Extraordinary properties of electronic states in an asymmetric double barrier structure

A self-consistent calculation based on effective mass theory is presented to evaluate the electronic states in an asymmetric double barrier structure (DBS). The results correctly show an anticrossing between the quasibound level in the accumulation layer, Eac, and that in the central well, Ewe, as the applied bias is swept from pre-resonant to offresonant regions. The calculation verifies, that if a suitable thickness of the emitter barrier is adopted and the DBS is biased beyond resonance, the accumulation layer and the central well may combine into one large triangle-like potential well because the isolation effect of the emitter barrier is substantially reduced by increasing electric field. As a result, Eac and Ewe no longer separate from each other but combine, into one united level Ecom, i.e., the ground level in the large united well. Since Ecom is almost of pure two dimensionality, the calculation verifies that there exist only two dimensional electrons in the accumulation layer of the DBS as biased beyond resonance.