Journal of Vacuum Science & Technology A, Vol.16, No.2, 805-809, 1998
Transition behavior from coupled to uncoupled GaAs/InAs double quantum wells
The electronic structures of the InAs single and double quantum wells buried in bulk GaAs (001) are presented based on the sp(3)s* empirical tight-binding model. Both electrons and holes are found to be confined in the c-axis direction around the inserted InAs monomolecular plane with a localization length of the order of 110 Angstrom. The inserted InAs monolayer is, therefore, playing the role of a quantum well for all charge carriers and, as a consequence, the formed heterojunction is of type I. The system, composed of two InAs monolayers buried in GaAs and separated by N monolayers of GaAs, is studied versus the barrier thickness (N). Our results of the variation of band gap energy as a function of barrier thickness (N) are in excellent agreement with the available photoluminescence data when a small valence band offset (of order 80 meV including the spin-orbit effects) is employed. A critical barrier thickness of about 220 Angstrom is suggested to decouple the InAs quantum wells.