Carrier recombination and diffusion in nitride materials have been extensively studied on a macroscopic scale and linked to various sample characteristics, including quantum well width, alloy composition, dislocation density, and overall efficiency. However, the precise mechanisms by which V-defect size, morphology, and local environment affect carrier diffusion and recombination remain unclear. With the rise of high-precision micro-scale optoelectronics, where defect impact is most pronounced, it is crucial to analyze these defects at the nanoscale and in real time. This study aims to provide an up-close examination of V-defects, which naturally form in InGaN, by employing time-resolved cathodoluminescence (TRCL) to obtain transient nanoscale CL profiles of dislocation-induced defects, enabling a deeper understanding of carrier behavior within and around them. The main objective is to profile transient times and cathodoluminescence intensity in relation to defect size. Transient times were extracted by capturing luminescence decay both in areas unaffected by the defect and along the defect’s geometry on the same axis. First, a broad-area CL and SEM scans of the sample were performed. Then, measurements of similarly sized defects within InGaN samples were conducted, capturing intensity and time variations, along with CL maps and SEM images of individual defects. After data processing, the extracted parameters were used to visualize profiles of individual defects and defect groups of similar sizes. Depending on size and other potential factors, V-defects are known to influence sample properties in a dual way. The results reveal that larger defects enhance carrier diffusion length, but at the same time, they introduce non-radiative recombination channels, reducing overall efficiency. In some cases, however, V-defects have been observed to screen dislocations, mitigating their negative effects on non-radiative recombination.
By analyzing measured transient times and intensity trends—such as intensity drop and faster transients—defect profiles were evaluated based on two key factors: [1] the depth of the profile, reflecting the contrast of each parameter inside and outside the defect, and [2] luminescence variations across the defect structure. For future work, full TRCL maps would enable a more detailed analysis of carrier lifetime and luminescence intensity by capturing decay dynamics and intensity variations fully in a selected area of the sample. Resolving carrier dynamics at the defect level would offer advances for defect-engineered optoelectronics, key insights for optimizing micro-LEDs, quantum wells, and next-generation GaN-based devices.