OPTICALLY DETECTED MAGNETIC-RESONANCE OF EXCITONS AND CARRIERS IN PSEUDODIRECT GAAS/ALAS SUPERLATTICES

Optically detected magnetic resonance (ODMR) of electrons, holes and heavy-hole excitons has been studied in type-II GaAs/AlAs superlattices and in pseudodirect superlattices close to the type-II/type-I transition in the range of periods from 22 to 75 angstrom. The exchange energy splitting of the excitons and g-factor of the holes have been measured as a function of the period of the superlattice and the well (GaAs) thickness, respectively. For the first time, a variation of the exchange interaction within the emission line of the heavy-hole excitons has been observed. The ODMR and level anticrossing signals of excitons and carriers have been obtained in the pseudodirect superlattices with luminescence decay time down to 10 ns. Two types of excitons have been observed in some superlattices. The luminescence line was shown to consist of two components with different wavelength for the heavy-hole exciton emission and for the recombination of electrons and holes when the exchange interaction is vanishingly small.