Excited states and infrared transition energies of a donor impurity in cylindrical GaAs–Ga 0.6Al 0.4As quantum well wires under the action of an applied magnetic field

Abstract

We report a calculation of the binding and transition energies for a donor shallow impurity in a cylindrical GaAs–Ga 0.6Al 0.4As quantum well wire (QWW) as a function of the wire radius, the impurity position, and an applied magnetic field. The model considers an infinite length QWW with a finite radial confining potential and the presence of a uniform magnetic field applied parallel to the wire axis. The 1s-, 2p +-, 2p −-, 3p +-, 3p −-like impurity states are considered using the effective-mass approximation within the variational approach. We have found that for the 1s-like state the impurity binding energy increases with the magnetic field for impurity positions close to the center of the wire, but diminishes for on-edge impurities highlighting the competition between the geometrical and magnetic confinement. Also, our results shows that the 2p +-, 2p −-, 3p +-, 3p −-like excited states are not bounded in QWW with small radius, radius which diminishes with the applied magnetic field. We have observed that for high magnetic fields the localization of the wave function in the radial direction is higher for smaller values of the principal quantum number n. Our results are in good agreement with previous theoretical reports, with lower binding and transition energies than those which use infinite confinement potential, as expected.