Optical transitions of Al0.35Ga0.65As/GaAs asymmetric double quantum wellsgrown on GaAs(n11)A (n <= 4) substrates

The optical transitions in Al0.35Ga0.65As/GaAs asymmetric double quantum we lls (ADQWs) grown on GaAs(n11)A (n less than or equal to 4) substrates were studied by photoluminescence at low temperatures. The redshift of two PL p eaks for substrate orientation far from the (100) plane is attributed to th e large anisotropy of the heavy-hole band in the different GaAs orientation s. The energy difference of the two transitions also shows a similar shift. By comparing the PL measurements with a simple effective mass calculation, the effective mass of the heavy hole on GaAs(n11)A (n = 1, 2, 3, 4) planes is found to be about 0.95, 0.73, 0.54 and 0.41m(0), respectively. The effe ct of As pressures on PL peak energies in ADQWs is also studied. The As pre ssure-dependence of PL peak energies is attibuted to a decrease of the Ga d esorption rate with increasing As pressures on GaAs(n11)A substrates. (C) 1 999 Elsevier Science Ltd. All rights reserved.