Donor transition energies and their line strengths in GaAs/${\mathrm{Al}}_{\mathrm{x}}$${\mathrm{Ga}}_{1\mathrm{-}\mathrm{x}}$As quantum-well structures in the presence of a magnetic field applied parallel to the interfaces

We have calculated the transition energies between the ground state (1s-like) and three excited states (2s-, 2$p_y$-, and 2$p_z$-like) of a hydrogenic donor associated with the first subband in a GaAs quantum well sandwiched between two semi-infinite layers of ${\mathrm{Al}}_{\mathrm{x}}$ ${\mathrm{Ga}}_{1\mathrm{-}\mathrm{x}}$As in the presence of a magnetic field applied parallel to the interfaces. In addition, we have also calculated the line strengths of these transitions in various polarizations. Results have been obtained both as a function of the applied magnetic field and the position of the donor ion along the direction of growth. We have followed a variational approach in which the trial wave functions are expanded in terms of appropriate Gaussian basis sets.