Geometrical Effects on Exchange Coupling in System of Near-Surface Donors and Quantum Dots

The value of exchange energy for near-surface double-donor and double-quantum dot structures under the effect of external electric field has been calculated using unrestricted Hartree–Fock method. The dependences of exchange energy on geometric parameters have been obtained. It has been found that the location of donor centers near the surface of the semiconductor leads to an increase in the exchange energy. Approximate formulas for the dependence of the exchange energy on the distance between the centers of quantum dots are suggested. It has been shown that exchange coupling control is less sensitive to electric field as compared to magnetic field, and electron density relocation at large electric fields should be taken into account when designing devices based on the structures under study.