Strain Release in GaN Epitaxy on 4° Off‐Axis 4H‐SiC

Abstract A hybrid field‐effect transistor (HyFET), superior for power electronic applications, can be created by harnessing the merits of two representative wide‐bandgap semiconductors, gallium nitride (GaN) and silicon carbide (SiC). Yet, the incompactness in the epitaxy techniques hinders the development of the HyFET—GaN is usually grown on on‐axis foreign substrates including SiC, whereas SiC homoepitaxy prefers off‐axis substrates. This work presents a GaN‐based heterostructure epitaxially grown on a conventional 4° off‐axis 4H‐SiC substrate, which manifests its high quality and suitability for constructing GaN‐based high‐electron‐mobility transistors, thereby suggesting a practical approach to realizing HyFETs. In the meanwhile, a distinct two‐step biaxial strain‐relaxation process is proposed and studied with comprehensive characterizations.