Inference of Indium Competition on the Optical Characteristics of GaAs/InxGa1−xAs Core–Shell Nanowires with Reverse Type-I Band Alignment

One-dimensional GaAs/InGaAs core-shell nanowires (NWs) with reverse type-I band alignment are promising candidates for next-generation optoelectronic devices. However, the influence of composition gradients and atomic interdiffusion at the core-shell interface on their photoluminescence (PL) behavior remains to be clarified. In this work, GaAs/In<i>_x</i>Ga_1-<i>x</i>As NW arrays with different indium (In) compositions were prepared using molecular beam epitaxy (MBE), and their band alignment and optical responses were systematically investigated through power and temperature-dependent PL spectra. The experiments reveal that variations in the In concentration gradient modify the characteristics of potential wells within the composition graded layer (CGL), as reflected by distinct PL emission features and thermal activation energies. At elevated temperatures, carrier escape from these wells is closely related to the observed PL saturation and emission quenching. These results provide experimental insight into the relationship between composition gradients, carrier dynamics, and emission properties in GaAs/InGaAs core-shell NWs, making them promising candidates for high-performance nanoscale optoelectronic device design.