Stress generation and relaxation in (Al,Ga)N/6H-SiC heterostructure grown by plasma-assisted molecular-beam epitaxy

Abstract

In situ stress generation and relaxation in Al_0.25Ga_0.75N/GaN/AlN heterostructure with an overall thickness exceeding 3 μm in the process of its growth on a 6H-SiC substrate by low-temperature plasma-assisted molecular-beam epitaxy at substrate temperatures ranging from 690 to 740°C was studied. At room temperature, AlN and GaN layers revealed residual compressive stresses of–2.3 and–0.1 GPa, respectively. This made it possible to avoid cracking during postgrowth cooling of the structure.