Theoretical calculations reveal the advantage of type-II materials for the use in the intermediate band QD based solar cells. InAs QD's in the AlGaAsSb alloy matrix is the best candidate for the experimental implementation of this idea. This alloy, however, has a large miscibility gap, which complicates their growth on InP substrates. Growth of AlGaAsSb (Eg~1.3-1.4eV) alloys on GaSb substrates was proposed and studied instead. Epitaxial layers of AlGaAsSb were grown by metal-organic vapor-phase epitaxy on AIX200 set-up.
For the realization of Stranski-Krastanov growth regime of InAs (QD formation), substrates with different misorientation were used. Vicinal faces formation during AlGaAsSb growth has been studied and results of InAs on AlGaAsSb growth are presented.