Lecture

Van der Waals Materials: 2D Crystals

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In course

MSE-484: Properties of semiconductors and related nanostructures

This course explains the origin of optical and electrical properties of semiconductors. The course elaborates how they change when the semiconductors are reduced to sizes of few nanometers. The course provides also the basis to use software to calculate th ...

Description

This lecture discusses the unique properties of van der Waals materials, focusing on 2D crystals with strong in-plane bonds and weak interlayer coupling. It covers the exfoliation process, dimensionality effects, crystal structures, band properties, lattice vibrations, and stacking configurations. The instructor explores the impact of layer sequencing, lattice vibrations, band structures, spin-orbit interactions, and the transition from spintronics to valleytronics. Additionally, the lecture delves into the functional properties of transition metal dichalcogenides, the effects of parallel/anti-parallel stacking, and the significance of Moiré patterns and strain modulation in 2D materials.

Instructors (2)

Valerio Piazza

Teaching & PhD PhD Students Claire Valentine Blaga, Matilde Cantele, Julia Sarah Marhic Past EPFL PhD Students as codirector Michele Zendrini Courses Functional properties of materials MSE-210 The main objective of this course is to present the concepts allowing the understanding of the fundamental principles that enable to predict the properties of the materials. The goal is that with these concepts, one will be able to realize material design and/or to understand novel materials.

Anna Fontcuberta i Morral

2014 Associate Professor at the Institut des Matériaux, EPFL 2008 Assistant Professor Tenure Track at the Institut des Matériaux, EPFL 2009 Habilitation in Physics, Technische Universität München 2005-2010 Marie Curie Excellence Grant Team Leader at Walter Schottky Institut, Technische Universität München, on leave from Centre National de la Recherche Scientifique (CNRS, France) 2004-2005 Visiting Scientist at the California Institute of Technology, on leave from CNRS; Senior Scientist and co-founder of Aonex Technologies (a startup company for large area layer transfer of InP and Ge on foreign substrates for the main application of multi-junction solar cells) 2003 Permanent Research Fellow at CNRS, Ecole Polytechnique, France 2001-2002 Postdoctoral Scholar at the California Institute of Technology Study of wafer bonding and hydrogen-induced exfoliation processes for integration of mismatched materials in views of photovoltaic applications Sponsor: Professor Harry A. Atwater 1998-2001 PhD in Materials Science, Ecole Polytechnique Study of polymorphous silicon: growth mechanisms, optical and structural properties. Application to Solar Cells and Thin Film Transistors Advisor: Pere Roca i Cabarrocas 1997-1998 Diplôme dEtudes Approfondis (D.E.A.) in Materials Science at Université Paris XI, France . 1993-1997 BA in Physics at Universitat de Barcelona

Official source

Related concepts (32)

Spintronics

Spintronics (a portmanteau meaning spin transport electronics), also known as spin electronics, is the study of the intrinsic spin of the electron and its associated magnetic moment, in addition to its fundamental electronic charge, in solid-state devices. The field of spintronics concerns spin-charge coupling in metallic systems; the analogous effects in insulators fall into the field of multiferroics.

Spin–orbit interaction

In quantum physics, the spin–orbit interaction (also called spin–orbit effect or spin–orbit coupling) is a relativistic interaction of a particle's spin with its motion inside a potential. A key example of this phenomenon is the spin–orbit interaction leading to shifts in an electron's atomic energy levels, due to electromagnetic interaction between the electron's magnetic dipole, its orbital motion, and the electrostatic field of the positively charged nucleus.

Valence and conduction bands

In solid-state physics, the valence band and conduction band are the bands closest to the Fermi level, and thus determine the electrical conductivity of the solid. In nonmetals, the valence band is the highest range of electron energies in which electrons are normally present at absolute zero temperature, while the conduction band is the lowest range of vacant electronic states. On a graph of the electronic band structure of a semiconducting material, the valence band is located below the Fermi level, while the conduction band is located above it.

Electronic band structure

In solid-state physics, the electronic band structure (or simply band structure) of a solid describes the range of energy levels that electrons may have within it, as well as the ranges of energy that they may not have (called band gaps or forbidden bands). Band theory derives these bands and band gaps by examining the allowed quantum mechanical wave functions for an electron in a large, periodic lattice of atoms or molecules.

Angular momentum coupling

In quantum mechanics, the procedure of constructing eigenstates of total angular momentum out of eigenstates of separate angular momenta is called angular momentum coupling. For instance, the orbit and spin of a single particle can interact through spin–orbit interaction, in which case the complete physical picture must include spin–orbit coupling. Or two charged particles, each with a well-defined angular momentum, may interact by Coulomb forces, in which case coupling of the two one-particle angular momenta to a total angular momentum is a useful step in the solution of the two-particle Schrödinger equation.

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