Synopsis: Superconducting LED

Light emitting diodes with superconducting electrodes are better photon emitters.
Synopsis figure
H. Sasakura et al., Phys. Rev. Lett. (2011)

The macroscopic quantum coherence of Cooper pairs in a superconductor has been exploited for a variety of applications, including the realization of qubits in quantum information processing and high-speed single-photon detection. The latter application relies on the fact that absorption of photons with energies below the superconducting gap preserves the Cooper pairs, whereas absorption of photons above the threshold destroys them.

Presenting their results in Physical Review Letters, H. Sasakura at Hokkaido University, Japan, and co-workers have demonstrated a unique application of superconductivity to enhance band-to-band radiative recombination in a semiconductor. The setup consists of epitaxially grown light emitting diode (LED) layers made up of n-type InGaAs on top of a p-type InP substrate. The LED layers are then covered by an ohmic contact layer, followed by niobium (Nb) electrodes. Below a certain critical temperature, a Josephson junction is established, with the LED layer sandwiched in between the superconducting Nb electrodes. Most notably, there is a drastic enhancement of photon generation in the LED layer from the recombination of electron Cooper pairs—injected by means of the proximity effect—with holes injected by the p-type electrode. This development opens up the possibility of a new interdisciplinary field: superconducting optoelectronics. – Sarma Kancharla


Features

More Features »

Announcements

More Announcements »

Subject Areas

SuperconductivitySemiconductor Physics

Previous Synopsis

Statistical Physics

Touching Gases Settle Down

Read More »

Next Synopsis

Magnetism

Thin-Skinned Insulators

Read More »

Related Articles

Synopsis: Bismuthates Are Surprisingly Conventional
Superconductivity

Synopsis: Bismuthates Are Surprisingly Conventional

Photoemission experiments challenge the long-held belief that the high-temperature superconductivity of certain bismuth oxides is of the unconventional type. Read More »

Synopsis: Widening the Spin Energy Gap
Spintronics

Synopsis: Widening the Spin Energy Gap

Using a new all-electric technique, researchers triple the energy gap between the two spin states of holes in a 2D quantum well. Read More »

Viewpoint: Crystals with Defects May Be Good for Spintronics
Semiconductor Physics

Viewpoint: Crystals with Defects May Be Good for Spintronics

Dislocation defects are often a nuisance in semiconductors, but theoretical work shows they might offer an improved route to producing spin currents. Read More »

More Articles