Excited-state spectroscopy of single lateral self-assembled InGaAs quantum dot molecules

Abstract

We perform excited-state spectroscopy of single self-assembled lateral InGaAs quantum dot molecules embedded in a planar microcavity structure, which are grown using a combination of metal-organic vapor phase and solid-source molecular beam epitaxy. The individual quantum dot molecules (QDMs) consist of two single dots that are coupled along the $[1\overline{1}0]$ crystal direction via electron tunneling. By microphotoluminescence excitation spectroscopy, we investigate the presence and structure of the excited states confined in the system using a wide-band tunable Ti:sapphire laser source. We show that the excited states are very similar even for different molecules. We attribute this to the presence of a potential basin below the quantum dots that levels the differences among various QDMs.