Synopsis

Better transistors through quantum mechanics

Physics 4, s120
More compact transistors may be possible by harnessing the quantum properties of semiconductor heterostructures.
Credit: A. Sciambi et al., Phys. Rev. B (2011)

As chip designers seek to pack more transistors onto every square millimeter of silicon real estate, they run up against a fundamental problem: small devices become overwhelmed by quantum effects. However, some researchers are seeking to turn the tables by pressing quantum mechanics into service as part of the transistor design. In a paper in Physical Review B, Adam Sciambi of Stanford University, California, and his collaborators report their proof-of-principle experiments on a new kind of quantum transistor.

The team has created a two-layer GaAs/AlGaAs quantum well heterostructure, in which the wave function of one layer extends into the second to modulate the tunneling current between the layers. In this design, a voltage on the first quantum well causes that layer to be depleted of carriers, which changes the subband energy level in the well. As the subband energy approaches the top of the quantum well potential, the wave function extends further and further out toward the second layer. When the wave function overlaps the second layer, the tunneling current can increase as much as two orders of magnitude, a substantial degree of gating leverage.

Although the reported design only works at cryogenic temperatures, a different choice of materials, for example, graphene, may allow operation at more technologically relevant temperatures. – David Voss


Subject Areas

Semiconductor Physics

Related Articles

Exciton Ensembles Manifest Coherence
Condensed Matter Physics

Exciton Ensembles Manifest Coherence

Evidence of coherent light emission from excitons in a 2D-material structure could inspire new quantum-technology applications. Read More »

A Solid Observation of Strong Kerr Nonlinearity
Condensed Matter Physics

A Solid Observation of Strong Kerr Nonlinearity

Researchers have demonstrated that a solid can exhibit an enhanced nonlinear optical phenomenon usually seen only in cold atomic gases. Read More »

Semiconductors in the Spotlight
Materials Science

Semiconductors in the Spotlight

A new model suggests that lattice defects are responsible for the way some semiconductors become harder under illumination. Read More »

More Articles