High-resolution x-ray reflection Fourier analysis of metamorphic Si/SiGe quantum wells

Graded buffer metamorphic epitaxial heterostructures are extraordinarily difficult to analyze using x-ray diffraction because of large signal contributions from the buffer. As an alternative, Fourier signal processing is applied to x-ray reflectivity data such that layer thickness and reflectivity strength are readily extracted. This analysis is applied to two strained silicon quantum wells grown inside relaxed silicon germanium barriers. Analysis of the x-ray reflectivity data directly determines that the quantum wells are 8.5 and 8.7 nm spaced by a 22.0-nm thick barrier. These values agree with those extracted from transmission electron microscopy to better than 0.5 nm.