Synopsis: Masking the true effect?

New measurements of silicon nanostructures cast doubt on the possibility that they support a giant piezoresistive effect.
Synopsis figure
Credit: J. Milne et al., Phys. Rev. Lett. (2010)

Piezoresistance—the effect of mechanical changes on resistance—is currently used to improve the performance of silicon-based electronic devices. Several recent publications have reported an effect called giant piezoresistance in silicon nanowires: an applied mechanical stress appears to change the wire’s resistance by an amount that is orders of magnitude greater than what is found in bulk silicon. For understandable reasons, this is intriguing to scientists and engineers working in areas ranging from nanoelectromechanical systems (NEMS) to biosensors.

Now, in their article in Physical Review Letters, Jason Milne and Alistair Rowe at Ecole Polytechnique and Steve Arscott at the Institute d’Electronique, de Microélectronique et de Nanotechnologie, both in France, and Christoph Renner at the University of Geneva, Switzerland, present evidence suggesting that the reported giant piezoresistance may have been an artifact.

Working with various silicon nano- and microstructures, the authors show that electrons and holes trapped at the surface, and not mechanical stress, are responsible for the large swings in resistance. In effect, the very act of measuring the resistance changes its value. The new work indicates that the magnitude of piezoresistance in wires is really no different from that in bulk silicon. Moreover, the charge trapping (or, “dielectric relaxation”) that occurs at the surface both swamps the true piezoresistance and results in apparent giant piezoresistance signatures that are identical to what was reported earlier. While Milne et al.’s results may not quite mean a back-to-the-drawing-board scenario, it points to the importance of making sure—in future experiments—that applied stress alone is causing the changes in resistance in these structures. – Sami Mitra


Features

More Features »

Announcements

More Announcements »

Subject Areas

Semiconductor PhysicsNanophysics

Previous Synopsis

Nanophysics

Qubits, meet photons

Read More »

Next Synopsis

Particles and Fields

The X factor

Read More »

Related Articles

Synopsis: The Dichalcogenide Gets Two Faces
Semiconductor Physics

Synopsis: The Dichalcogenide Gets Two Faces

Electric fields applied on either side of a thin, semiconducting transition-metal dichalcogenide create a superconducting layer atop a metallic layer within the material. Read More »

Synopsis: Single-Electron Sensitivity in CCD Pixels
Semiconductor Physics

Synopsis: Single-Electron Sensitivity in CCD Pixels

A CCD design relying on multiple charge measurements has achieved a precision that allows the detection of a single electron per pixel. Read More »

Viewpoint: Squeezed Environment Boosts Engine Performance
Nanophysics

Viewpoint: Squeezed Environment Boosts Engine Performance

A tiny engine can surpass the Carnot limit of efficiency when researchers engineer the thermal properties of the environment. Read More »

More Articles