Growth mechanism of (InAs)m(GaAs)n strained short-period superlattices grown by molecular beam epitaxy

Abstract

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 ∼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–Krastanov mode. It could be attributed to intermixing of superlattice structure due to the surface segregation of In atoms assisted by thermal energy.