Abstract
Photoluminescence (PL) and PL excitation (PLE) measurements have been performed in biased double quantum well heterostructures. The recombination of electrons, e, with holes, h, located in the same or in two adjacent wells, has been investigated for different exciting power densities, P, and temperatures, T. For increasing P or decreasing T, a sharp transition from two gases of photoexcited electrons and holes, spatially separated and confined in the two wells, to two two-dimensional (2D) liquids has been observed. The gas-to-2D-liquid transition is evidenced by a strong screening of applied biases and by major changes in the optical spectra. The phase diagram in the plane of the system has been determined. Time-resolved PL, cw PL, and PLE in the presence of a magnetic field normal to the quantum wells support the presence of e- and h-liquid phases in the two wells with a critical density equal to and a binding energy of 2.5 meV.
- Received 22 September 1999
DOI:https://doi.org/10.1103/PhysRevB.61.8420
©2000 American Physical Society