Molecular states observed in a single pair of strongly coupled self-assembled InAs quantum dots

Abstract

Molecular states in a SINGLE PAIR of strongly coupled self-assembled InAs quantum dots are investigated using a sub-micron sized single electron transistor containing just a few pairs of coupled InAs dots embedded in a GaAs matrix. We observe a series of well-formed Coulomb diamonds with charging energy of less than 5 meV, which are much smaller than those reported previously. This is because electrons are occupied in molecular states, which are spread over both dots and occupy a large volume. In the measurement of ground and excited state single electron transport spectra with magnetic field, we find that the electrons are sequentially trapped in symmetric and anti-symmetric states. This result is well-explained by numerical calculation using an exact diagonalization method.

PDF file only. 10 pages, 3 figures. In press on Superlattices and Microstructures. Proceedings of 6-th International Conference on New Phenomena in Mesoscopic Systems and 4-th International Conference on Surfaces and Interfaces of Mesoscopic Devices, 1-5 December 2003, Maui, Hawaii