Nanoscale Structural and Emission Properties within “Russian Doll”-Type InGaN/AlGaN Quantum Wells

Due to the increasing desire for nanoscale optoelectronic devices with green light emission capability and high efficiency, ternary III-N-based nanorods are extensively studied. Many efforts have been taken on the planar device configuration, which lead to unavoided defects and strains. With selective-area molecular-beam epitaxy, new “Russian Doll”-type InGaN/AlGaN quantum wells (QWs) have been developed, which could largely alleviate this issue. This work combines multiple nanoscale characterization methods and k∙p theory calculations so that the crystalline structure, chemical compositions, strain effects, and light emission properties can be quantitatively correlated and understood. The 3D structure and atomic composition of these QWs are retrieved with transmission electron microscopy and atom probe tomography while their green light emission has been demonstrated with room-temperature cathodoluminescence experiments. k∙p theory calculations, with the consideration of strain effects, are used to derive the light emission characteristics that are compared with the local measurements. Thus, the structural properties of the newly designed nanorods are quantitatively characterized and the relationship with their outstanding optical properties is described. This combined approach provides an innovative way for analyzing nano-optical-devices and new strategies for the structure design of light-emitting diodes.