Investigation of two-dimensional electron gas concentration in selectively doped n-Al xGa 1− xAs/In yGa 1− yAs/GaAs heterostructures

Abstract

The two-dimensional electron gas (2DEG) concentration of the δ-doped Al x Ga 1− x As/In y Ga 1− y As/GaAs heterojunction for a variety of different configurations are investigated. The finite differential method to determine the 2DEG concentration, based on the self-consistent calculations of the Schrödinger and Poisson equations are described. The cases where the δ-doping is placed in the AlGaAs barrier (conventional heterojunction) and in a narrow quantum well within the AlGaAs barrier where the Al concentration in the well ( x Al well) is less than in the barrier ( x Al Barr) (novel heterojunction) are also examined. This is intended to reduce the effects of DX centres. To improve more the 2DEG concentration, the δSi in a narrow quantum well and the InGaAs layer introduced at the heterointerface between the AlGaAs and the GaAs are combined in only one structure. Further, other important paramerters of the system such as In mole fraction and thickness of InGaAs layer are studied. The variation trends of calculated 2DEG concentrations are in good agreement with the experimental results.