A relatively simple method for implementing the conditions of the built-in Coulomb blockade in a quantum dot directly during the epitaxial growth of a heterostructure is proposed. This is achieved by adjusting the Fermi energy to the energy of the electron level in the quantum dot by forming a p-n-p doping profile by introducing a thin GaAs layer with n-type conductivity into the structure at a certain distance from the quantum dot layer. In this case, a neutral or charged state of an exciton in a QD can be realized without applying an external electric field, but only by varying the doping level in the n-GaAs layer and its distance to the quantum dot in accordance with the developed analytical model. Experimental studies of the spin dynamics and statistics of single-photon emission made it possible to obtain comprehensive information on the charge state of single quantum dots, the emission of which is coupled with the fundamental mode of a microcolumn microresonator. A significant increase in the probability of obtaining the required charge state for quantum dots formed using the Stranski–Krastanov growth mechanism is shown. For neutral and multiply charged quantum dots, this probability is in the range of 90-96%, and for singly charged quantum dots in the range of 70-95%. This approach represents a significant step towards complete control of optical processes in individual quantum dots for their potential application in quantum photonics.

A.I.Galimov, Yu.M.Serov, M.V.Rakhlin et al.,
JETP Letters 121, issue 5 (2025)