Microscopic mapping of strain and lattice orientation on InGaN pseudo-substrates for micro-LEDs

The objective of this study is to obtain a microscopic mapping of the full tensors of strain and lattice orientation on three types of InGaN samples, which are competitive candidates to produce pseudo-substrates for InGaN red micro-LEDs. The first type of samples contains InGaN platelets on InGaN nanowirebased seeds. The main point here is to verify the similarity of one platelet to another in term of composition and lattice orientation. The second type of samples is an In-enriched InGaN layer on a porosified InGaN layer. The crucial point here is to determine if the porosification of the InGaN underlayer leads to inhomogeneity of the strain or the lattice orientation of the In-enriched InGaN upper layer. The third type of sample consists in an InGaN layer stretched on a polymer and transferred to a sapphire substrate. In this case, it is essential to check the strain and rotation fields due to eventual edge and screw threading dislocations after the stretching of the InGaN layer.