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It used to be difficult to reliably fabricate clean heterostructures using magnetic and superconducting layers. Today this is no longer the case; such reproducible superconductor/ferromagnet heterostructures enable the quantitative study of the rich and varied phenomena associated with ferromagnet/superconductor proximity effects. These structures are eminent, suitable candidates for many switching devices, ranging from non-volatile low power memory elements to quantum computing applications involving Josephson junctions.This book's main purpose is to explain how the equilibrium and transport properties of these heterostructures can be accurately calculated starting from a standard BCS type Hamiltonian. The main techniques, including both analytical and numerical methods, are discussed in detail. Results obtained from these calculations are shown to be in excellent quantitative agreement with experiment.This is a theory book, but the theory is neither abstruse nor esoteric. Knowledge of only introductory graduate physics has been assumed; a solid undergraduate training and a bit of perseverance would also be enough. This book can easily be read and understood by experimentalists, and just about anybody can grasp the basics by referring to the figures and explanations. Quite apart from the manifold applications of superconductor/ferromagnet nanostructures, studying them provides us with considerable insights into fundamental physics and the general study of hybrid nanomaterials.

This book represents a significant advance in our understanding of the synthesis and properties of two-dimensional (2D) materials. The author's work breaks new ground in the understanding of a number of 2D crystals, including atomically thin transition metal dichalcogenides, graphene, and their heterostructures, that are technologically important to next-generation electronics. In addition to critical new results on the direct growth of 2D heterostructures, it also details growth mechanisms, surface science, and device applications of “epi-grade” 2D semiconductors, which are essential to low-power electronics, as well as for extending Moore's law. Most importantly, it provides an effective alternative to mechanically exfoliate 2D layers for practical applications.

This thesis focuses on the energy band engineering of graphene. It presents pioneering findings on the controlled growth of graphene and graphene-based heterostructures, as well as scanning tunneling microscopy/scanning tunneling spectroscopy (STM/STS) studies on their electronic structures. The thesis primarily investigates two classes of graphene-based systems: (i) twisted bilayer graphene, which was synthesized on Rh substrates and manifests van Hove singularities near Fermi Level, and (ii) in-plane h-BN-G heterostructures, which were controllably synthesized in an ultrahigh vacuum chamber and demonstrate intriguing electronic properties on the interface. In short, the thesis offers revealing insights into the energy band engineering of graphene-based nanomaterials, which will greatly facilitate future graphene applications.

This thesis demonstrates that layered heterostructures of two-dimensional crystals graphene, hexagonal boron nitride, and transition metal dichalcogenides provide new and interesting interlayer transport phenomena. Low-energy electron microscopy is employed to study the surface of atomically thin WSe2 prepared by metal-organic chemical vapor deposition on epitaxial graphene substrates, and a method for unambiguously measuring the number of atomic layers is presented. Using very low-energy electrons to probe the surface of similar heterostructures, a relationship between extracted work function differences from the layers and the nature of the electrical contact between them is revealed. An extension of this analysis is applied to surface studies of MoSe2 prepared by molecular beam epitaxy on epitaxial graphene. A large work function difference is measured between the MoSe2 and graphene, and a model is provided which suggests that this observation results from an exceptional defect density in the MoSe2 film. The thesis expounds a theory for computing tunneling currents between two-dimensional crystals separated by a thin insulating barrier; a few situations resulting in resonant tunneling and negative differential resistance are illustrated by computed examples, as well as observed characteristics, for monolayer and bilayer graphene tunneling junctions and transistors.

Quantum size effects are becoming increasingly important in microelectronics, as the dimensions of the structures shrink laterally towards 100 nm and vertically towards 10 nm. Advanced device concepts will exploit these effects for integrated circuits with novel or improved properties. Keeping in mind the trend towards systems on chip, this book deals with silicon-based quantum devices and focuses on room-temperature operation. The basic physical principles, materials, technological aspects, and fundamental device operation are discussed in an interdisciplinary manner. It is shown that silicon-germanium (SiGe) heterostructure devices will play a key role in realizing silicon-based quantum electronics.