Processing and properties of (Mo,Cr) oxycarbides from MOCVD

Wei, Wen‐Cheng J.; Lo, Ming-Hung

doi:10.1002/(sici)1099-0739(199803)12:3<201::aid-aoc692>3.0.co;2-t

Cited by 20 publications

(8 citation statements)

References 24 publications

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“…[1142] as model precursors. The choice was based on the fact that both are readily available, well-established high purity (>99.9%) MOCVD sources with know thermochemical properties [1141,[1143][1144][1145][1146][1147].…”

Section: Vii25 Gas Precursorsmentioning

confidence: 99%

Production and processing of graphene and related materials

et al. 2020

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We present an overview of the main techniques for production and processing of graphene and related materials (GRMs), as well as the key characterization procedures. We adopt a ‘hands-on’ approach, providing practical details and procedures as derived from literature as well as from the authors’ experience, in order to enable the reader to reproduce the results. Section is devoted to ‘bottom up’ approaches, whereby individual constituents are pieced together into more complex structures. We consider graphene nanoribbons (GNRs) produced either by solution processing or by on-surface synthesis in ultra high vacuum (UHV), as well carbon nanomembranes (CNM). Production of a variety of GNRs with tailored band gaps and edge shapes is now possible. CNMs can be tuned in terms of porosity, crystallinity and electronic behaviour. Section covers ‘top down’ techniques. These rely on breaking down of a layered precursor, in the graphene case usually natural crystals like graphite or artificially synthesized materials, such as highly oriented pyrolythic graphite, monolayers or few layers (FL) flakes. The main focus of this section is on various exfoliation techniques in a liquid media, either intercalation or liquid phase exfoliation (LPE). The choice of precursor, exfoliation method, medium as well as the control of parameters such as time or temperature are crucial. A definite choice of parameters and conditions yields a particular material with specific properties that makes it more suitable for a targeted application. We cover protocols for the graphitic precursors to graphene oxide (GO). This is an important material for a range of applications in biomedicine, energy storage, nanocomposites, etc. Hummers’ and modified Hummers’ methods are used to make GO that subsequently can be reduced to obtain reduced graphene oxide (RGO) with a variety of strategies. GO flakes are also employed to prepare three-dimensional (3d) low density structures, such as sponges, foams, hydro- or aerogels. The assembly of flakes into 3d structures can provide improved mechanical properties. Aerogels with a highly open structure, with interconnected hierarchical pores, can enhance the accessibility to the whole surface area, as relevant for a number of applications, such as energy storage. The main recipes to yield graphite intercalation compounds (GICs) are also discussed. GICs are suitable precursors for covalent functionalization of graphene, but can also be used for the synthesis of uncharged graphene in solution. Degradation of the molecules intercalated in GICs can be triggered by high temperature treatment or microwave irradiation, creating a gas pressure surge in graphite and exfoliation. Electrochemical exfoliation by applying a voltage in an electrolyte to a graphite electrode can be tuned by varying precursors, electrolytes and potential. Graphite electrodes can be either negatively or positively intercalated to obtain GICs that are subsequently exfoliated. We also discuss the materials that can be amenable to exfoliation, by ...

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Section: Vii25 Gas Precursorsmentioning

confidence: 99%

Production and processing of graphene and related materials

et al. 2020

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“…are widely used in numerous applications, such as electronics, optoelectronics, photocatalysis, and energy technologies, superior materials may be found in mixed anion inorganic materials, such as metal oxynitrides, 1,2 oxychalcogenides, [3][4][5] oxycarbides, 6 carbonitrides, 7 borocarbides, 8 and boronitrides. 9 Due to their varied crystal structures, anion ordering, 10 and ability to tune properties with anion composition, mixed anion inorganic materials span a broad range of physical, chemical, and electronic properties, providing opportunities to improve material performance for a variety of applications.…”

Section: Introductionmentioning

confidence: 99%

Combining reactive sputtering and rapid thermal processing for synthesis and discovery of metal oxynitrides

et al. 2015

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Recent efforts have demonstrated enhanced tailoring of material functionality with mixed anion materials, yet exploratory research with mixed anion chemistries is limited by the sensitivity of these materials to synthesis conditions. Synthesis of a particular metal oxynitride compound by traditional reactive annealing requires specific, limited ranges of both oxygen and nitrogen chemical potentials to establish equilibrium between the solid-state material and a reactive atmosphere. Using Ta-O-N as an example system, we describe a combination of reactive sputter deposition and rapid thermal processing (RTP) for synthesis of mixed anion inorganic materials. Heuristic optimization of reactive gas pressures to attain a desired anion stoichiometry is discussed, and the ability of RTP to enable amorphous to crystalline transitions without preferential anion loss is demonstrated through the controlled synthesis of nitride, oxide, and oxynitride phases.

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“…In Figure 2b, for the sample prepared via three-stage MOCVD (black), the peak at approximately 43.2 • is ascribed to MOCVD-processed Mo. The use of Mo(CO) 6 (a carbonyl group precursor) appears to result in carbon contamination and, thereby, a different crystal structure [22][23][24]. However, it is difficult to distinguish between the αand β-CIS phases based only on XRD characterization, because these phases are crystallography coherent.…”

Section: Resultsmentioning

confidence: 99%

Characterization of MOCVD-Prepared CIS Solar Cells

Lee

Lee²,

Lee

et al. 2021

Energies

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Chalcopyrite Cu(In,Ga)Se2 (CIGS) solar cells prepared via metal-organic chemical vapor deposition (MOCVD) are one of the candidates for highly advanced photovoltaic devices. This is because of their effectiveness and potential for reducing production costs through large-scale production. However, research on MOCVD-prepared solar cells is progressing slower than that on other types of solar cells, primarily because the preparation of CuInSe2 (CIS)-based films via MOCVD is relatively more sophisticated. In this study, we analyzed CIS solar cells prepared via three-stage MOCVD and processed with relatively simple precursors and techniques. We achieved an energy-conversion efficiency of 7.39% without applying a buffer layer. Instead, we applied a Cu-deficient layer to create a buried pn junction. Ultimately, we demonstrated that the fabrication of fully-MOCVD-processed CIS photovoltaic devices is feasible.

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Processing and properties of (Mo,Cr) oxycarbides from MOCVD

Cited by 20 publications

References 24 publications

Production and processing of graphene and related materials

Production and processing of graphene and related materials

Combining reactive sputtering and rapid thermal processing for synthesis and discovery of metal oxynitrides

Characterization of MOCVD-Prepared CIS Solar Cells

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