COUPLING BETWEEN NORMAL AND LATERAL DEGREES OF FREEDOM OF AN ELECTRONIN QUANTUM-WELLS AND SUPERLATTICES AT ZERO AND FINITE MAGNETIC-FIELDS

We present the effective-barrier-height method to investigate the effe cts of coupling between normal and lateral degrees of freedom of an el ectron in the parabolic conduction-band approach. This is performed on electronic states in quantum wells (QW's) and superlattices (SL's) at zero and finite magnetic fields perpendicular to interfaces. The nume rical calculations for GaAs/AlxGa1-xAs materials show that the couplin g effect leads not only to the shift of the sublevels in QW's and subb and, in SL's toward the well bottom with increasing k(xy) or n, but al so to the disappearance of high excited states close to the top of the barrier when k(xy) or n exceeds a certain value owing to the the fast lowering of the effective-barrier height. We also investigate the var iation of the shift of levels in QW's with the well width and found th at this coupling effect becomes more striking in thin QW's.