Lecture

Contact Resistance in Semiconductor Devices

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In course

EE-567: Semiconductor devices II

Students will learn about understanding the fundamentals and applications of emerging nanoscale devices, materials and concepts. Remark: at least 5 students should be enrolled for the course to be given ...

Description

This lecture covers the concept of contact resistance in semiconductor devices, discussing its practical implications, measurement techniques such as the 4-probe and TLM methods, and the impact of contact geometry on resistance scaling. It also explores quantum resistance in ballistic conductors, quantized conductance in materials like GaAs, graphene, and MoS₂, and the challenges of spin injection due to conductivity mismatch. Additionally, it examines the band alignment in heterostructures, valley polarization by spin injection, and strategies for reducing contact resistance through phase engineering, doping, and contact transfer.

Instructors (2)

Mihai Adrian Ionescu

Adrian M. Ionescu is Full Professor at the Swiss Federal Institute of Technology, Lausanne, Switzerland. He received the B.S./M.S. and Ph.D. degrees from the Polytechnic Institute of Bucharest, Romania and the National Polytechnic Institute of Grenoble, France, in 1989 and 1997, respectively. He has held staff and/or visiting positions at LETI-CEA, Grenoble, France and INP Grenoble, France and Stanford University, USA, in 1998 and 1999. Dr. Ionescu has published more than 600 articles in international journals and conferences. He received many Best Paper Awards in international conferences, the Annual Award of the Technical Section of the Romanian Academy of Sciences in 1994 and the Blondel Medal in 2009 for contributions to the progress in engineering sciences in the domain of electronics. He is the 2013 recipient of the IBM Faculty Award in Engineering. He served the IEDM and VLSI conference technical committees and was the Technical Program Committee (Co)Chair of ESSDERC in 2006 and 2013. He is a member of the SATW. He is director of the Laboratory of Micro/Nanoelectronic Devices (NANOLAB).

Andras Kis

2015− Associate professor, EPFL, STI, Institute of Electrical Engineering (IEL) and Materials Science and Engineering Institute (IMX) 2008−2015 Tenure-track assistant professor at EPFL, School of Engineering (STI), Institute of Electrical Engineering (IEL) 2004−2007 Postdoctoral researcher at the University of California, Berkeley, Physics Department in the group of Prof. Zettl 2000−2003 PhD student at EPFL, Faculty of basic sciences, Institute of physics of complex matter, group of Prof. Forró 1994−1999 MS, Physics, University of Zagreb, Croatia 1994 Baccalaureate, MIOC (Mathematical and Informational Educational Center) high school

Official source

Related concepts (31)

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.

Graphene

Graphene (ˈgræfiːn) is an allotrope of carbon consisting of a single layer of atoms arranged in a hexagonal lattice nanostructure. The name is derived from "graphite" and the suffix -ene, reflecting the fact that the graphite allotrope of carbon contains numerous double bonds. Each atom in a graphene sheet is connected to its three nearest neighbors by σ-bonds and a delocalised π-bond, which contributes to a valence band that extends over the whole sheet.

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.

Quantum wire

In mesoscopic physics, a quantum wire is an electrically conducting wire in which quantum effects influence the transport properties. Usually such effects appear in the dimension of nanometers, so they are also referred to as nanowires. If the diameter of a wire is sufficiently small, electrons will experience quantum confinement in the transverse direction. As a result, their transverse energy will be limited to a series of discrete values.

Quantum Hall effect

The quantum Hall effect (or integer quantum Hall effect) is a quantized version of the Hall effect which is observed in two-dimensional electron systems subjected to low temperatures and strong magnetic fields, in which the Hall resistance Rxy exhibits steps that take on the quantized values where VHall is the Hall voltage, Ichannel is the channel current, e is the elementary charge and h is Planck's constant. The divisor ν can take on either integer (ν = 1, 2, 3,...) or fractional (ν = 1/3, 2/5, 3/7, 2/3, 3/5, 1/5, 2/9, 3/13, 5/2, 12/5,.

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