Nanomechanics In Van Der Waals Heterostructures

Micro/nano-mechanical systems are a crucial part of the modern world providing a plethora of sensing and actuation functionalities used in everything from the largest cargo ships to the smallest hand-held electronics; from the most advanced scientific and medical equipment to the simplest household items. Over the past few decades, the processes used to produce these devices have improved, supporting dramatic reductions in size, but there are fundamental limits to this trend that require a new production paradigm. The 2004 discovery of graphene ushered in a new era of condensed matter physics research, that of two-dimensional materials. Being only a few atomic layers thick, this new class of materials exhibit unprecedented mechanical strength and flexibility and can couple to electric, magnetic and optical signals. Additionally, they can be combined to form van der Waals heterostructures in an almost limitless number of ways. They are thus ideal candidates to reduce the size and extend the capabilities of traditional micro/nano-mechanical systems and are poised to redefine the technological sphere. This thesis attempts to develop the framework and protocols required to produce and characterise micro/nano-mechanical devices made from two-dimensional materials. Graphene and its insulating analogue, hexagonal boron nitride, are the most widely studied materials and their heterostructures are used as the test-bed for potential device architectures and capabilities. Interlayer friction, electro-mechanical actuation and surface reconstruction are some of the key phenomena investigated in this work.

2D Semiconductor Materials and Devices reviews the basic science and state-of-art technology of 2D semiconductor materials and devices. Chapters discuss the basic structure and properties of 2D semiconductor materials, including both elemental (silicene, phosphorene) and compound semiconductors (transition metal dichalcogenide), the current growth and characterization methods of these 2D materials, state-of-the-art devices, and current and potential applications. Reviews a broad range of emerging 2D electronic materials beyond graphene, including silicene, phosphorene and compound semiconductors Provides an in-depth review of material properties, growth and characterization aspects—topics that could enable applications Features contributions from the leading experts in the field

Van der Waals Heterostructures A comprehensive resource systematically detailing the developments and applications of van der Waals heterostructures and devices Van der Waals Heterostructures is essential reading to understand the developments made in van der Waals heterostructures and devices in all aspects, from basic synthesis to physical analysis and heterostructures assembling to devices applications, including demonstrated applications of van der Waals heterostructure on electronics, optoelectronics, and energy conversion, such as solar energy, hydrogen energy, batteries, catalysts, biotechnology, and more. This book starts from an in-depth introduction of van der Waals interactions in layered materials and the forming of mixed-dimensional heterostructures via van der Waals force. It then comprehensively summarizes the synthetic methods, devices building processes and physical mechanism of 2D van der Waals heterostructures, and devices including 2D-2D electronics, 2D-2D optoelectronics, and mixed dimensional van der Waals heterostructures. In Van der Waals Heterostructures, readers can expect to find specific information on: The current library of 2D semiconductors and the current synthesis and performances of 2D semiconductors Controllable synthesis and assemble van der Waals heterostructures, physics of the van der Waals interface, and multi-field coupling effects 2D-2D electronics, 2D-2D optoelectronics, mixed dimensional van der Waals heterostructures, and van der Waals heterostructure applications on energy conversion Insight into future perspectives of the van der Waals heterostructures and devices with the detailed effective role of 2D materials for integrated electrical and electronic equipment

The advent of graphene and, more recently, two-dimensional materials has opened new perspectives in electronics, optoelectronics, energy harvesting, and sensing applications. This book, based on a Special Issue published in Nanomaterials - MDPI covers experimental, simulation, and theoretical research on 2D materials and their van der Waals heterojunctions. The emphasis is the physical properties and the applications of 2D materials in state-of-the-art sensors and electronic or optoelectronic devices.

Contains the latest research advances in computational nanomechanics in one comprehensive volume Covers computational tools used to simulate and analyse nanostructures Includes contributions from leading researchers Covers of new methodologies/tools applied to computational nanomechanics whilst also giving readers the new findings on carbon-based aggregates (graphene, carbon-nanotubes, nanocomposites) Evaluates the impact of nanoscale phenomena in materials

This thesis shares new findings on the interfacial mechanics of graphene-based materials interacting with rigid/soft substrate and with one another. It presents an experimental platform including various loading modes that allow nanoscale deformation of atomically thin films, and a combination of atomic force microscopy (AFM) and Raman spectroscopy that allows both displacement and strain to be precisely measured at microscale. The thesis argues that the rich interfacial behaviors of graphene are dominated by weak van der Waals force, which can be effectively modulated using chemical strategies. The continuum theories are demonstrated to be applicable to nano-mechanics and can be used to predict key parameters such as shear/friction and adhesion. Addressing key interfacial mechanics issues, the findings in thesis not only offer quantitative insights in the novel features of friction and adhesion to be found only at nanoscale, but will also facilitate the deterministic design of high-performance graphene-based nanodevices and nanocomposites.

2D Materials for Electronics, Sensors and Devices: Synthesis, Characterization, Fabrication and Application provides an overview of various top-down and bottom-up synthesis techniques, along with stitching, stacking and stoichiometric control methods for different 2D materials and their heterostructures. The book focuses on the widespread applications of various 2D materials in high-performance and low-power sensors, field effect devices, flexible electronics, straintronics, spintronics, brain-inspired electronics, energy harvesting and energy storage devices. This is an important reference for materials scientists and engineers looking to gain a greater understanding on how 2D materials are being used to create a range of low cost, sustainable products and devices. Discusses the major synthesis and preparation methods of a range of emerging 2D electronic materials Provides state-of–the-art information on the most recent advances, including theoretical and experimental studies and new applications Discusses the major challenges of the mass application of 2D materials in industry

Van der Waals (vdW) ferroelectric CuInP2S6 (CIPS) has attracted intense research interest due to its unique ferroelectric properties that make it promising for potential applications in flexible electronic devices. A mechanical mean, or so-called strain gradient engineering, has been proven as an effective method to modulate its ferroelectric properties, but the key parameter elastic constants Cij has not been accurately measured. Here, we utilized nanoindentation and contact resonance atomic force microscopy (CR-AFM) techniques to measure the elastic modulus on the (001) plane of nanoscale phase separated CuInP2S6-In4/3P2S6 (CIPS-IPS). The Young’s modulus of the CIPS was slightly less than that of the IPS. Density Functional Theory was introduced to obtain the accurate full elastic constant Cij of CIPS and IPS, and we deduced their respective Young’s moduli, all of which are in good agreement with our experimental values. We further discovered the asymmetrical domain switching and proposed an ion-mediated domain switching model. The results provide a reliable experimental reference for strain gradient engineering in the phase field simulation in CIPS-IPS.