Tuning the optoelectronic properties of GaAs/AlxGa1−xAs core/shell tetrapod quantum dots with a single dopant

Abstract

This study investigates the optical properties of a novel core–shell tetrapod nanostructure composed of a GaAs core and an Al${}_x$Ga${}_{1-x}$As shell. Our focus is on understanding how its shape, geometry, and external factors influence its optical evolution. The aluminum concentration, $x$, within the shell serves as a crucial parameter, directly controlling the confinement well depth, and our analysis employs the finite element method (FEM). Specifically, we investigated the influence of dopant position along the ($Oz$) axis and aluminum concentration on the first three energy levels. We found that increasing the dopant distance from the electron and raising the aluminum concentration both contribute to an increase in the energy levels, attributed to a deeper confinement well. Additionally, we examined the linear, non-linear, and total optical absorption coefficient (OAC) and total refractive index change (RIC) for the two low-lying energy transitions 1$\to$2 and 2$\to$3. The results reveal a blueshift and a decrease in amplitude for the 1$\to$2 transition as the aluminum concentration increases. Expanding on previous experimental results, this research highlights the potential of these structures for groundbreaking applications in nanoelectronics and next-generation solar cells.