A critical review of the effects of fluid dynamics on graphene growth in atmospheric pressure chemical vapor deposition

Chemical vapor deposition (CVD) of graphene has attracted high interest in the electronics industry due to its potential scalability for large-scale production. However, producing a homogeneous thin-film graphene with minimal defects remains a challenge. Studies of processing parameters, such as gas precursors, flow rates, pressures, temperatures, and substrate types, focus on improving the chemical aspect of the deposition. Despite the many reports on such parameters, studies on fluid dynamic aspects also need to be considered since they are crucial factors in scaling up the system for homogenous deposition. Once the deposition kinetics is thoroughly understood, the next vital step is fluid dynamics optimization to design a large-scale system that could deliver the gas uniformly and ensure maximum deposition rate with the desired property. In this review, the influence of fluid dynamics in graphene CVD process was highlighted. The basics and importance of CVD fluid dynamics was introduced. It is understood that the fluid dynamics of gases can be controlled in two ways: via reactor modification and gas composition. This paper begins first with discussions on horizontal tubular reactor modifications. This is followed by mechanical properties of the reactant gasses especially in terms of dimensionless Reynolds number which provides information on gas flow regime for graphene CVD process at atmospheric pressure. Data from the previous literature provide the Reynolds number for various gas compositions and its relation to graphene quality. It has been revealed that hydrogen has a major influence on the fluid dynamic conditions within the CVD, hence affecting the quality of the graphene produced. Focusing on atmospheric pressure CVD, suggestions for up-scaling into larger CVD reactors while maintaining similar fluid properties were also provided

Optimizing diamond-like carbon coatings - From experimental era to artificial intelligence

Diamond-like carbon (DLC) coatings are widely used for numerous engineering applications due to their superior multi-functional properties. Deposition of good quality DLC is governed by energy per unit carbon atom or ion and plasma kinetics, which are independent parameters. Translating independent parameters to dependent parameters to produce a best DLC is subjected to deposition method, technology, and system configurations which may involve above 50 combinations of bias voltage, chamber pressure, deposition temperature, gas flow rate, etc. Hence DLC coatings are optimized to identify the best parameters which yield superior properties. This article covers DLC introduction, the role of independent parameters, translation of independent parameters to dependent parameters, and discussion of four generations of DLC optimization. The first-generation of DLC optimization experimentally optimizes the parameter-to-property relationship, and the second-generation describes multi-parameter optimization with a hybrid of experimental and statistical-based analytical methods. The third generation covers the optimization of DLC deposition parameters with a hybrid of statistical methods and artificial intelligence (AI) tools. The ongoing fourth generation not only performs multi-parameter and multi-property optimization but also use AI tools to predict DLC properties and performance with higher accuracy. It is expected that AI-driven DLC optimizations and progress in virtual synthesis of DLC will not only assist in resolving DLC challenges specific to emerging markets and complex environments, but will also become a pathway for DLC to enter a digital-twin era

Feature Papers in Electronic Materials Section

This book entitled "Feature Papers in Electronic Materials Section" is a collection of selected papers recently published on the journal Materials, focusing on the latest advances in electronic materials and devices in different fields (e.g., power- and high-frequency electronics, optoelectronic devices, detectors, etc.). In the first part of the book, many articles are dedicated to wide band gap semiconductors (e.g., SiC, GaN, Ga2O3, diamond), focusing on the current relevant materials and devices technology issues. The second part of the book is a miscellaneous of other electronics materials for various applications, including two-dimensional materials for optoelectronic and high-frequency devices. Finally, some recent advances in materials and flexible sensors for bioelectronics and medical applications are presented at the end of the book

Enhancing additively manufactured polymers through functional diamond-like carbon coatings

By providing the required structural modification to polymeric materials through functional coatings, polymer-based materials (PBMs) can provide significant material functionality and improve performance in both material design and product finishing. This added advantage may provide extended durability, aesthetic appeal, barrier functions and improve tribological performance to the polymer. PBMs especially additively manufactured polymers (3D printed polymers) come with enormous physical, structural, mechanical and chemical challenges in both design and product application phases and can only be mitigated using an integrated surface engineering approach. In this study, the use of a novel microwave-plasma-enhanced chemical vapour deposition (MW-PECVD) technique has been assessed for its viability in depositing single layer diamond-like carbon (DLC) coatings directly unto 3D printed polymers. Before the deposition, a comprehensive assessment to understand the performance limitations of the mechanical, thermal, pore structure and water absorption properties of all selected 3D printed parts were made. The Hauzer Flexicoat 850 system which houses within two microwave sources was utilized in the DLC deposition process to offer a uniquely designed and tailored coating structure. Three DLC coatings were developed and deposited onto two photocurable additively manufactured polymers namely acrylonitrile butadiene styrene-like (3D ABS) and Verogray. The parameters of particular interest for the deposition process including N_2,〖 C〗_2 H_2 gas flow rates and micro-wave power input were studied to determine the effect these process variations have on the coating architecture, structure and performance from the nano to the macro scale. Initial adhesion testing of the coating using scratch testing showed complete coating failure at loads < 5N. A preliminary design of experiment (DOE) approach was established as a base framework to understand the relationship between the process parameters and coating adhesion. Further coatings based on this design were produced to explore the variable applications and limitations for characterising the hard-on-soft polymer-coating matrix. Coating characterisation techniques such as scratch testing, nano-indentation, Raman spectroscopy, X-ray photoelectron spectroscopy (XPS) were employed to assess both the mechanical and structural properties of the coating. The coating produced in this work has shown measurable mechanical and structural properties, in particular high hardness and improved adhesion in comparison with similar DLCs reported in the literature. The ability of the coating to provide additional functionality such as tribological and water vapour barrier functions is assessed in this work. This study has shown that it is viable to use DLC for both barrier and tribological applications

Solid State Circuits Technologies

The evolution of solid-state circuit technology has a long history within a relatively short period of time. This technology has lead to the modern information society that connects us and tools, a large market, and many types of products and applications. The solid-state circuit technology continuously evolves via breakthroughs and improvements every year. This book is devoted to review and present novel approaches for some of the main issues involved in this exciting and vigorous technology. The book is composed of 22 chapters, written by authors coming from 30 different institutions located in 12 different countries throughout the Americas, Asia and Europe. Thus, reflecting the wide international contribution to the book. The broad range of subjects presented in the book offers a general overview of the main issues in modern solid-state circuit technology. Furthermore, the book offers an in depth analysis on specific subjects for specialists. We believe the book is of great scientific and educational value for many readers. I am profoundly indebted to the support provided by all of those involved in the work. First and foremost I would like to acknowledge and thank the authors who worked hard and generously agreed to share their results and knowledge. Second I would like to express my gratitude to the Intech team that invited me to edit the book and give me their full support and a fruitful experience while working together to combine this book

Tribological Behavior of Functional Surface: Models and Methods

Material loss due to wear and corrosion and high resistance to motion generate high costs. Therefore, minimizing friction and wear is a problem of great importance. This book is focused on the tribological behavior of functional surfaces. It contains information regarding the improvement of tribological properties of sliding elements via changes in surface topography. Tribological impacts of surface texturing depending on the creation of dimples on co-acting surfaces are also discussed. The effects of various coatings on the minimization of friction and wear and corrosion resistance are also studied. Friction can be also reduced by introducing a new oil

Cutting Edge Nanotechnology

The main purpose of this book is to describe important issues in various types of devices ranging from conventional transistors (opening chapters of the book) to molecular electronic devices whose fabrication and operation is discussed in the last few chapters of the book. As such, this book can serve as a guide for identifications of important areas of research in micro, nano and molecular electronics. We deeply acknowledge valuable contributions that each of the authors made in writing these excellent chapters

EUROSENSORS XVII : book of abstracts

Fundação Calouste Gulbenkien (FCG).Fundação para a Ciência e a Tecnologia (FCT)