WSe2 p–n junction. The laser-scanned region shows p-type behavior, and the adjacent region is electrically n-doped with a proper gate voltage. The laser-oxidized product WO x is found to be responsible for this p-type doping. After laser scanning, WSe2 displays a change from ambipolar to unipolar p-type property. A significant photocurrent emerges at the p–n junction. Therefore, a self-powered WSe2 photodetector can be fabricated based on this junction, which presents a large photoswitching ratio of 106, a high photoresponsivity of 800 mA W–1, and a short photoresponse time with long-term stability and reproducibility. Therefore, this selective laser-doping method is prospective in future electronic applications.

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Section: Resultsmentioning

confidence: 87%

High-Performance WSe₂ Photodetector Based on a Laser-Induced p–n Junction

Chen

Wang

Sheng

et al. 2019

ACS Appl. Mater. Interfaces

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“…Consequently, this limits the energy dissipation for photo-excited carriers, creating a population of electrons with a large effective temperature. Although PTE has been shown to dominate in graphene junctions devices, the presence of photovoltaic (PV) effects cannot be excluded, as it has been recently reported in single/multi-layer graphene junctions [ 56 ].…”

Section: Light Detection In Graphene-based Devicesmentioning

confidence: 99%

Graphene-Based Light Sensing: Fabrication, Characterisation, Physical Properties and Performance

et al. 2018

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Graphene and graphene-based materials exhibit exceptional optical and electrical properties with great promise for novel applications in light detection. However, several challenges prevent the full exploitation of these properties in commercial devices. Such challenges include the limited linear dynamic range (LDR) of graphene-based photodetectors, the lack of efficient generation and extraction of photoexcited charges, the smearing of photoactive junctions due to hot-carriers effects, large-scale fabrication and ultimately the environmental stability of the constituent materials. In order to overcome the aforementioned limits, different approaches to tune the properties of graphene have been explored. A new class of graphene-based devices has emerged where chemical functionalisation, hybridisation with light-sensitising materials and the formation of heterostructures with other 2D materials have led to improved performance, stability or versatility. For example, intercalation of graphene with FeCl3 is highly stable in ambient conditions and can be used to define photo-active junctions characterized by an unprecedented LDR while graphene oxide (GO) is a very scalable and versatile material which supports the photodetection from UV to THz frequencies. Nanoparticles and quantum dots have been used to enhance the absorption of pristine graphene and to enable high gain thanks to the photogating effect. In the same way, hybrid detectors made from stacked sequences of graphene and layered transition-metal dichalcogenides enabled a class of devices with high gain and responsivity. In this work, we will review the performance and advances in functionalised graphene and hybrid photodetectors, with particular focus on the physical mechanisms governing the photoresponse, the performance and possible future paths of investigation.

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“…PVE can also dominate photocurrent in the junction, which is consistent with the built-in electric field all along. Zhang et al found that the dominant mechanism depended on the separation of a Dirac point for both side graphene [180]. They fabricated a monolayer/multilayer graphene junction and acquired its photocurrent mapping, as shown in Fig.…”

Section: Scanning Photocurrent Microscopymentioning

confidence: 99%

Recent progress and challenges on two-dimensional material photodetectors from the perspective of advanced characterization technologies

Zhong

Wang

et al. 2020

Nano Res.

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Atomically thin two-dimensional (2D) materials exhibit enormous potential in photodetectors because of novel and extraordinary properties, such as passivated surfaces, tunable bandgaps, and high mobility. High-performance photodetectors based on 2D materials have been fabricated for broadband, position, polarization-sensitive detection, and large-area array imaging. However, the current performance of 2D material photodetectors is not outstanding enough, including response speed, detectivity, and so forth. The way to further promote the development of 2D material photodetectors and their corresponding practical applications is still a tremendous challenge. In this article, these issues of 2D material photodetectors are analyzed and expected to be solved by combining micro-nano characterization technologies. The inherent physical properties of 2D materials and photodetectors can be accurately characterized by Raman spectroscopy, transmission electron microscopy (TEM), and scattering scanning near-field optical microscope (s-SNOM). In particular, the precise probe of lattice defects, doping concentration, and near-field light absorption characteristics can promote the researches of low-noise and high-responsivity photodetectors. Scanning photocurrent microscope (SPCM) can show the overall spatial distribution of photocurrent and analyze the mechanism of photocurrent. Photoluminescence (PL) spectroscopy and Kelvin probe force microscope (KPFM) can characterize the material bandgap, work function distribution and interlayer coupling characteristics, making it possible to design high-performance photodetectors through energy band engineering. These advanced characterization techniques cover the entire process from material growth, to device preparation, and to performance analysis, and systematically reveal the development status of 2D material photodetectors. Finally, the prospects and challenges are discussed to promote the application of 2D material photodetectors.

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Competing Mechanisms for Photocurrent Induced at the Monolayer–Multilayer Graphene Junction

Cited by 14 publications

References 57 publications

High-Performance WSe₂ Photodetector Based on a Laser-Induced p–n Junction

High-Performance WSe₂ Photodetector Based on a Laser-Induced p–n Junction

Graphene-Based Light Sensing: Fabrication, Characterisation, Physical Properties and Performance

Recent progress and challenges on two-dimensional material photodetectors from the perspective of advanced characterization technologies

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Competing Mechanisms for Photocurrent Induced at the Monolayer–Multilayer Graphene Junction

Cited by 14 publications

References 57 publications

High-Performance WSe2 Photodetector Based on a Laser-Induced p–n Junction

High-Performance WSe2 Photodetector Based on a Laser-Induced p–n Junction

Graphene-Based Light Sensing: Fabrication, Characterisation, Physical Properties and Performance

Recent progress and challenges on two-dimensional material photodetectors from the perspective of advanced characterization technologies

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Product

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High-Performance WSe₂ Photodetector Based on a Laser-Induced p–n Junction

High-Performance WSe₂ Photodetector Based on a Laser-Induced p–n Junction