GROWTH OF PSEUDOMORPHIC INXGA1-XAS/GAPYAS1-Y MULTIPLE-QUANTUM-WELL STRUCTURES ON GAAS BY GAS-SOURCE MOLECULAR-BEAM EPITAXY

We report gas source molecular beam epitaxial growth of strain balanced InxGa1-xAs/GaPyAs1-y multiple quantum well structures on GaAs that exhibit sharp excitonic absorption features at 1.06 Am. Because these materials also lie at the extreme limit of elastic stability, we examine the mechanism by which strain initially relaxes using RHEED and X-ray diffraction. A structural instability is found for a critical strain layer thickness beyond which a transition from smooth to rough growth occurs. When strain relaxation occurs our measurements indicate that surface energy driven processes cause the layer to form lateral domains. The domains consist of regions containing small misorientation angular tilts. Domain formation has a direct consequence on the field dependent absorption measurements in strain balanced multiple quantum well structures on GaAs.