Time-Integrated Evidence for Superfluorescence from Dense Electron-Hole Magneto-Plasmas in Semiconductor Quantum Wells

TL;DR

This paper demonstrates superfluorescence in semiconductor quantum wells under high magnetic fields, showing a transition from omnidirectional to collimated emission due to cooperative electron-hole recombination.

Contribution

It provides experimental evidence of superfluorescence in quantum wells, a phenomenon previously difficult to observe in semiconductors, under specific high magnetic field and excitation conditions.

Findings

Superfluorescence observed at magnetic fields > 20 T.

Transition from omnidirectional to collimated emission.

Correlation of spectral changes with cooperative recombination.

Abstract

Cooperative spontaneous recombination (superfluorescence) of electron-hole plasmas in semiconductors has been a challenge to observe due to ultrafast decoherence. We argue that superfluorescence can be achieved in quantum-confined semiconductor systems and present experimental evidence for superfluorescence from high-density photoexcited electron-hole plasmas in quantum wells under high magnetic fields (> 20 T). At a critical magnetic field strength and excitation fluence, we observe a clear transition in the band-edge photoluminescence from omnidirectional output to a randomly directed but highly collimated beam. Changes in the linewidth, carrier density, and magnetic field scaling of the emission spectra correlate precisely with the onset of random directionality and are consistent with cooperative recombination. We further investigate the effects of spot size, temperature, and excitation geometry on the emission properties.