Cooperative Recombination of a Quantized High-Density Electron-Hole Plasma

TL;DR

This study explores how high-density electron-hole plasmas in quantum wells exhibit cooperative recombination, leading to a transition from omnidirectional to collimated photoluminescence under strong magnetic fields and intense excitation.

Contribution

It demonstrates the first observation of cooperative recombination effects in a quantized high-density electron-hole plasma within semiconductor quantum wells.

Findings

Transition from omnidirectional to collimated PL emission at critical conditions

Correlation between spectral features and the onset of directed emission

Evidence of cooperative recombination in a quantized, high-density plasma

Abstract

We investigate photoluminescence from a high-density electron-hole plasma in semiconductor quantum wells created via intense femtosecond excitation in a strong perpendicular magnetic field, a fully-quantized and tunable system. 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. In addition, changes in the linewidth, carrier density, and magnetic field scaling of the PL spectral features correlate precisely with the onset of random directionality, indicative of cooperative recombination from a high density population of free carriers in a semiconductor environment.