Raman mapping analysis of stress and dislocation defect correlation in GaN-on-Si epitaxial layers with and without superlattice structures

Abstract The correlation between stress distribution and dislocation defect concentration in GaN epitaxial layers grown on Si substrates, with and without a superlattice (SL) structure, was examined using Raman mapping. High-resolution x-ray diffraction (XRD), atomic force microscopy (AFM), and Hall effect measurements using the van der Pauw method were employed to evaluate the crystalline quality, surface morphology, and electrical properties. Raman mapping over an 80 × 80 μ m 2 area revealed that the GaN-on-Si sample with the SL structure exhibited uniform compressive stress, while the sample without the SL structure showed a mixture of compressive and tensile stresses with pronounced non-uniformity. XRD and AFM results confirmed a lower dislocation defect density in the SL-containing sample, accompanied by higher carrier mobility. These results demonstrate that incorporating an SL structure effectively improves both the structural and electrical quality in GaN-on-Si epitaxial layers, while Raman mapping serves as a fast and reliable approach for evaluating material uniformity and optimizing wafer-scale GaN-on-Si growth processes.