MECHANISMS OF STRAINED ISLAND FORMATION IN MOLECULAR-BEAM EPITAXY OF INAS ON GAAS(100)

Results of a systematic examination of InAs island formation on GaAs(1 00) as a function of deposition conditions and thickness are presented . A non-Arrhenius dependence of the island density on substrate temper ature and a decrease in the island density with increasing As4 Pressur e at lower substrate temperatures is observed, indicating that current ly popular frameworks of compound semiconductor molecular-beam epitaxi cal growth and island formation mechanism(s) need to be enlarged. Plan -view transmission electron microscopy (TEM) and use of the behavior o f Moire fringes provides the island size distribution and demarcation between coherent and incoherent islands. Photoluminescence (PL) behavi or is shown to vary significantly with the growth conditions and to co rrelate to the attendant structural nature revealed by TEM. The issue of lateral quantum confinement (i.e., three-dimensional islands as qua ntum boxes) is shown to be subtle and complex, calling for caution in interpreting PL behavior. The results suggest that a regular array of ''quantum boxes'' made of coherently strained volumes of uniform size may be achieved via growth on prepatterned mesas.