Competition Effects of Electric and Magnetic Fields on Impurity Binding Energy in a Disc-Shaped Quantum Dot in the Presence of Pressure and Temperature

We have theoretically studied the combination effects of the electric and magnetic fields on the binding energy of an on-center donor impurity in disc-shaped GaAs/Al_0.3Ga_0.7As quantum dots (QDs) with emphasis on the competition effects between the two fields under externally applied pressure and temperature. The electric field is applied along the radial direction of the QD, while the magnetic field is applied along the growth direction. The numerical method we employed in the present calculations is the potential morphing method in the framework of the effective mass approximation. Our results show that the two fields exhibit a competition effect on the donor binding energy, leading to an invariant binding energy as in the zero field case at a critical line. This line separates the region corresponding to the “red shift” of the donor binding energy from the one referring to the “blue shift” of the binding energy. Comparing to the magnetic field effect, increasing in the QD sizes or applied pressure is found to favour more its electric counterpart, enlarging the region satisfied by the “red shift” of the donor binding energy. The temperature effect appears to decrease the donor binding energy. However, the competition effects between the two fields retain the same when the temperature varies.