Strain‐Engineering of Contact Energy Barriers and Photoresponse Behaviors in Monolayer MoS<sub>2</sub> Flexible Devices

Pak, Sangyeon; Lee, Juwon; Jang, A‐Rang; Kim, Seungje; Park, Kyung‐Ho; Sohn, Jung Inn; Cha, SeungNam

doi:10.1002/adfm.202002023

Cited by 73 publications

(56 citation statements)

References 42 publications

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“…Along with the changes in the dark current, the photocurrent was increased as the bending radius decreases down to 3.5 mm. Such trend observed for the flexible MoS 2 /CuS photodetector under bending strain is consistent with the previous report showing piezoresistive effect, [43] where the contact barrier height is reduced due to the changes in the electron affinity under the applied tensile strain and the corresponding photo-electrical properties are improved due to the reduced contact barriers.…”

Section: Resultssupporting

confidence: 92%

Electrode‐Induced Self‐Healed Monolayer MoS₂ for High Performance Transistors and Phototransistors

et al. 2021

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transparent, and wearable electronics and optoelectronics due to their reduced dimensions that offer flexibility and transparency with proper band gap, high carrier mobility, and highly efficient light absorption. [1][2][3] In addition, their ideally dangling-bond-free surface and atomic thickness are promising for ideal heterogeneous contact and reduced short channel effect, [4] thus making them suitable for future nano-scaled electronic and optoelectronic devices. An ideal field-effect transistor based on an molybdenum disulfide (MoS 2 ) channel is theoretically predicted to reach large on/off ratio (>10 9 ), room temperature mobility of 410 cm 2 (Vs) −1 , and near-ideal subthreshold swing of 60 meV per decade. [5,6] However, most of experimental results significantly differ from the aforementioned theoretical predictions. One of dominant factors degrading the overall performance of 2D materials based devices arises from unwanted chemical interactions between deposited metal electrodes and 2D TMDC channel. These chemical interactions originate from incomplete/imperfect covalent/surface bonds of TMDCs and unwanted damages from the direct deposition of metal layers and precursors, which are used during the device fabrication processes. These lead to the creation of unfavorable interface states and pinning of fermi energy levels, which Contact engineering for monolayered transition metal dichalcogenides (TMDCs) is considered to be of fundamental challenge for realizing highperformance TMDCs-based (opto) electronic devices. Here, an innovative concept is established for a device configuration with metallic copper monosulfide (CuS) electrodes that induces sulfur vacancy healing in the monolayer molybdenum disulfide (MoS 2 ) channel. Excess sulfur adatoms from the metallic CuS electrodes are donated to heal sulfur vacancy defects in MoS 2 that surprisingly improve the overall performance of its devices. The electrode-induced self-healing mechanism is demonstrated and analyzed systematically using various spectroscopic analyses, density functional theory (DFT) calculations, and electrical measurements. Without any passivation layers, the self-healed MoS 2 (photo)transistor with the CuS contact electrodes show outstanding room temperature field effect mobility of 97.6 cm 2 (Vs) −1 , On/Off ratio > 10 8 , low subthreshold swing of 120 mV per decade, high photoresponsivity of 1 × 10 4 A W −1 , and detectivity of 10 13 jones, which are the best among back-gated transistors that employ 1L MoS 2 . Using ultrathin and flexible 2D CuS and MoS 2 , mechanically flexible photosensor is also demonstrated, which shows excellent durability under mechanical strain. These findings demonstrate a promising strategy in TMDCs or other 2D material for the development of high performance and functional devices including self-healable sulfide electrodes.

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Section: Resultssupporting

confidence: 92%

Electrode‐Induced Self‐Healed Monolayer MoS₂ for High Performance Transistors and Phototransistors

et al. 2021

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“…Controlling the energy level MoS2 can activate or deactivate the electrochemical HER kinetics by the surface functio alization of the MoS2 monolayer [5,14]. Furthermore, as evidenced in the output curve Figure S3, the rise in Fermi level decreased the potential barrier between the electrode a the MoS2 catalyst, which facilitated the charge injection from the electrode to the MoS2 a resulted in enhanced catalytic activities of the MoS2 monolayer [14,27]. Thus, the increa in the carrier density and the corresponding Fermi level accelerate the HER kinetics a must be considered when designing the catalysts based on 2D semiconductors.…”

Section: Resultsmentioning

confidence: 99%

Enhanced Hydrogen Evolution Reaction in Surface Functionalized MoS2 Monolayers

et al. 2021

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Monolayered, semiconducting MoS2 and their transition metal dichalcogenides (TMDCs) families are promising and low-cost materials for hydrogen generation through electrolytes (HER, hydrogen evolution reaction) due to their high activities and electrochemical stability during the reaction. However, there is still a lack of understanding in identifying the underlying mechanism responsible for improving the electrocatalytic properties of theses monolayers. In this work, we investigated the significance of controlling carrier densities in a MoS2 monolayer and in turn the corresponding electrocatalytic behaviors in relation to the energy band structure of MoS2. Surface functionalization was employed to achieve p-doping and n-doping in the MoS2 monolayer that led to MoS2 electrochemical devices with different catalytic performances. Specifically, the electron-rich MoS2 surface showed lower overpotential and Tafel slope compared to the MoS2 with surface functional groups that contributed to p-doping. We attributed such enhancement to the increase in the carrier density and the corresponding Fermi level that accelerated HER and charge transfer kinetics. These findings are of high importance in designing electrocatalysts based on two-dimensional TMDCs.

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“…The contact energy barrier between MoS2 and metal contacts under stretching or bending was also investigated. Pak et al fabricated two-terminal flexible MoS2 devices and studied the contact barrier by kelvin probe force microscope 1473 . The observation is that tensile strain can increase electron affinity and lower the contact barrier, which will be beneficial to the optoelectronic performance (Fig.…”

Section: Flexible Electronicsmentioning

confidence: 99%

Recent Progress on Two-Dimensional Materials

Chang¹,

Chen²,

Chen³

et al. 2021

Acta Physico Chimica Sinica

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Research on two-dimensional (2D) materials has been explosively increasing in last seventeen years in varying subjects including condensed matter physics, electronic engineering, materials science, and chemistry since the mechanical exfoliation of graphene in 2004. Starting from graphene, 2D materials now have become a big family with numerous members and diverse categories. The unique structural features and physicochemical properties of 2D materials make them one class of the most appealing candidates for a wide range of potential applications.In particular, we have seen some major breakthroughs made in the field of 2D materials in last five years not only in developing novel synthetic methods and exploring new structures/properties but also in identifying innovative applications and pushing forward commercialisation. In this review, we provide a critical summary on the recent progress made in the field of 2D materials with a particular focus on last five years. After a brief background 物理化学学报 Acta Phys. -Chim. Sin. 2021, 37 (12), 2108017 (3 of 151) introduction, we first discuss the major synthetic methods for 2D materials, including the mechanical exfoliation, liquid exfoliation, vapor phase deposition, and wet-chemical synthesis as well as phase engineering of 2D materials belonging to the field of phase engineering of nanomaterials (PEN). We then introduce the superconducting/optical/magnetic properties and chirality of 2D materials along with newly emerging magic angle 2D superlattices. Following that, the promising applications of 2D materials in electronics, optoelectronics, catalysis, energy storage, solar cells, biomedicine, sensors, environments, etc. are described sequentially. Thereafter, we present the theoretic calculations and simulations of 2D materials. Finally, after concluding the current progress, we provide some personal discussions on the existing challenges and future outlooks in this rapidly developing field.

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Strain‐Engineering of Contact Energy Barriers and Photoresponse Behaviors in Monolayer MoS₂ Flexible Devices

Cited by 73 publications

References 42 publications

Electrode‐Induced Self‐Healed Monolayer MoS₂ for High Performance Transistors and Phototransistors

Electrode‐Induced Self‐Healed Monolayer MoS₂ for High Performance Transistors and Phototransistors

Enhanced Hydrogen Evolution Reaction in Surface Functionalized MoS2 Monolayers

Recent Progress on Two-Dimensional Materials

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Strain‐Engineering of Contact Energy Barriers and Photoresponse Behaviors in Monolayer MoS2 Flexible Devices

Cited by 73 publications

References 42 publications

Electrode‐Induced Self‐Healed Monolayer MoS2 for High Performance Transistors and Phototransistors

Electrode‐Induced Self‐Healed Monolayer MoS2 for High Performance Transistors and Phototransistors

Enhanced Hydrogen Evolution Reaction in Surface Functionalized MoS2 Monolayers

Recent Progress on Two-Dimensional Materials

Contact Info

Product

Resources

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Strain‐Engineering of Contact Energy Barriers and Photoresponse Behaviors in Monolayer MoS₂ Flexible Devices

Electrode‐Induced Self‐Healed Monolayer MoS₂ for High Performance Transistors and Phototransistors

Electrode‐Induced Self‐Healed Monolayer MoS₂ for High Performance Transistors and Phototransistors