非对称双势垒结构中电子态的特异性

Extraordinary Properties of Electronic States in An Asymmetric Double Barrier Structure

在包络波函数近似下自洽计算了非对称双势垒结构（ＤＢＳ）中的电子态，并正确得到了积累区和中央势阶中准束缚能级Ｅａｃ、Ｅｗｅ随偏压变化的反交叉过程．结果首次揭示了如果适当选取ＤＢＳ的入射垒厚度，随着外加电场不断增加，在过共振区积累层势阱和中央势阱会统一成一个大三角势阱的基态能级Ｅｃｏｍ，Ｅｃｏｍ具有很好的二维性，这表明在过共振区ＤＢＳ在入射端积累区中只存在二维电子．

Abstract 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.Our calculation verifies,for the first time,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,our calculation verifies that there exist only two dimensional electrons in the accumulation layer of the DBS as biased beyond resonance.