Electronic and hole minibands in quantum wire arrays of different crystallographic structure

TL;DR

This study investigates how the electronic and hole minibands in GaAs/AlGaAs quantum wire arrays are affected by lattice geometry, material composition, and structural parameters, with implications for solar cell efficiency.

Contribution

It provides a comparative analysis of electronic and hole minibands in square and triangular lattice quantum wire arrays using effective-mass approximation.

Findings

Minigaps are wider at low lattice constants in triangular lattices.

At high lattice constants, square lattices exhibit wider minigaps.

Lattice geometry significantly influences miniband structure and solar cell performance.

Abstract

We consider quantum wire arrays consisting of GaAs rods embedded in Al$_{x}$Ga$_{1-x}$As and disposed in sites of a square or triangular lattice. The electronic and hole spectra around the conduction band bottom and the valence band top are examined versus geometry of the lattice formed by the rods, concentration of Al in the matrix material, and structural parameters including the filling fraction and the lattice constant. Our calculations use the envelope function and are based on the effective-mass approximation. We show that the electronic and hole spectra resulting from the periodicity of the heterostructure, depend on the factors considered and that the effect of lattice geometry varies substantially with lattice constant. For low lattice constant values the minigaps are significantly wider in the case of triangular lattice, while for high lattice constant values wider minigaps occur in the square lattice-based arrays. We analyse the consequences of our findings for the efficiency of solar cells based on quantum wire arrays.