Self-assembled (In,Ga)As Quantum Posts on GaAs.

We demonstrate a method for the MBE growth of height controlled (In,Ga)As quantum posts (QPs). Its main axis is along the growth direction. they are dislocation free and have a dimensions $\approx $ 20nm and 40nm. From EDX measurements, The Ga$_{.55}$In$_{.45}$As QPs are embedded laterally in a Ga$_{.9}$In$_{.1}$As layer. We have computed the electron and hole levels using an 8 bands, stain dependent, \underline {k.p} effective mass model. Comparison of calculated single particle electron and hole levels with the observed micro-PL spectra single QPs indicates that electrons are spread over the entire QP whereas holes are localized near the seed QD. * This research is sponsored through an NSF-NIRT grant No. CCF 0507295. HJK acknowledges support by the Alexander von Humboldt Foundation.