ROLE OF BUFFER SURFACE-MORPHOLOGY AND ALLOYING EFFECTS ON THE PROPERTIES OF INAS NANOSTRUCTURES GROWN ON INP(001)

We show the role played by the buffer surface morphology and by alloyi ng effects on the size, shape and lateral distribution of InAs nanostr uctures grown on InP(001) substrates by molecular beam epitaxy. Three buffers, viz., In0.53Ga0.47As, In0.52Al0.48As, and InP lattice matched on InP have been studied. Differences in nanostructure morphology and in carrier confinement have been evaluated by atomic force microscopy and by low-temperature photoluminescence measurements, respectively. Alongside the classical relaxation mode through two-dimensional/three- dimensional surface morphology change, a chemical relaxation mode has to be introduced as a competitive mode of relaxation of strained layer s. This chemical relaxation mode, due to alloying between the InAs dep osit and the buffer, is thought to be responsible for most of the obse rved differences in the InAs nanostructure properties. (C) 1998 Americ an Institute of Physics. [S0003-6951(98)03146-5].