Polarizability of a donor impurity in dielectrically modulated core–shell nanodots

• Electric field effect on the donor states in ZnS/CdSe inverted core–shell dots is studied.
• Electron cloud localization strongly depends on the shell thickness.
• Binding energy is increased by the dielectric mismatch at the dot interfaces.
• Polarizability of the donor varies with the dot size and field direction.

Simultaneous effects of the quantum confinement and electric field on the donor states in ZnS/CdSe core–shell nanodots surrounded by a wide-gap dielectric material are investigated. The results show a pronounced blue-shift of the binding energy due to the dielectric confinement. While in smaller dots the electron is located in the core even for off-center impurities, for increased outer radius it becomes squeezed almost entirely into the shell material. Therefore, the impurity states could be tuned by properly tailoring the heterostructure parameters (size, impurity position) and the dielectric environment, as well as by varying the electric field strength.