Papers by Keyword: Hydrogenic Impurity

Abstract: The binding energy of a hydrogenic donor impurity in cylindrical GaAs quantum ring (QR) subjected to an external magnetic field is calculated within the effect mass approximation using variational method. The binding energy as a function of the QR size (the inner radius, the outer radius), the impurity position and the applied magnetic field is investigated. The results demonstrate that the ground state binding energy behaves as an decreasing function of the outer radius, and the magnetic field. Likewise, the binding energy is an increasing function of the inner radius. The binding energy firstly increases and then decreases with shifting the impurity ion from the internal surface of the QR to the external surface, indicating that there is a maximum.

Abstract: Based on the the effective mass approximation and variational approach, the donor impurity states confined in self-formed GaAs/Al_xGa_1-xAs quantum rings (QRs) are investigated theoretically. A uniform electric field is applied along the growth direction of the QR. The different effective masses in the different regions of the GaAs/Al_xGa_1-xAs QR are taken into consideration. Numerical results show that the binding energy of a donor impurity increases gradually, reaches a maximum value, and then decreases quickly to the special value as the QR height decreases. Given a fixed QR size, the binding energy increases for the impurity located at the center of the QR when the Al composition increases. In addition, it can also be found that when the applied electric field strength increases, the donor binding energy increases for impurities localized at the negative z axis of the QR; however, the donor binding energy decreases slightly for impurities located at the center and positive z axis of the QR.