Search query: vapor deposition procress

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abstract: Stabilizing monolayer nitrides with silicon Transition metal carbides and nitrides are nonlayered materials that in monolayer form have potentially useful electronic and chemical properties. These monolayers are usually made by chemical etching that produces flakes with surface defects that have poor air and water stability. Hong et al. report that introducing silicon during chemical vapor deposition growth of molybdenum nitride passivates the surface and prevents island formation. Centimeter scale monolayer films of the semiconductor MoSi2N4 form as a MoN2 layer sandwiched by two Si N bilayers. These layers possess high mechanical strength and ambient stability. Science, this issue p. 670 Addition of silicon during film growth stabilized a molybdenum nitride monolayer by sandwiching it between two Si N bilayers. Identifying two dimensional layered materials in the monolayer limit has led to discoveries of numerous new phenomena and unusual properties. We introduced elemental silicon during chemical vapor deposition growth of nonlayered molybdenum nitride to passivate its surface, which enabled the growth of centimeter scale monolayer films of MoSi2N4. This monolayer was built up by septuple atomic layers of N Si N Mo N Si N, which can be viewed as a MoN2 layer sandwiched between two Si N bilayers. This material exhibited semiconducting behavior (bandgap ~1.94 electron volts) high strength ~66 gigapascals) and excellent ambient stability. Density functional theory calculations predict a large family of such monolayer structured two dimensional layered materials, including semiconductors, metals, and magnetic half metals.
author_names: Yi-Lun Hong

Zhibo Liu

Lingqian Wang

Tianya Zhou

Wei Ma

Chuan Xu

Shun Feng

Long Chen

Maolin Chen

Dongming Sun

Xing-Qiu Chen

Hui-Ming Cheng

Wencai Ren
title: Chemical vapor deposition of layered two dimensional MoSi2N4 materials
venue: Science
year: 2020

abstract: Two dimensional (2D) materials have attracted increasing research interest because of the abundant choice of materials with diverse and tunable electronic, optical, and chemical properties. Moreover, 2D material based heterostructures combining several individual 2D materials provide unique platforms to create an almost infinite number of materials and show exotic physical phenomena as well as new properties and applications. To achieve these high expectations, methods for the scalable preparation of 2D materials and 2D heterostructures of high quality and low cost must be developed. Chemical vapor deposition (CVD) is a powerful method which may meet the above requirements, and has been extensively used to grow 2D materials and their heterostructures in recent years, despite several challenges remaining. In this review of the challenges in the CVD growth of 2D materials, we highlight recent advances in the controlled growth of single crystal 2D materials, with an emphasis on semiconducting transition metal dichalcogenides. We provide insight into the growth mechanisms of single crystal 2D domains and the key technologies used to realize wafer scale growth of continuous and homogeneous 2D films which are important for practical applications. Meanwhile, strategies to design and grow various kinds of 2D material based heterostructures are thoroughly discussed. The applications of CVD grown 2D materials and their heterostructures in electronics, optoelectronics, sensors, flexible devices, and electrocatalysis are also discussed. Finally, we suggest solutions to these challenges and ideas concerning future developments in this emerging field.
author_names: Zhengyang Cai

Bilu Liu

Xiaolong Zou

Hui-Ming Cheng
title: Chemical Vapor Deposition Growth and Applications of Two Dimensional Materials and Their Heterostructures.
venue: Chemical reviews
year: 2018

abstract: Carbon nanomaterials have been extensively used in many applications owing to their unique thermal, electrical and mechanical properties. One of the prime challenges is the production of these nanomaterials on a large scale. This review paper summarizes the synthesis of various carbon nanomaterials via the chemical vapor deposition (CVD) method. These carbon nanomaterials include fullerenes, carbon nanotubes (CNTs) carbon nanofibers (CNFs) graphene, carbide derived carbon (CDC) carbon nano onion (CNO) and MXenes. Furthermore, current challenges in the synthesis and application of these nanomaterials are highlighted with suggested areas for future research.
author_names: Yehia M Manawi

Ayman Samara

Tareq Al-Ansari

Muataz Ali Atieh
title: A Review of Carbon Nanomaterials' Synthesis via the Chemical Vapor Deposition (CVD) Method
venue: Materials
year: 2018

abstract: Graphene, in its ideal form, is a two dimensional (2D) material consisting of a single layer of carbon atoms arranged in a hexagonal lattice. The richness in morphological, physical, mechanical, and optical properties of ideal graphene has stimulated enormous scientific and industrial interest, since its first exfoliation in 2004. In turn, the production of graphene in a reliable, controllable, and scalable manner has become significantly important to bring us closer to practical applications of graphene. To this end, chemical vapor deposition (CVD) offers tantalizing opportunities for the synthesis of large area, uniform, and high quality graphene films. However, quite different from the ideal 2D structure of graphene, in reality, the currently available CVD grown graphene films are still suffering from intrinsic defective grain boundaries, surface contaminations, and wrinkles, together with low growth rate and the requirement of inevitable transfer. Clearly, a gap still exits between the reality of CVD derived graphene, especially in industrial production, and ideal graphene with outstanding properties. This Review will emphasize the recent advances and strategies in CVD production of graphene for settling these issues to bridge the giant gap. We begin with brief background information about the synthesis of nanoscale carbon allotropes, followed by the discussion of fundamental growth mechanism and kinetics of CVD growth of graphene. We then discuss the strategies for perfecting the quality of CVD derived graphene with regard to domain size, cleanness, flatness, growth rate, scalability, and direct growth of graphene on functional substrate. Finally, a perspective on future development in the research relevant to scalable growth of high quality graphene is presented.
author_names: Li Lin

Bing Deng

Jingyu Sun

Hailin Peng

Zhongfan Liu
title: Bridging the Gap between Reality and Ideal in Chemical Vapor Deposition Growth of Graphene.
venue: Chemical reviews
year: 2018

abstract: In this work we present a low cost and scalable technique, via ambient pressure chemical vapor deposition (CVD) on polycrystalline Ni films, to fabricate large area approximately cm2) films of single to few layer graphene and to transfer the films to nonspecific substrates. These films consist of regions of 1 to approximately 12 graphene layers. Single or bilayer regions can be up to 20 mum in lateral size. The films are continuous over the entire area and can be patterned lithographically or by prepatterning the underlying Ni film. The transparency, conductivity, and ambipolar transfer characteristics of the films suggest their potential as another materials candidate for electronics and opto electronic applications.
author_names: Alfonso Reina

Xiaoting Jia

John T Ho

Daniel Nezich

Hyungbin Son

Vladimir Bulovic

Mildred S Dresselhaus

Jing Kong
title: Large area, few layer graphene films on arbitrary substrates by chemical vapor deposition.
venue: Nano letters
year: 2009

abstract: 3D assembly of graphene sheets (GSs) is important for preserving the merits of the single atomic layered structure. Simultaneously, vertical growth of GSs has long been a challenge for thermal chemical vapor deposition (CVD) Here, vertical growth of the GSs is achieved in a thermal CVD reactor and a novel 3D graphene structure, 3D graphene fibers (3DGFs) is developed. The 3DGFs are prepared by carbonizing electrospun polyacrylonitrile fibers in NH3 and subsequently in situ growing the radially oriented GSs using thermal CVD. The GSs on the 3DGFs are densely arranged and interconnected with the edges fully exposed on the surface, resulting in high performances in multiple aspects such as electrical conductivity (3.4 x 104 1.2 x 105 S m 1 electromagnetic shielding (60 932 dB cm2 g 1 and superhydrophobicity and superoleophilicity, which are far superior to the existing 3D graphene materials. With the extraordinary properties along with the easy scalability of the simple thermal CVD, the novel 3DGFs are highly promising for many applications such as high strength and conducting composites, flexible conductors, electromagnetic shielding, energy storage, catalysis, and separation and purification. Furthermore, this strategy can be widely used to grow the vertical GSs on many other substrates by thermal CVD.
author_names: Jie Zeng

Xixi Ji

Yihui Ma

Zhongxing Zhang

Shuguang Wang

Zhonghua Ren

Chunyi Zhi

Jie Yu
title: 3D Graphene Fibers Grown by Thermal Chemical Vapor Deposition.
venue: Advanced materials
year: 2018

abstract: Summary Two dimensional (2D) heterostructures, which are constructed via vertical stacking or lateral stitching of various 2D materials, have attracted considerable attention during the past 5 years. However, it is still a big challenge to achieve controllable construction of both lateral and vertical 2D heterostructures, which is considered to be an essential step toward further theoretical research and practical applications. Recently, chemical vapor deposition (CVD) has shown high controllability in the synthesis of various 2D materials, which has inspired intensive investigations into CVD growth of 2D heterostructures. Here, research progress in the controllable CVD growth of numerous 2D heterostructures is discussed. The review mainly covers three state of the art strategies (temperature triggering, precursor design, and substrate engineering) for improving the controllability over 2D heterostructures. We conclude with the current challenges and future directions in this rapidly developing field.
author_names: Tao Zhang

Lei Fu
title: Controllable Chemical Vapor Deposition Growth of Two Dimensional Heterostructures
year: 2018

abstract: Brookite is the least investigated phase of TiO2 due to the synthetic difficulty of obtaining the pure phase. Here, we present the first ever chemical vapor deposition synthesis of pure brookite TiO2 thin films. The films were highly crystalline and phase pure as determined by X ray diffraction and Raman spectroscopy studies. Scanning electron microscopy studies showed the films to have a structured morphology consisting of pyramidal features. The photocatalytic properties of the brookite film, tested using stearic acid under UVA (365 nm) irradiation, were superior to both an anatase film grown under similar conditions and NSG Activ glass. Transient absorption spectroscopy showed that the innate electron hole recombination dynamics are similar in brookite and anatase, akin to previous reports. The superior activity of the brookite film is hence attributed to the higher surface area compared to anatase.
author_names: Abdullah M Alotaibi

Sanjayan Sathasivam

Benjamin A D Williamson

Andreas Kafizas

Carlos Sotelo-Vazquez

Alaric Taylor

David O Scanlon

Ivan P Parkin
title: Chemical Vapor Deposition of Photocatalytically Active Pure Brookite TiO2 Thin Films
year: 2018

abstract: Large area MoS(2) atomic layers are synthesized on SiO(2) substrates by chemical vapor deposition using MoO(3) and S powders as the reactants. Optical, microscopic and electrical measurements suggest that the synthetic process leads to the growth of MoS(2) monolayer. The TEM images verify that the synthesized MoS(2) sheets are highly crystalline.
author_names: Yi-Hsien Lee

Xin-Quan Zhang

Wenjing Zhang

M T Chang

Cheng-Te Lin

Kai Chang

Ya-Chu Yu

Jacob Tse-Wei Wang

Chia-Seng Chang

Lain-Jong Li

Tsung-Wu Lin
title: Synthesis of large area MoS2 atomic layers with chemical vapor deposition.
venue: Advanced materials
year: 2012

abstract: b In2S3 is a natural defective III VI semiconductor attracting considerable interests but lack of efficient method for its 2D form fabrication. Here, for the first time, this paper reports controlled synthesis of ultrathin 2D b In2S3 flakes via a facile space confined chemical vapor deposition method. The natural defects in b In2S3 crystals, clearly revealed by optical spectra and optoelectronic measurement, strongly modulate the (opto) electronic of as fabricated b In2S3 and render it a broad detection range from visible to near infrared. Particularly, the as fabricated b In2S3 photodetector shows a high photoresponsivity of 137 A W 1, a high external quantum efficiency of 3.78 x 104% and a detectivity of 4.74 x 1010 Jones, accompanied with a fast rise and decay time of 6 and 8 ms, respectively. In addition, an interesting linear response to the testing power intensities range is observed, which can also be understood by the presence of natural defects. The unique defective structure and intrinsic optical properties of b In2S3, together with its controllable growth, endow it with great potential for future applications in electronics and optoelectronics.
author_names: Wenjuan Huang

Lin Gan

Hao-Hsun Yang

Nan Zhou

Renyan Wang

Wanhui Wu

Huiqiao Li

Ying Ma

Haibo Zeng

Tianyou Zhai
title: Controlled Synthesis of Ultrathin 2D b In2S3 with Broadband Photoresponse by Chemical Vapor Deposition
year: 2017