Binding energy of an off-center shallow donor D- in a spherical quantum dot

TL;DR

This paper calculates the binding energy of a negatively charged impurity in a spherical quantum dot, revealing stability conditions and how off-center positions can lead to instability.

Contribution

It introduces a detailed calculation of impurity binding energies considering off-center positions in spherical quantum dots using the configuration interaction method.

Findings

On-center impurities have positive binding energy with a maximum near R_c.

Off-center impurities can have negative binding energy, indicating instability.

Binding energy depends on impurity position and quantum dot radius.

Abstract

The binding energy of a negatively charged hydrogenic impurity with on- and off-center position in a spherical Gaussian quantum dot was calculated with the configuration interaction method. Our calculations show that $E_b$ is always positive for on-center impurities with a maximum near to the radius for one-electron stability of the potential well $R_c$. For off-center positions the binding energy can assume negative values within a range of the quantum dot radius, thus indicating the instability of the system.