In-situ strain relaxation of InGaN/GaN mesa measured by μLaue

For the development of efficient μdisplays, CEA-Leti is developing a new “InGaN” substrate. This new substrate is made of a 200 nm InGaN layer which is patterned into 5 μm mesas. The patterning allows strain relaxation of the InGaN layer, which is the main goal of this substrate. A previous macroscopic study, in our lab, of the In-plane lattice parameter versus temperature has enabled us to highlight that a second relaxation occurs during the annealing.This relaxation of the InGaN layer needs to be characterized at a sub-micron scale to better understand the mechanisms of this relaxation. In-situ strain relaxation of InGaN mesa measured by μ-Laue will help us to better understand the relaxation mechanisms just after the patterning and also what phenomena of relaxation locally happen during the annealing.μ- Laue in-situ with a beam size around 0.5 μm would appear to be the appropriate experiment to characterise and understand the relaxation of this InGaN layer.