Electronic lifetime engineering using low-temperature GaAs in a quantum well structure

Using an AlAs barrier, it is possible to confine the defects associated to the low temperature grown GaAs in a well-defined portion of the sample. We verified that a minimum thickness of about 5 nm of AlAs is required. Structures with good quality QW and LT-GaAs QW have been grown where the separation between wells could be reduced to a minimum distance of 5 nm. This has been used to design quantum heterostructures where the extension of the electronic wave functions of the different levels over the LT-GaAs regions can be adjusted independently. This controlled overlap opens an alternative way to engineer the lifetime of various electronic subbands. (C) 1999 Elsevier Science B.V. All rights reserved.