Coulomb oscillations of the current through spin-nondegenerate $p$ states of InAs quantum dots

The electron transport is studied in split-gate structures fabricated on the basis of a modulation-doped heterostructure that contains a single quantum well and self-assembled InAs quantum dots near the 2D electron gas regions. The current passing through the channel with a denumerable set of InAs quantum dots is found to exhibit Coulomb oscillations as a function of the gate voltage. The oscillations are associated with the excited $p$ states of InAs quantum dots, which are characterized by opposite spins and caused by lifting of the spin degeneracy of the $p$ state due to the Coulomb interaction. The Coulomb oscillations of the current are observed up to a temperature of $\sim$20 K. The Coulomb energy is found to be $\Delta E_c=12.5$ meV, which agrees well with the theoretical estimates for the $p$ states of quantum dots in the structures under study.