Resonant tunneling in double-barrier parabolic well structures

The intrinsic time characteristics of a double-barrier parabolic well structure are studied numerically. One-dimensional structures with AlAs and AlGaAs barrier (and superlattice) material are investigated, and two models are considered: the actual microstructure (graded-superlattice) model and the parabolic-potential-well-model. Time-independent results such as quasi-energy levels and their widths are essentially the same for these two models. However, their time dependence has been found to be considerably different. Although the buildup times for these models are very close in magnitude, the onset of the exponential decay law for the resonant state in the parabolic potential well takes place in a very short time (after the electron density inside the well has reached its peak), thus allowing the time decay constant tau /sub d/ to be a good measure of the temporal decay.>