High-temperature x-ray characterization of GaN epitaxially grown on Sc2O3/Y2O3/Si(111) heterostructures

The thermal behaviour of GaN epitaxially grown on a Sc2O3/Y2O3 bilayer buffer on the Si(1 1 1) substrate is studied between room temperature (RT) and 800 degrees C by x-ray diffraction of symmetrical and asymmetrical reflections. It is found that the GaN layer is in-plane mediated by the oxide buffer completely fixed to the Si substrate, which indicates the absence of any temperature related compliance behaviour of the oxide buffer. The GaN grows at 720 degrees C already slightly tensile strained on top of the larger Sc2O3 lattice, and this strain increases further during cooling down to RT due to different coefficients of thermal expansion of GaN and the Si substrate.