Difference of anisotropic structures of InAs/GaAs quantum dots between organometallic vapor-phase epitaxy and molecular beam epitaxy

The anisotropies of the baseline in and [1 1 0] of InAs quantum dots (QDs) fabricated by molecular beam epitaxy (MBE) and organometallic vapor-phase epitaxy (OMVPE) are investigated. The structural and optical difference between QDs by MBE and OMVPE are investigated through an atomic force microscopy, a transmission electron microscopy, and a photoluminescence polarization measurement. It is found that the InAs QD structural anisotropy in MBE agrees with the individual growth rate anisotropy. Moreover, it is found that the mixture of the different structural anisotropies is unique in OMVPE at low growth temperature (440°C) and the growth mode is complex. From the photoluminescence polarization measurement, the InAs QD structures which mainly contribute to the optical property are decided by the plus and minus of the polarization degree of the ground state, and it is shown that the baseline anisotropy of the QDs mainly agrees with the growth rate anisotropy.