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Optical experiments on electric field tunable AlAs/GaAs coupled quantum wells clearly demonstrate that the optical nature of these structures can be directly controlled by an applied electric field. In this work we are concerned with calculation and analysis of the first electron and holOe states in these structures. We take into account the effects of the heterostrucuture geometry and of the external uniform electric field applied perpendicularly to the layers, which may lead to an anticrossing of low-lying electron levels in the system. Calculations are performed within the tight-binding supercell formalism with interactions between atomic orbitals up to second nearest-neighbors. Our results show that for GaAs layers less than 30 Å wide, application of electric fields takes the structures from typeII to type I heteroestructure behavior. Our estimated value of the electric field intensity needed to cause this transition is in good agreement with the experimental results for comparable heteroestructures geometries .

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.