Theoretical modelling of exciton binding energy, steady-state and transient optical response of GaN/InGaN/GaN and AlGaN/GaN/AlGaN core–shell nanostructures

Abstract

Here, we present an efficient 1D model to describe carrier confinement in GaN/InGaN/GaN and AlGaN/GaN/AlGaN core–shell nanostructures (CSNs) within the effective mass framework. A self-consistent procedure combined with hydrogenic model is implemented to estimate exciton binding energy in these CSNs, as a function of CSN dimensions, polarization charge and alloy composition. A 3-fold higher exciton binding energy in these CSNs than that in planar counterparts is attributed to an increased electron–hole overlap. The trend exhibited by the exciton binding energy with polarization charge and alloy composition in the two types of CSNs is significantly different, owing to a drastic difference in the piezoelectric polarizations. A detailed investigation of the steady-state and transient optical response from these CSNs suggests that GaN/InGaN/GaN CSNs emit a wide spectrum. However, that is not the case with AlGaN/GaN/AlGaN CSNs owing to a relatively weaker quantum confined Stark effect. This study is aimed at providing accurate design strategies for UV-blue III-N CSN light-emitting diodes.