Subband characteristics of Si δ-doped pseudomorphic In_(0.2)Ga_(0.8)As/GaAs heterostructures

摘要

Subband properties of Si δ-doped pseudomorphic In_(0.2)Ga_(0.8)As/GaAs heterostructures have been investigated by solving the Schrodinger-Kohn-Sham equation and the Poission equation self-consistently, and by the density-density dynamical response function. Different δ-doping configurations, in which the same Si δ-doped layer is placed at different positions with respect to the In_(0.2)Ga_(0.8)As well, have been studied to find their effect on subband electron densities and mobilities. High electron densities of greater than 3.6×10~(12) cm~(-2) are obtained when a δ-doping density of 4.5×10~(12)cm~(-2) is placed at the well center or at the well-barrier interface. However, the electron density in the well for Si δ-modulation-doped In_(0.2)Ga_(0.8)As/GaAs heterostructure is only about 1.3×10~(12)cm~(-2). The change of the position of a Si δ-doped layer from the well center to the barrier does not change the mobility of electrons in the lowest subband significantly. The Si δ doping in both barriers leads to an increase of the electron density by almost a factor of 2. The mobilities in the well for the modulation-doped structures are always much greater than those for the well-doped structures. The calculated results are also compared to the corresponding experimental data.