Adverse Effects of Stacking Mismatch Boundaries on GaN Optoelectronic Properties

Understanding and establishing the relationship between the defect and macroscopic characteristics is crucial for materials. It is great challenge for linking atomic-scale defect structures to device performance owing to the difficulty in isolating single-type defects in a material. In this work, single-crystal and twin-structured GaN nanowires are prepared, and the performance of photodetectors based on two types of nanowires differs by two order of magnitude. Through analysis of the microstructure at the atomic scale, it is revealed that this difference in performance is due to the presence of unique disconnection structure in the twin nanowires. The embedded dual stacking faults at the disconnection position will introduce stacking mismatch boundaries in the crystal. Combining density functional theory calculations, it is revealed that the stacking mismatch boundary generates deep defect states in the band structure, which explains the performance degradation caused by the { $10\overline{1}3$ } twin boundary.