Band edge alignment of pseudomorphic GaAs1-ySby on GaAs -: art. no. 195339

Measurements of the transition energies of GaAsSb quantum well samples with different barrier configurations reveal that the conduction band offset of the coherently strained GaAs1-ySby/GaAs heterojunction grown on GaAs has a zero crossing at a Sb mole fraction of y=0.43+/-0.07. A type-I band alignment is formed for lower Sb mole fractions and a type-II band alignment is formed for higher Sb mole fractions. This occurs as a consequence of a considerable amount (58%) of the -1.58 eV bandgap bowing being distributed to the conduction band. As a suitable active material for 1.3 mum emission, pseudomorphic GaAs0.643Sb0.357 grown on GaAs is determined to have a weak, 23+/-23 meV, type-I conduction band offset and a bandgap energy of 928+/-4 meV.