LEVEL WIDTH OF A QUASI-BOUND STATE IN A DOUBLE-BARRIER PARABOLIC-WELLRESONANT-TUNNELING STRUCTURE

Taking exact Airy functions and Hermitian functions as envelope functi ons, we investigate in detail the level width of a quasibound state fo r electrons coherent resonant tunneling through symmetric and asymmetr ic double-barrier parabolic-well resonant tunneling structures (DBRT) with the transfer-matrix formalism. It is found that for the symmetric structure and the asymmetric structure with left barrier thicker than the right one, both the level width and the peak value vary monotonou sly with increasing applied bias, but for the asymmetric DBRT structur e with left barrier thinner than the right one, they change nonmonoton ously. The nonmonotonous variations of the level width and the peak va lue reflect the transition of tunneling type (i.e. first from incomple tely resonant tunneling to completely resonant tunneling, and then fro m completely resonant tunneling back to incompletely resonant tunnelin g). The effects of well width, barrier thickness and barrier height on the level width and the peak value are also inspected.