Efficient MoWO3/VO2/MoS2/Si UV Schottky photodetectors; MoS2 optimization and monoclinic VO2 surface modifications

Abstract The distinctive properties of strongly correlated oxides provide a variety of possibilities for modulating the properties of 2D transition metal dichalcogenides semiconductors; which represent a new class of superior optical and optoelectronic interfacing semiconductors. We report a novel approach to scaling-up molybdenum disulfide (MoS2) by combining the techniques of chemical and physical vapor deposition (CVD and PVD) and interfacing with a thin layer of monoclinic VO2. MoWO3/VO2/MoS2 photodetectors were manufactured at different sputtering times by depositing molybdenum oxide layers using a PVD technique on p-type silicon substrates followed by a sulphurization process in the CVD chamber. The high quality and the excellent structural and absorption properties of MoWO3/VO2/MoS2/Si with MoS2 deposited for 60 s enables its use as an efficient UV photodetector. The electronically coupled monoclinic VO2 layer on MoS2/Si causes a redshift and intensive MoS2 Raman peaks. Interestingly, the incorporation of VO2 dramatically changes the ratio between A-exciton (ground state exciton) and trion photoluminescence intensities of VO2/(30 s)MoS2/Si from < 1 to > 1. By increasing the deposition time of MoS2 from 60 to 180 s, the relative intensity of the B-exciton/A-exciton increases, whereas the lowest ratio at deposition time of 60 s refers to the high quality and low defect densities of the VO2/(60 s)MoS2/Si structure. Both the VO2/(60 s)MoS2/Si trion and A-exciton peaks have higher intensities compared with (60 s) MoS2/Si structure. The MoWO3/VO2/(60 s)MoS2/Si photodetector displays the highest photocurrent gain of 1.6, 4.32 × 108 Jones detectivity, and ~ 1.0 × 1010 quantum efficiency at 365 nm. Moreover, the surface roughness and grains mapping are studied and a low semiconducting-metallic phase transition is observed at ~ 40 °C.

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Methane-Mediated Vapor Transport Growth of Monolayer WSe2 Crystals

Nanomaterials ◽

10.3390/nano9111642 ◽

2019 ◽

Vol 9 (11) ◽

pp. 1642

Author(s):

Hyeon-Sik Jang ◽

Jae-Young Lim ◽

Seog-Gyun Kang ◽

Sang-Hwa Hyun ◽

Sana Sandhu ◽

...

Keyword(s):

Optical Properties ◽

Transition Metal Dichalcogenides ◽

Nucleation Density ◽

Large Area ◽

High Quality ◽

Catalytic Growth ◽

Production Methods ◽

Metal Dichalcogenides ◽

Device Applications ◽

P Type

The electrical and optical properties of semiconducting transition metal dichalcogenides (TMDs) can be tuned by controlling their composition and the number of layers they have. Among various TMDs, the monolayer WSe2 has a direct bandgap of 1.65 eV and exhibits p-type or bipolar behavior, depending on the type of contact metal. Despite these promising properties, a lack of efficient large-area production methods for high-quality, uniform WSe2 hinders its practical device applications. Various methods have been investigated for the synthesis of large-area monolayer WSe2, but the difficulty of precisely controlling solid-state TMD precursors (WO3, MoO3, Se, and S powders) is a major obstacle to the synthesis of uniform TMD layers. In this work, we outline our success in growing large-area, high-quality, monolayered WSe2 by utilizing methane (CH4) gas with precisely controlled pressure as a promoter. When compared to the catalytic growth of monolayered WSe2 without a gas-phase promoter, the catalytic growth of the monolayered WSe2 with a CH4 promoter reduced the nucleation density to 1/1000 and increased the grain size of monolayer WSe2 up to 100 μm. The significant improvement in the optical properties of the resulting WSe2 indicates that CH4 is a suitable candidate as a promoter for the synthesis of TMD materials, because it allows accurate gas control.

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Melt Blown Fiber-Assisted Solvent-Free Device Fabrication at Low-Temperature

Micromachines ◽

10.3390/mi11121091 ◽

2020 ◽

Vol 11 (12) ◽

pp. 1091

Author(s):

Minjong Lee ◽

Joohoon Kang ◽

Young Tack Lee

Keyword(s):

Transition Metal Dichalcogenides ◽

Hole Mobility ◽

Device Fabrication ◽

Solvent Free ◽

Oxide Semiconductor ◽

Drain Voltage ◽

Cmos Inverter ◽

Current Ratio ◽

Metal Dichalcogenides ◽

P Type

In this paper, we propose a solvent-free device fabrication method using a melt-blown (MB) fiber to minimize potential chemical and thermal damages to transition-metal-dichalcogenides (TMDCs)-based semiconductor channel. The fabrication process is composed of three steps; (1) MB fibers alignment as a shadow mask, (2) metal deposition, and (3) lifting-up MB fibers. The resulting WSe2-based p-type metal-oxide-semiconductor (PMOS) device shows an ON/OFF current ratio of ~2 × 105 (ON current of ~−40 µA) and a remarkable linear hole mobility of ~205 cm2/V·s at a drain voltage of −0.1 V. These results can be a strong evidence supporting that this MB fiber-assisted device fabrication can effectively suppress materials damage by minimizing chemical and thermal exposures. Followed by an MoS2-based n-type MOS (NMOS) device demonstration, a complementary MOS (CMOS) inverter circuit application was successfully implemented, consisted of an MoS2 NMOS and a WSe2 PMOS as a load and a driver transistor, respectively. This MB fiber-based device fabrication can be a promising method for future electronics based on chemically reactive or thermally vulnerable materials.

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Hole doping effect of MoS2 via electron capture of He+ ion irradiation

Scientific Reports ◽

10.1038/s41598-021-02932-6 ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Sang Wook Han ◽

Won Seok Yun ◽

Hyesun Kim ◽

Yanghee Kim ◽

D.-H. Kim ◽

...

Keyword(s):

Electron Capture ◽

Ion Irradiation ◽

Noble Gas ◽

Transition Metal Dichalcogenides ◽

General Purpose ◽

Low Energy ◽

Hole Doping ◽

Universal Method ◽

Metal Dichalcogenides ◽

P Type

AbstractBeyond the general purpose of noble gas ion sputtering, which is to achieve functional defect engineering of two-dimensional (2D) materials, we herein report another positive effect of low-energy (100 eV) He+ ion irradiation: converting n-type MoS2 to p-type by electron capture through the migration of the topmost S atoms. The electron capture ability via He+ ion irradiation is valid for supported bilayer MoS2; however, it is limited at supported monolayer MoS2 because the charges on the underlying substrates transfer into the monolayer under the current condition for He+ ion irradiation. Our technique provides a stable and universal method for converting n-type 2D transition metal dichalcogenides (TMDs) into p-type semiconductors in a controlled fashion using low-energy He+ ion irradiation.

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Electrical and optical properties of transition metal dichalcogenides on talc dielectrics

Nanoscale ◽

10.1039/d1nr04723j ◽

2021 ◽

Author(s):

Darren Nutting ◽

Gabriela Augusta Prando ◽

Marion Severijnen ◽

Ingrid Barcelos ◽

Shi Guo ◽

...

Keyword(s):

Optical Properties ◽

Transition Metal ◽

Defect Density ◽

Transition Metal Dichalcogenides ◽

Dielectric Materials ◽

High Quality ◽

Electrical And Optical Properties ◽

Metal Dichalcogenides ◽

Vdw Heterostructure ◽

Heterostructure Devices

Advanced van der Waals (vdW) heterostructure devices rely on the incorporation of high quality dielectric materials which need to possess a low defect density as well as being atomically smooth...

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Wafer scale synthesis of organic semiconductor nanosheets for van der Waals heterojunction devices

npj 2D Materials and Applications ◽

10.1038/s41699-021-00270-9 ◽

2021 ◽

Vol 5 (1) ◽

Author(s):

Sirri Batuhan Kalkan ◽

Emad Najafidehaghani ◽

Ziyang Gan ◽

Fabian Alexander Christian Apfelbeck ◽

Uwe Hübner ◽

...

Keyword(s):

Organic Semiconductors ◽

Physical Vapor Deposition ◽

Field Effect Transistors ◽

Van Der Waals ◽

Transition Metal Dichalcogenides ◽

Wafer Scale ◽

Heterojunction Devices ◽

Wide Range ◽

Conformal Electronics ◽

Metal Dichalcogenides

AbstractOrganic semiconductors (OSC) are widely used for consumer electronic products owing to their attractive properties such as flexibility and low production cost. Atomically thin transition metal dichalcogenides (TMDs) are another class of emerging materials with superior electronic and optical properties. Integrating them into van der Waals (vdW) heterostructures provides an opportunity to harness the advantages of both material systems. However, building such heterojunctions by conventional physical vapor deposition (PVD) of OSCs is challenging, since the growth is disrupted due to limited diffusion of the molecules on the TMD surface. Here we report wafer-scale (3-inch) fabrication of transferable OSC nanosheets with thickness down to 15 nm, which enable the realization of heterojunction devices. By controlled dissolution of a poly(acrylic acid) film, on which the OSC films were grown by PVD, they can be released and transferred onto arbitrary substrates. OSC crystal quality and optical anisotropy are preserved during the transfer process. By transferring OSC nanosheets (p-type) onto prefabricated electrodes and TMD monolayers (n-type), we fabricate and characterize various electronic devices including unipolar, ambipolar and antiambipolar field-effect transistors. Such vdW p-n heterojunction devices open up a wide range of possible applications ranging from ultrafast photodetectors to conformal electronics.

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High hole mobility in physical vapour deposition-grown tellurium-based transistors

Royal Society Open Science ◽

10.1098/rsos.210554 ◽

2021 ◽

Vol 8 (8) ◽

pp. 210554

Author(s):

Lin Tao ◽

Lixiang Han ◽

Qian Yue ◽

Bin Yao ◽

Yujue Yang ◽

...

Keyword(s):

High Performance ◽

Carrier Mobility ◽

Vapour Deposition ◽

Field Effect Transistors ◽

Transition Metal Dichalcogenides ◽

High Mobility ◽

Hole Mobility ◽

Physical Vapour Deposition ◽

Metal Dichalcogenides ◽

P Type

Carrier mobility is one of most important figures of merit for materials that can determine to a large extent the corresponding device performances. So far, extensive efforts have been devoted to the mobility improvement of two-dimensional (2D) materials regarded as promising candidates to complement the conventional semiconductors. Graphene has amazing mobility but suffers from zero bandgap. Subsequently, 2D transition-metal dichalcogenides benefit from their sizable bandgap while the mobility is limited. Recently, the 2D elemental materials such as the representative black phosphorus can combine the high mobility with moderate bandgap; however the air-stability is a challenge. Here, we report air-stable tellurium flakes and wires using the facile and scalable physical vapour deposition (PVD) method. The prototype field-effect transistors were fabricated to exhibit high hole mobility up to 1485 cm 2 V −1 s −1 at room temperature and 3500 cm 2 V −1 s −1 at low temperature (2 K). This work can attract numerous attentions on this new emerging 2D tellurium and open up a new way for exploring high-performance optoelectronics based on the PVD-grown p-type tellurium.

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Longitudinal unzipping of 2D transition metal dichalcogenides

Nature Communications ◽

10.1038/s41467-020-18810-0 ◽

2020 ◽

Vol 11 (1) ◽

Author(s):

Suchithra Padmajan Sasikala ◽

Yashpal Singh ◽

Li Bing ◽

Taeyoung Yun ◽

Sung Hwan Koo ◽

...

Keyword(s):

Transition Metal ◽

Transition Metal Dichalcogenides ◽

Metallic Phase ◽

Pt Catalyst ◽

Metal Chalcogenides ◽

Geometric Transformations ◽

Material Chemistry ◽

Water Edge ◽

Metal Dichalcogenides ◽

Elemental Nature

Abstract Unzipping of the basal plane offers a valuable pathway to uniquely control the material chemistry of 2D structures. Nonetheless, reliable unzipping has been reported only for graphene and phosphorene thus far. The single elemental nature of those materials allows a straightforward understanding of the chemical reaction and property modulation involved with such geometric transformations. Here we report spontaneous linear ordered unzipping of bi-elemental 2D MX2 transition metal chalcogenides as a general route to synthesize 1D nanoribbon structures. The strained metallic phase (1T′) of MX2 undergoes highly specific longitudinal unzipping owing to the self-linearized oxygenation at chalcogenides. Stable dispersions of 1T′ MoS2 nanoribbons with widths of 10–120 nm and lengths up to ~4 µm are produced in water. Edge abundant 1T′ MoS2 nanoribbons reveal the hidden potential of idealized electrocatalysis for hydrogen evolution reactions at a competitive level with the precious Pt catalyst.

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Precise Layer Control of MoTe2 by Ozone Treatment

Nanomaterials ◽

10.3390/nano9050756 ◽

2019 ◽

Vol 9 (5) ◽

pp. 756 ◽

Cited By ~ 3

Author(s):

Qiyuan Wang ◽

Jing Chen ◽

Youwei Zhang ◽

Laigui Hu ◽

Ran Liu ◽

...

Keyword(s):

Transition Metal Dichalcogenides ◽

Atomic Scale ◽

Ozone Treatment ◽

Layer By Layer ◽

Precise Control ◽

Metal Dichalcogenides ◽

Multiple Cycles ◽

P Type ◽

Device Properties ◽

Layer Control

Transition metal dichalcogenides (TMDCs) demonstrate great potential in numerous applications. However, these applications require a precise control of layer thickness at the atomic scale. In this work, we present an in-situ study of the self-limiting oxidation process in MoTe2 by ozone (O3) treatment. A precise layer-by-layer control of MoTe2 flakes can be achieved via multiple cycles of oxidation and wet etching. The thinned MoTe2 flakes exhibit comparable optical properties and film quality to the pristine exfoliated ones. Besides, an additional p-type doping is observed after O3 oxidation. Such a p-doping effect converts the device properties of MoTe2 from electron-dominated to hole-dominated ambipolar characteristics.

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Photoelectric Characteristics of a Large-Area n-MoS2/p-Si Heterojunction Structure Formed through Sulfurization Process

Sensors ◽

10.3390/s20247340 ◽

2020 ◽

Vol 20 (24) ◽

pp. 7340

Author(s):

Yoonsok Kim ◽

Taeyoung Kim ◽

Eun Kyu Kim

Keyword(s):

Near Infrared ◽

2D Materials ◽

Transition Metal Dichalcogenides ◽

Large Area ◽

Heterojunction Structure ◽

Sulfurization Process ◽

Decay Times ◽

Materials Research ◽

Metal Dichalcogenides ◽

P Type

Two-dimensional (2D) materials, such as molybdenum disulfide (MoS2) of the transition metal dichalcogenides family, are widely investigated because of their outstanding electrical and optical properties. However, not much of the 2D materials research completed to date has covered large-area structures comprised of high-quality heterojunction diodes. We fabricated a large-area n-MoS2/p-Si heterojunction structure by sulfurization of MoOx film, which is thermally evaporated on p-type silicon substrate. The n-MoS2/p-Si structure possessed excellent diode characteristics such as ideality factor of 1.53 and rectification ratio in excess of 104. Photoresponsivity and detectivity of the diode showed up to 475 mA/W and 6.5 × 1011 Jones, respectively, in wavelength ranges from visible to near-infrared. The device appeared also the maximum external quantum efficiency of 72%. The rise and decay times of optical transient response were measured about 19.78 ms and 0.99 ms, respectively. These results suggest that the sulfurization process for large-area 2D heterojunction with MoS2 can be applicable to next-generation electronic and optoelectronic devices.

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Pulsed Laser Deposition of Transition Metal Dichalcogenides-Based Heterostructures for Efficient Photodetection

10.5772/intechopen.94236 ◽

2020 ◽

Author(s):

Deependra Kumar Singh ◽

Karuna Kar Nanda ◽

Saluru Baba Krupanidhi

Keyword(s):

Transition Metal ◽

Pulsed Laser Deposition ◽

Physical Vapor Deposition ◽

Semiconductor Industry ◽

Transition Metal Dichalcogenides ◽

Pulsed Laser ◽

Laser Deposition ◽

Great Promise ◽

Large Area ◽

Metal Dichalcogenides

From the past few decades, photodetectors (PDs) are being regarded as crucial components of many photonic devices which are being used in various important applications. However, the PDs based on the traditional bulk semiconductors still face a lot of challenges as far as the device performance is concerned. To overcome these limitations, a novel class of two-dimensional materials known as transition metal dichalcogenides (TMDCs) has shown great promise. The TMDCs-based PDs have been reported to exhibit competitive figures of merit to the state-of-the-art PDs, however, their production is still limited to laboratory scale due to limitations in the conventional fabrication methods. Compared to these traditional synthesis approaches, the technique of pulsed laser deposition (PLD) offers several merits. PLD is a physical vapor deposition approach, which is performed in an ultrahigh-vacuum environment. Therefore, the products are expected to be clean and free from contaminants. Most importantly, PLD enables actualization of large-area thin films, which can have a significant potential in the modern semiconductor industry. In the current chapter, the growth of TMDCs by PLD for applications in photodetection has been discussed, with a detailed analysis on the recent advancements in this area. The chapter will be concluded by providing an outlook and perspective on the strategies to overcome the shortcomings associated with the current devices.

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