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Emerging Two-dimensional Transition Metal Dichalcogenides : = Growth, Light-matter Interactions and Devices.

紀錄類型:	書目-電子資源 : Monograph/item
正題名/作者:	Emerging Two-dimensional Transition Metal Dichalcogenides :/
其他題名:	Growth, Light-matter Interactions and Devices.
作者:	Tao, Li.
面頁冊數:	1 online resource (189 pages)
附註:	Source: Dissertations Abstracts International, Volume: 80-08, Section: B.
Contained By:	Dissertations Abstracts International80-08B.
標題:	Electrical engineering. -
電子資源:	http://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=13837774click for full text (PQDT)
ISBN:	9780438850729

Emerging Two-dimensional Transition Metal Dichalcogenides : = Growth, Light-matter Interactions and Devices.
Tao, Li.

Emerging Two-dimensional Transition Metal Dichalcogenides :Growth, Light-matter Interactions and Devices. - 1 online resource (189 pages)

Source: Dissertations Abstracts International, Volume: 80-08, Section: B.

Thesis (Ph.D.)--The Chinese University of Hong Kong (Hong Kong), 2018.

Includes bibliographical references

The interface of a material is crucial for its physical properties and device applications as stated by Herbert Kroemer "The interface is the device." Two-dimensional layered materials (2DLMs), which consist of single or a few atomic layers, have recently emerged as rising stars in material research due to the fascinating all-surface nature, with diverse electronic properties ranging from semimetals (e.g., graphene and 1T'-MoTe 2) and semiconductors (2H-MoS2 and black phosphorus) to insulators (e.g., hexagonal boron nitride). By incorporating various 2DLMs, researchers have enormous amounts of opportunities for building intriguing electronic/optoelectronic devices and sensors with properties very different from their bulk counterparts. However, it has still been technically challenging to realize controllable large-area fabrication of 2DLMs, reliable transfer for building heterostructures, and to achieve promising performance in optoelectronic device and sensors. First part of the thesis presents a facile chemical vapor deposition (CVD) method with solution-processed precursors and rate-controlled gas flow to grow large-scale and uniform transition metal dichalcogenides (TMDCs) based on. The as-grown centimeter-scale MoS2 monolayer film exhibits high spatial homogeneity and the intrinsic grain boundaries can be observed by the photoluminescence (PL) mapping and atomic force microscope phase images, showing a low density of 0.04 μm-1. Electrical transport experiments showed that the carrier mobility is found to be insensitive to the channel length, confirming the high uniformity of the film. This versatile solution-processed CVD method can be also applied to multiple TMDC materials. Secondly, we have developed a green (etching-free) and deterministic transfer method for CVD-grown 2DLMs. A water-soluble viscoelastic polyvinyl alcohol (PVA) polymer has been chosen to selectively peel the 2D material off the growth substrate, with the help of the high-accuracy xyz-axis micromanipulator. The delaminated 2D material can be placed onto desired positions with highly preserved physical properties. 2D electronic devices were fabricated by transferring the material onto pre-deposited electrodes. The carrier mobilities are found to be largely enhanced, in comparison to the control devices made using the wet etching transfer. More interestingly, the efficient PL quenching and emerging Raman modes provide the evidence of the strong interlayer coupling in the stacked monolayer MoS2/WSe2 heterostructure. Taking a step further, we have fabricated the silicon sensitized graphene photodetectors with interface engineering. The photodetector delivers ultrafast response speed (17 ns rising time) with monolayer MoS2 as the passivation layer, which is three orders of magnitude improved with respect to the control device without MoS2, while the responsivity remains high. Noise analysis demonstrated that the dangling-bond-free MoS2 efficiently passivates the interface traps. On the other hand, the photodetector exhibits unconventional phototunable transfer characteristics with ultrathin Al 2O3 (3 nm) as the interface layer. The device shows off-state in the dark and on-state under illumination at high gate voltages, giving the largely enhanced photoresponse. This intriguing photo-induced switching-on behavior results from the modification of silicon depletion region under illumination. Finally, we have investigated the novel CVD-grown 1T' transition metal tellurides as potential candidates for ultrasensitive surface-enhanced Raman scattering (SERS). The plasmon-free 1T'-W(Mo)Te2 exhibits excellent SERS detectivity which is capable to probe analytes at femtomolar levels. This ultralow limit of detection far exceeds the intensively reported 2D graphene as SERS mediator, and is even comparable to the plasmon-based noble metal structures. Additionally, the molecule fluorescence signals are strongly suppressed on the 1T'-W(Mo)Te2, making the SERS peaks highly distinguishable from the backgrounds. As a chemically active and type-II Weyl semi-metallic material, the 1T'-W(Mo)Te2 generates strong interactions with the analyte and large density of states for charge transfer. Hence, the ultrasensitive SERS effect is observed due to the large charge transfer in the analyte-telluride complex that can efficiently borrow the intensity from the nearby molecular optical transition. This SERS effect can be even further enhanced with the incorporating of a Bragg reflector.

Electronic reproduction.
Ann Arbor, Mich. :
ProQuest,
2023

Mode of access: World Wide Web

ISBN: 9780438850729Subjects--Topical Terms:

649834
Electrical engineering.
Subjects--Index Terms:

2D materialsIndex Terms--Genre/Form:

542853
Electronic books.

Emerging Two-dimensional Transition Metal Dichalcogenides : = Growth, Light-matter Interactions and Devices.
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