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 quantum wells (DQW) under the changing electric field V-dc, applied normally to the plane of layers of DQWs. It was found that the full width of half maximum (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 decrease in some interval of Ip values. The results are discussed using the,assumption that the observed phenomena are due to the appearance of a condensed state in collective interacting spatially indirect excitons in the DQW, (C) 1999 Elsevier Science Ltd. All rights reserved.