Local strain distribution analysis in strained SiGe spintronics devices

This paper reports nanobeam X-ray diffraction (nanoXRD) measurement results for strained SiGe spintronics devices grown by molecular beam epitaxy. A quantitative nanoXRD analysis verifies that in-plane strain is properly exerted on the SiGe spin channel layer in the device showing enhanced spin diffusion length, whereas overall strain relaxation and local change in crystallinity occur in the sample with unclear spin signals. Crystal defects such as dislocations and stacking faults found in cross-sectional transmission electron microscopy observations are correlated with the results of nanoXRD analysis and their influence on spin transport properties are discussed. The present results demonstrate the capability of the nanoXRD based method for quantitative nondestructive analysis of strain distribution and crystallinity in real device structures.