GROWTH-MECHANISM OF (INAS)M(GAAS)N STRAINED SHORT-PERIOD SUPERLATTICES GROWN BY MOLECULAR-BEAM EPITAXY

The growth mechanism of (InAs)m(GaAs)n strained short-period superlattices grown on GaAs(001) and InAs(001) substrates was investigated by reflection high-energy electron diffraction and transmission electron microscopy. In the growth on a GaAs substrate, the two-dimensional layer-by-layer growth mode (Frank-Van der Merwe mode) was successfully realized even over the critical thickness when the lattice mismatch is less than approximately 2.4%. In this case, the critical thickness of the grown layer on GaAs was remarkably increased by applying the superlattice structures. However, the strained short-period superlattices on InAs substrate were grown in the Stranski-Krastanov mode. The growth mode of strained short-period superlattices can be explained by the balance of surface and interface free energies, which could relate to the difference of the bonding energy between In-As and Ga-As. The growth mode of strained short-period superlattices depended strongly on the growth temperature. In the relatively high temperature growth, the growth mode of strained short-period superlattice grown on a GaAs substrate was changed from the Frank-Van der Merwe mode to the Stranski-Kranstanov mode. It could be attributed to intermixing of superlattice structure due to the surface segregation of In atoms assisted by thermal energy.