INTERWELL AND INTRAWELL MAGNETOEXCITONS IN GAAS ALGAAS SUPERLATTICES/

The formation of spatially indirect (interwell) excitons in superlatti ces (SLs) with different barrier widths (different tunneling coupling) is experimentally investigated in a strong enough magnetic field with the use of photoluminescence (PL), photoluminescence excitation (PLE) , reflectance spec tra and time-resolved technique. The experimental c onditions for the observation of interwell excitons in SLs without ext ernally breaking inversion symmetry are identified and the distinct ex citonic state is found to be located between Is-exciton and the onset of the miniband absorption. Magnetic field; perpendicular to the layer s, strongly modifies the interwell and intrawell excitonic states and transforms the system to the weak coupling regime. The effect of inter well exciton conversion into intrawell one due to exciton-exciton coll isions has been observed at a high excitation regime and confirmed by time-resolved spectroscopy experiments under pulsed picosecond excitat ion.