Giant burst of the emission line intensity of spatially indirect excitons in GaAs/AlGaAs double quantum wells

A study is reported on the low-temperature (T less than or equal to 30 K) p hotoluminescence in the spatially indirect exciton line in GaAs/Al0.33Ga0.6 7As double quantum wells as a function of optical pump power and applied el ectric held. We have revealed a giant (threefold) burst of luminescence int ensity in a part of the spectral profile of the indirect-exciton line occur ring at certain values of the external electric field, temperature, and opt ical pumping. We have also observed that this part of the indirect-exciton line profile varies in intensity (fluctuates) with time with a characterist ic period of tens of seconds. The results obtained are discussed within a m odel of the Bose-Einstein condensation of a system of two-dimensional boson s that have, besides the free, a discrete energy spectrum lying below the b ottom of the free-state band. (C) 2000 MAIK "Nauka/Interperiodica".