Modelling of Strain Effects in Core/shell QDs with Tight Binding Theory and k.p Effective Mass Approximation

Abstract

Reliable predictions of the potential of nanoscale semiconductor heterostructures for nanodevice fabrication require accurate theoretical models and precise numerical calculations to assess how strain affects their electronic, optical and structural properties. The second nearest neighbour (2NN) sp3s* tight binding model and the four-band k.p effective mass approximation are employed to analyze impact of strain on the optical, electronic and structural properties in nanoscale spherical CdSe and ZnSe-based core/shell quantum dots (QDs) in this study. According to our analysis, when the shell diameter increases linearly, keeping the core diameter constant, core bandgaps increase parabolically in ZnSe/ZnS and CdSe/Cd(Zn)S QDs but decrease parabolically in ZnSe/CdS QDs. Furthermore, with a constant shell diameter, an increase in core diameter results in a parabolic decrease of core bandgaps in all four QD types. The proposed model can serve as an effective design tool for simulating nanoscale core/shell heterostructures in quantum dot-based nanodevices.