Optical Characteristic of the Strain-Controlled GaN Epitaxial Layer Grown on 6H-SiC Substrate by an Adapting (GaN/AlN) Multibuffer Layer

GaN epitaxial layers were grown on a (0001) 6H-SiC substrate by metalorganic vapor phase epitaxy by adapting a (GaN/AlN) multibuffer layer. Successful control of residual strain in the epitaxial layers was achieved by changing the layer structure of the (GaN/AlN) multibuffer layer. The lattice constant c of the thin GaN epitaxial layer (as thin as 0.1 μm) was close to that of freestanding GaN, where the thin GaN layer was grown on the substrate by adapting the multibuffer layer. In addition, the (GaN/AlN) multibuffer layer is effective not only for control of the residual strain included in a GaN epitaxial layer, but also for improving the quality of a GaN epitaxial layer.