In-Situ mapping of structural aging in high-power GaN-on-Si devices

We propose to employ Scanning X-ray diffraction microscopy (SXDM), to investigate the spatial strain
distribution in functional high-power transistors based on epitaxial GaN layers deposited on Si(111)
substrates (GaN-on-Si). Spatial mapping of reciprocal space maps (RSMs) of three asymmetric Bragg
reflections will reveal the following features in the active layers: a) All components of the lattice strain
tensor and rotation tensor, b) presence of structural defects, such as threading (TD) and misfit
dislocations (MD), c) mechanical deformations induced by metal contacts within the semiconductor layers.
Moreover, we will investigate the same devices at different stages during a high temperature reverse bias
(HTRB) stress test to observe the structural evolution in the heterostructure during device lifetime.