INXGA1-XSB/GAAS QUANTUM-WELL STRUCTURES GROWN BY MOLECULAR-BEAM EPITAXY

Molecular beam epitaxy was used to grow lattice mismatched InxGa1-xSb layers on GaAs substrates. Optical and structural properties were examined by photoluminescence (PL) and transmission electron microscopy (TEM). Growth of the strained layers was found to be in layer-by-layer mode up to a critical layer thickness (CLT) where three dimensional growth and eventually dislocation generation occured. TEM revealed dislocations and stacking faults in a 2 monolayer thich InO.25Ga0.75Sb layer while a 3 monolayer thick InSb layer was defect free. The PL experiments were in general accordance with the TEM data showing an increase of critical layer thickness with increasing In-mole fraction. A reduced PL-intensity for the GaSb quantum wells is discussed in terms of indirect bandgap transitions and a staggered band line up between GaAs and GaSb. © 1992.