Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:


Semiconductor interfaces: Big opportunities for tiny insulators

A model that predicts real-world behaviors of insulator interfaces makes designing ‘nano-electronic’ materials significantly simpler

Advances in miniaturization have made electronic devices cheaper and more powerful, but these procedures also create new challenges for materials scientists. For example, traditional silicon dioxide insulators used in field-effect transistors begin to leak small amounts of current at nanoscale dimensions.

A new theoretical model enables accurate predictions of dipoles at oxide interfaces (left, electron microscopy image) using the classical property of electronegativity (right). The scale shows how two elements with different relative electronegativities align at an interface.

Copyright : © 2013 A*STAR Institute of Materials Research and Engineering

To combat this problem, researchers have developed insulators called ‘high-k dielectrics’ that link heavier elements, such as hafnium or zirconium, into insulating oxide films with exceptional charge-isolating capabilities.

Integrating high-k dielectrics into circuits, however, creates a different manufacturing problem. Localized electric fields known as charged dipoles can form at insulator–semiconductor interfaces and generate unwanted voltages that impact device performance. Sing Yang Chiam from the A*STAR Institute of Materials Research and Engineering in Singapore and co-workers have now developed a model that can identify interface dipole problems before they appear1 — a finding that promises to help end the ‘trial-and-error’ design issues typical of high-k dielectrics.

Currently, materials scientists employ extensive quantum mechanical calculations to determine whether or not new high-k dielectrics will have interface dipoles. Chiam and co-workers investigated a more intuitive approach: they linked the appearance of interface dipoles to the classical property of electronegativity, a number that relates an element’s electron-attracting power to its position in the periodic table.

Scientists have previously avoided estimating dipoles with electronegativity values because, in many cases, they predict incorrect electric field polarities. To resolve this discrepancy, Chiam and co-workers correlated theoretical electronegativity with experimental ‘charge neutrality levels’ — electronic energies required to counterbalance dipoles on insulator interfaces. After measuring the charge neutrality on several different high-k dielectrics with X-ray and ultraviolet radiation (see image), the team plotted this data against electronegativity. They discovered that a simple linear equation connected the two parameters.

Further manipulation of this equation revealed it could also predict a so-called ‘dipole neutrality point’ (DNP) where interfacial dipoles flip polarity. Armed with this new theoretical tool, the researchers investigated both well-known and novel high-k dielectric/semiconductor interfaces. They found that the DNP concept provided accurate predictions of dipole polarity and strength: the offset voltages needed to turn on a high-k dielectric field-effect transistor closely matched values generated from the electronegativity values.

Chiam notes that the straightforwardness of this model should make it exceptionally practical for scientific discovery. “This is the simplest method to find dipoles at material interfaces before starting experiments,” he says. “Our model can predict what kinds of bulk or interface modifications are needed to offset dipole values — a significant time saving over traditional approaches.”

The A*STAR-affiliated researchers contributing to this research are from the Institute of Materials Research and Engineering

Associated links
Journal information
Liu, Z. Q., Chim, W. K., Chiam, S. Y., Pan, J. S. & Ng, C. M. An interface dipole predictive model for high-k dielectric/semiconductor heterostructures using the concept of the dipole neutrality point. Journal of Materials Chemistry 22, 17887–17892 (2012).

A*STAR Research | Research asia research news
Further information:

More articles from Power and Electrical Engineering:

nachricht Greater Range and Longer Lifetime
26.10.2016 | Technologie Lizenz-Büro (TLB) der Baden-Württembergischen Hochschulen GmbH

nachricht 3-D-printed magnets
26.10.2016 | Vienna University of Technology

All articles from Power and Electrical Engineering >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Etching Microstructures with Lasers

Ultrafast lasers have introduced new possibilities in engraving ultrafine structures, and scientists are now also investigating how to use them to etch microstructures into thin glass. There are possible applications in analytics (lab on a chip) and especially in electronics and the consumer sector, where great interest has been shown.

This new method was born of a surprising phenomenon: irradiating glass in a particular way with an ultrafast laser has the effect of making the glass up to a...

Im Focus: Light-driven atomic rotations excite magnetic waves

Terahertz excitation of selected crystal vibrations leads to an effective magnetic field that drives coherent spin motion

Controlling functional properties by light is one of the grand goals in modern condensed matter physics and materials science. A new study now demonstrates how...

Im Focus: New 3-D wiring technique brings scalable quantum computers closer to reality

Researchers from the Institute for Quantum Computing (IQC) at the University of Waterloo led the development of a new extensible wiring technique capable of controlling superconducting quantum bits, representing a significant step towards to the realization of a scalable quantum computer.

"The quantum socket is a wiring method that uses three-dimensional wires based on spring-loaded pins to address individual qubits," said Jeremy Béjanin, a PhD...

Im Focus: Scientists develop a semiconductor nanocomposite material that moves in response to light

In a paper in Scientific Reports, a research team at Worcester Polytechnic Institute describes a novel light-activated phenomenon that could become the basis for applications as diverse as microscopic robotic grippers and more efficient solar cells.

A research team at Worcester Polytechnic Institute (WPI) has developed a revolutionary, light-activated semiconductor nanocomposite material that can be used...

Im Focus: Diamonds aren't forever: Sandia, Harvard team create first quantum computer bridge

By forcefully embedding two silicon atoms in a diamond matrix, Sandia researchers have demonstrated for the first time on a single chip all the components needed to create a quantum bridge to link quantum computers together.

"People have already built small quantum computers," says Sandia researcher Ryan Camacho. "Maybe the first useful one won't be a single giant quantum computer...

All Focus news of the innovation-report >>>



Event News

#IC2S2: When Social Science meets Computer Science - GESIS will host the IC2S2 conference 2017

14.10.2016 | Event News

Agricultural Trade Developments and Potentials in Central Asia and the South Caucasus

14.10.2016 | Event News

World Health Summit – Day Three: A Call to Action

12.10.2016 | Event News

Latest News

VDI presents International Bionic Award of the Schauenburg Foundation

26.10.2016 | Awards Funding

3-D-printed magnets

26.10.2016 | Power and Electrical Engineering

Advanced analysis of brain structure shape may track progression to Alzheimer's disease

26.10.2016 | Health and Medicine

More VideoLinks >>>