Nanoscale Raman mapping of elastic stresses in multilayer heterostructure based on multi-period GaN/AlN superlattices grown using HVPE technology on hybrid SiC/Si substrate

For the first time, a multilayer heterostructure consisting of periodically arranged GaN and AlN layers was formed by chloride-hydride gas-phase epitaxy on a SiC/Si hybrid substrate synthesised by the method of coordinated atom substitution. To level the difference in lattice parameters and thermal expansion coefficients between the epitaxial layers of the heterostructure and the hybrid substrate, an ensemble of multi-period GaN/AlN superlattices was formed. It is shown that only two main reasons made it possible to grow a heterostructure of a given thickness, low surface roughness of large-block upper GaN layer and without cracks. These reasons are: the special structure of the SiC/Si hybrid substrate and the creation of an ensemble of multi-period GaN/AlN superlattices between epitaxial layers. The study of the heterostructure using a set of string-spectroscopic methods, including nanoscale mapping of elastic stresses, unambiguously confirmed this conclusion and showed that the thicker such a structure, the less elastic stresses arise in the upper layers of GaN. At the same time, in SL2-type superlattices (with a constant period) located in the upper part of the structure, the stresses are practically absent. •A multilayer heterostructure consisting of GaN and AlN layers was formed by HVPE on a SiC/Si hybrid substrate.•Low surface roughness of large-block upper GaN layer without cracks.•The nanoscale Raman mapping of elastic stresses showed that the less elastic stresses arise in the upper GaN layer.