Exploring near-perfect environments for quantum devices: Strain mapping in dislocation-free SiGe grown by lateral selective epitaxy

We propose to employ Scanning X-ray Diffraction Microscopy to acquire microscopic maps of the lattice deformations in dislocation-free SiGe layers grown by lateral selective epitaxy on a Silicon-on-insulator substrate. These samples utilize an aspect-ratio dislocation trapping mechanism and are to serve as near-perfect SiGe virtual substrates, which are required for the housing of sensitive quantum devices such as spin qubits. The main goals are to map the spatially-dependent tensors of lattice strain and rotation as well as any gradients in the SiGe alloy composition. This data would provide insight into the mechanisms of lateral epitaxy and the associated anisotropic plastic relaxation, allowing better control of the complicated deposition procedure and the fabrication of larger dislocation-free regions. The results will help provide a path towards the up-scaling of quantum devices as well as the development of mechanical modells for the description of laterally grown thin films.