Enhanced optical absorption of gradient-component AlxGa1-xAs nanowire arrays for solar cell applications

In this study, we numerically investigate the light capture performance of AlxGa1-xAs nanowires with gradient Al composition by utilizing COMSOL multiphysics based on finite element method (FEM). Different Al component ranges and sublayer thickness distributions along the axial direction of nanowire are considered. The simulation results show that the optical structure design of AlxGa1-xAs with a composition range varying from 0 to 0.4 show a better optical absorption ability compared with other composition range configurations. Besides, for AlxGa1-xAs nanowires with Al composition varying from 0 to 0.4 and 0 to 0.8, the absorptance of the structure with increasing sub-layer thickness from bottom to top is higher than that of the uniform thickness structure, while the structure with a decreasing thickness owns the worst performance. For AlxGa1-xAs nanowire arrays, the maximum optical absorption can be obtained when the incident light angle is 60 degrees. The design principle proposed in this work would provide a reference for selecting appropriate parameters in the application of solar cells.