Elucidating proper framework for determination of threading dislocation densities in semiconductor films: a comprehensive study based on Ge/Si(001)

Abstract Method of deducing threading dislocation densities (TDDs) from X-ray diffraction (XRD) peak widths has been reevaluated based on crystallography theories, and Ge/Si heteroepitaxial structures were taken as model materials for investigation. The procedure was tailored in accordance with the specific designs of modern XRD systems to minimize instrumental interference, while practical characteristics of heteroepitaxial films was also considered to avoid intrinsic errors. TDDs of samples grown with different epitaxy methods were investigated by using the newly implemented XRD method as well as etch pit density (EPD) method, and satisfactory agreement has been achieved among 3 independently calculated sets of TDD results: two from XRD and one from EPD. Those values were further corroborated by cross-sectional TEM analysis. Key considerations that are of scientific and technical importance in TDD studies were also discussed in detail. The current work has provided not only the most up-to-date elucidation on obtaining TDD values in semiconductor epitaxial films, but also insight into the long-existing ambiguity in TDD calculation methods, which will be helpful for future studies of defect density characterizations on various material systems.