Hydrogenic-Donor Impurity Binding Energy Dependence of the Electric Field in GaAs/AlxGa1-xAs Quantum Rings

Using a variational method with two-parameter trial wave function and the effective mass approximation, the binding energy of a donor impurity in GaAs/AlxGa1-xAs cylindrical quantum ring (QR) subjected to an external field is calculated. It is shown that the donor impurity binding energy is highly dependent on the QR structure parameters (radial thickness and height), impurity position, and external electric field. The binding energy increases inchmeal as the QR parameters (radial thickness and height) decrease until a maximum value for a central impurity and then begins to drop quickly. The applied electric field can significantly modify the spread of electronic wave function in the QR and shift electronic wave function from the donor position and then leads to binding energy changes. In addition, results for the binding energies of a hydrogenic donor impurity as functions of the impurity position and applied electric field are also presented.