Electronic States in Diffused Quantum Wells

TL;DR

This study calculates electronic states in diffused quantum wells using advanced models, revealing how diffusion length affects energy transitions and aligning well with experimental data.

Contribution

It introduces a detailed calculation of electronic states in diffused quantum wells using the empirical tight-binding model and Green function method, highlighting the impact of diffusion length on energy transitions.

Findings

Transition (C3-HH3) is insensitive to diffusion length for L_D=20-100 Å.

Transitions (C1-HH1), (C1-LH1), (C2-HH2), (C2-LH2) show large blue shifts as L_D increases.

Transitions (C1-HH1) and (C1-LH1) are less sensitive to L_D changes than (C3-HH3).

Abstract

In the present study we calculate the energy values and the spatial distributions of the bound electronic states in some diffused quantum wells. The calculations are performed within the virtual crystal approximation, $sp^3 s^*$ spin dependent empirical tight-binding model and the surface Green function matching method. A good agreement is found between our results and experimental data obtained for AlGaAs/GaAs quantum wells with thermally induced changes in the profile at the interfaces. Our calculations show that for diffusion lengths $L_{D}=20\div100$ {\AA} the transition (C3-HH3) is not sensitive to the diffusion length, but the transitions (C1-HH1), (C1-LH1), (C2-HH2) and (C2-LH2) display large "blue shifts" as L_{D} increases. For diffusion lengths $L_{D}=0\div20$ {\AA} the transitions (C1-HH1) and (C1-LH1) are less sensitive to the L_{D} changes than the (C3-HH3) transition. The observed dependence is explained in terms of the bound states spatial distributions.