Observation of structural defects in GaN/InGaN multi-quantum wells grown on semipolar (112¯2) substrate using cathodoluminescence in transmission electron microscopy.

This article focuses on the characterization of defect structures, specifically basal plane stacking faults (BSFs), in semipolar (11̅22) gallium nitride (GaN) thin films grown on m-plane sapphire substrates for light-emitting diode (LED) applications. Using transmission electron microscopy cathodoluminescence (TEM-CL), the study identifies and maps the distribution of three BSF types—I1, I2, and E—along with related partial dislocations (PDs) and prismatic stacking faults (PSFs), revealing that I1-BSFs are the most prevalent while I2-BSFs appear as thinner strips with lower density. The research highlights how these defects influence luminescence properties and surface morphology, with TEM-CL providing high spatial resolution to distinguish defect types and their optical signatures, which are challenging to resolve by conventional methods. The findings also discuss the impact of hemispherical patterned sapphire substrates (HPSS) on defect formation and suggest that this optical fingerprinting approach can aid in optimizing growth processes to improve LED efficiency on semipolar GaN films.