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A systematic study of the ground-state binding energies of a hydrogenic impurity in quantum dots subjected to external electric and magnetic fields is presented. The quantum dot is modeled by superposing a lateral parabolic potential and a square-well potential and the energies are calculated via a variational approach within the effective-mass approximation. The interplay between the confinement effects due to the applied fields and the quantum-size confinements on the binding energies is analyzed. The role played by the impurity position along the well direction on the impurity energies is also discussed. We have shown that by changing the strength of the external electric and magnetic fields, a large spread in the range of the donor binding energy may be obtained, for a particular choice for the lateral confinement. The presented results could be used to tailor energy states in optoelectronic devices.

Optical experiments on electric-field-tunable AlAs/GaAs heterostructures demonstrate that the optical nature of these structures can be directly controlled by an applied electric field. We present calculations performed within the tight-binding supercell formalism, taking into account the effects of the heterostructure geometry and of the external uniform electric field. We describe the temporal and spatial evolution of the relevant electronic states. The electric-field intensity needed to cause the indirect–direct transition is obtained in good agreement with the experimental results for comparable heterostructure geometry. We present simple and reliable expressions to estimate the switching time scales involved in such processes.

The effects of both electric and magnetic fields (applied perpendicular to the interfaces) on the donor transition energies on a GaAs‐Ga1−xAlxAs quantum well are studied by following a variational calculation within the effective‐mass approximation with two‐parameter variational envelope hydrogenic wave functions for the 1s‐ and 2p+‐like donor states. A detailed analysis of the far‐infrared intradonor absorption spectra, taking into account a proper consideration of the impurity‐doping profile, is performed and results are compared with recent experimental data. The agreement between the reported magnetospectroscopic data and the average photon energy at the width at half‐maximum of the calculated infrared‐absorption spectra is quite apparent. It is unambiguously shown that the absorption spectra must be evaluated with an adequate choice of the variational envelope wave function for a correct quantitative understanding of the experimental measurements.