High-resolution x-ray diffraction investigation of relaxation and dislocations in SiGe layers grown on (001), (011), and (111) Si substrates

Abstract

This work presents a detailed characterization, using high-resolution x-ray diffraction, of multilayered Si1-xGex heterostructures grown on (001), (011), and (111) Si substrates by reduced pressure chemical vapor deposition. Reciprocal space mapping has been used to determine both the strain and Ge concentration depth profiles within each layer of the heterostructures after initially determining the crystallographic tilt of all the layers. Both symmetric and asymmetric reciprocal space maps were measured on each sample, and the evaluation was performed simultaneously for the whole data set. The ratio of misfit to threading dislocation densities has been estimated for each individual layer based on an analysis of diffuse x-ray scattering from the defects.

Tailoring thermal conductivity by engineering compositional gradients in Si1−x Ge x superlattices

“…The upper (blue) curve corresponds to the experimental data, and the bottom (red) curves correspond to the best fit. The narrow satellites are characteristic of the vertical correlation and sharp definition of the interfaces between repeated slabs in the multilayer structure [29]. Reasonable matches were obtained for the various multi-layered structures, consisting of four repetitions with the parameters shown in Table 1.…”

Thermal Stability of Thin Compressively Strained Ge Surface Channels Grown on Relaxed Si0.2Ge0.8Reverse-Graded Buffers

“…Moreover, the technique also allowed corrections to account for tilt which may occur in relaxed and partially relaxed layers. 31,32 The degree of relaxation, R, of the strained Ge channel with respect to the Si 0.2 Ge 0.8 buffer, was defined according to:…”

X-ray diffraction study of plastic relaxation in Ge-rich SiGe virtual substrates

“…10,12 The x-ray scattering theory has been also extended to epitaxial films consisting of layers with different composition and relaxation degree, and to graded layers. [13][14][15][16][17] These works use additional approximations that simplify the scattering intensity calculation. Particularly, they assume that dislocations of only one type (the 60 • dislocations) are present in the film and that the positional correlations are absent.…”