Collective properties of spatially indirect excitons in asymmetric GaAs AlGaAs double quantum wells

The paper is devoted to the investigation of low-temperature (T = 1.8 and 4 .2 K) luminescence spectra of double GaAs/ Al0.33Ga0.67As asymmetric quantu m wells (DQW) under the changing electric field V-dc, applied normally to t he plane of layers of DQWs. It was found that the full width of half maximu m (FWHM) of the indirect exciton luminescence line (IX) in some interval of V-dc values narrows sharply (up to 3.5 times). In:the transition range of V-dc values, in which there arises a sharp decrease (or increase) of FWHM, abnormally large fluctuations at the time of IX intensity are observed. The dependence of FWHM on the optical pumping level Ip reveals a sharp FWHM de crease in some interval of Ip values. The results are discussed using the,a ssumption that the observed phenomena are due to the appearance of a conden sed state in collective interacting spatially indirect excitons in the DQW, (C) 1999 Elsevier Science Ltd. All rights reserved.