Carrier dynamics in quantum ring in a quantum well: Magnetic field and non-parabolicity effects

Abstract

Binding energy of a hydrogenic donor impurity in GaAs/Al0.3Ga0.7As Quantum Ring (QR) under the influence of an external magnetic field along with the effect of conduction band non-parabolicity has been calculated. QR has been confined in a quantum well of suitable width which serves as the height of the quantum ring. The external magnetic field enhances the binding energy of the donor because of its additional confinement. Since QR is a one dimensional structure, this additional confinement given by the magnetic field restricts the motion of the carrier further and increases the localization which in turn increases the binding energy of the donor. The incorporation of band non-parabolicity significantly alters the effective mass of the carrier which reduces the binding energy. Application of magnetic field in larger rings reduces the binding energy because of the larger lateral space provided by the ring. Strengthening the inner barrier greatly increases the binding energy irrespective of magnetic field. The effect of impurity location on the binding energy has also been calculated. Also it has been observed that band Non-parabolicity is more effective for edge impurities when compared to other impurity locations.