In-plane optical anisotropy of InGaN/GaN quantum disks in nanowires investigated by reflectance difference spectroscopy

The in-plane optical anisotropy (IPOA) of c-plane InGaN/GaN quantum disks (Qdisks) in nanowires grown on MoS₂/Mo and Ti/Mo substrates is investigated using reflectance difference spectroscopy (RDS) at room temperature. A large IPOA related to defect or impurity states is observed. The IPOA of samples grown on MoS₂/Mo is approximately one order of magnitude larger than that of samples grown on Ti/Mo substrates. Numerical calculations based on the envelope function approximation have been performed to analyze the origin of the IPOA. It is found that the IPOA primarily results from the segregation of indium atoms in the InGaN/GaN Qdisks. This work highlights the significant influence of substrate materials on the IPOA of semiconductor heterostructures.