Nanoscale Mapping of the Full Strain Tensor, Rotation, and Composition in Partially Relaxed InxGa1-xN Layers by Scanning X-ray Diffraction Microscopy

Strain and composition play a fundamental role in semiconductor physics, since they are means to tune the electronic and optical properties of a material and hence develop alternative devices. Today it is still a challenge to measure strain in epitaxial systems in a nondestructive manner, which becomes especially important in strain-engineered devices that often are subjected to intense stress. In this work, we demon-strate a microscopic mapping of the full tensors of strain and lattice orientation by means of scanning x-ray diffraction microscopy. We develop a formalism to extract all components of strain and orientation from a set of scanning diffraction measurements and apply the technique to a patterned InxGa1-xN double layer to study strain relaxation and indium incorporation phenomena. The contributions due to varying indium content and threading dislocations are separated and analyzed.