DFXM study of the coalescence of GaN nanopillars grown by Nano-Pendeo Epitaxy

An original method of compliant epitaxy, Nano-Pendeo Epitaxy, has been developed for achieving low dislocation density GaN and managing the strain in the nitride layers. Initial thin AlN and GaN layers are grown on silicon on insulator (SOI) layers, before being patterned into nano-pillars. The degrees of freedom in rotation acquired by the nano-pillars allow the crystallites to realign crystallographically at the time of coalescence, without creating any defects. This alignment is explained by a reduction of interface energy between adjacent crystallites. To go further in the mechanisms at work and feed our numerical simulations, we would like to perform Dark Field X-ray Microscopy (DFXM). The large field of view (FoV) of the microscope shall allow us to statistically measure over a large number of pillars, while the fine spatial and angular resolution of the microscope shall allow to systematically study the structural differences between the center and the border of each pillar.