  A series of (Ga,In)As/GaAs/Ga(As,Sb) multi-quantum well heterostructures is
analyzed using temperature- and power-dependent photoluminescence (PL)
spectroscopy. Pronounced PL variations with sample temperature are observed and
analyzed using microscopic many-body theory and band structure calculations
based on the k$\cdot$p method. This theory-experiment comparison reveals an
unusual, temperature dependent variation of the band alignment between the
(Ga,In)As and Ga(As,Sb) quantum wells.
