Photoluminescence studies of GaAs/GaAlAs multiple quantum well heterostructures

The photoluminescence excited by He:Ne and Nd:YAG lasers of GaAs/Ga_0.75Al_0.25As multiple quantum well heterostructures grown by MBE was measured as a function of temperature from 4.2 K up to room temperature and for different pumping powers at constant temperature. The excitonic transitions associated with carriers confined in the quantum wells as well as other transitions associated with impurities either already present in the substrates or introduced into the samples during growth are identified in the spectra and fully characterized. From Arrhenius plots of the photoluminescence peak integrated intensities versus inverse temperature, activation energies are estimated for acceptor defects in the samples as well as for quantum well related excitonic transitions. Photoluminescence polarization experiments demonstrate a dramatic manifestation of the selection rules governing heavy hole and light hole optical transitions in quantum wells.