Lecture

Metal-Semiconductor Junction: Physics Overview

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In course

PHYS-433: Semiconductor physics and light-matter interaction

Lectures on the fundamental aspects of semiconductor physics and the main properties of the p-n junction that is at the heart of devices like LEDs & laser diodes. The last part deals with light-matter interaction phenomena in bulk semiconductors such as ab ...

Description

This lecture covers the physics of metal-semiconductor junctions, focusing on work function, electron affinity, Schottky barrier height, surface states, Ohmic contacts, heterojunctions, band alignment, and SiO2 layers formation. It also discusses light absorption, absorption processes, and semiconductor physics.

Instructor

Raphaël Butté

Raphaël Butté was born in Paris, France, in 1973. He received the PhD degree from the University Claude Bernard, Lyon, France, in 2000 for his research on the structural and optoelectronic properties of hydrogenated nanostructured silicon thin films with potential applications for photovoltaics and thin film transistors. He then moved to the University of Sheffield (2000-2003), UK, to work as postdoctoral research associate in the group of Prof. Maurice S. Skolnick (Fellow of the Royal Society). His research shifted to the optical properties of III-V semiconductors with a main focus on the nonlinear optical properties of cavity polaritons occurring in GaAs-based microcavities driven under resonant optical excitation. In 2004, he moved to Ecole Polytechnique Fédérale de Lausanne (EPFL) as scientific collaborator in charge of optical spectroscopy at LASPE (http://laspe.epfl.ch/), a newly established laboratory directed by Prof. Nicolas Grandjean. In 2010, he became permanent member of staff (Scientific Collaborator and Lecturer). He was promoted to the position of Senior Scientist in 2016. His current research activity deals with planar waveguides, microdisks and photonic crystals made from III-nitride semiconductors. In particular, he is leading the activity focusing on: (i) the physics of exciton-polaritons in planar waveguides and (ii) high-β photonic crystal nanolasers. He is the author of 119 scientific articles published in peer-reviewed international journals, 14 publications published in peer reviewed journals following an international conference (Web of Science > 4500 citations, h-index: 36; Google Scholar > 6200 citations, h-index: 42) and 6 book chapters. He has given 30 invited talks in International Conferences/Winter-Summer Schools/Workshops. He has been the Publications Chair/Guest Editor of the Proceedings of the 5th International Workshop on Nitride semiconductors (IWN2008) and also served as Scientific Secretary of IWN2008 and of the 5th International Conference on Spontaneous Coherence in Excitonic Systems (ICSCE5). In 2012, he was one of the 149 scientists recognized by the Outstanding Referee program (http://publish.aps.org/OutstandingReferees) of the American Physical Society (APS) selected from a pool of roughly 60,000 currently active referees. Since September 2019, he is an Editorial Board Member of the newly launched open access APS journal, Physical Review Research. From September 2013 until December 2017, he was one of the Editors of the journal "Superlattices and Microstructures" (Elsevier). Since September 2015 he is a member of the Physics Doctoral School Teaching Committee. He was also a member of the EPFL Teaching Conference from September 2015 until August 2017.

Official source

Ontological neighbourhood

Physics

Condensed matter physics: Solid-state physics

Related concepts (32)

Metal–semiconductor junction

In solid-state physics, a metal–semiconductor (M–S) junction is a type of electrical junction in which a metal comes in close contact with a semiconductor material. It is the oldest practical semiconductor device. M–S junctions can either be rectifying or non-rectifying. The rectifying metal–semiconductor junction forms a Schottky barrier, making a device known as a Schottky diode, while the non-rectifying junction is called an ohmic contact.

Ohmic contact

An ohmic contact is a non-rectifying electrical junction: a junction between two conductors that has a linear current–voltage (I–V) curve as with Ohm's law. Low-resistance ohmic contacts are used to allow charge to flow easily in both directions between the two conductors, without blocking due to rectification or excess power dissipation due to voltage thresholds. By contrast, a junction or contact that does not demonstrate a linear I–V curve is called non-ohmic.

Semiconductor device

A semiconductor device is an electronic component that relies on the electronic properties of a semiconductor material (primarily silicon, germanium, and gallium arsenide, as well as organic semiconductors) for its function. Its conductivity lies between conductors and insulators. Semiconductor devices have replaced vacuum tubes in most applications. They conduct electric current in the solid state, rather than as free electrons across a vacuum (typically liberated by thermionic emission) or as free electrons and ions through an ionized gas.

Semiconductor

A semiconductor is a material which has an electrical conductivity value falling between that of a conductor, such as copper, and an insulator, such as glass. Its resistivity falls as its temperature rises; metals behave in the opposite way. Its conducting properties may be altered in useful ways by introducing impurities ("doping") into the crystal structure. When two differently doped regions exist in the same crystal, a semiconductor junction is created.

Heterojunction

A heterojunction is an interface between two layers or regions of dissimilar semiconductors. These semiconducting materials have unequal band gaps as opposed to a homojunction. It is often advantageous to engineer the electronic energy bands in many solid-state device applications, including semiconductor lasers, solar cells and transistors. The combination of multiple heterojunctions together in a device is called a heterostructure, although the two terms are commonly used interchangeably.

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