Raman scattering analysis of relaxed GexSi1−x alloy layers

Abstract

We have used Raman scattering to evaluate thick epitaxial GexSi1−x layers with 0.20≤x≤0.43 grown on Si (100) substrates. We show that a detailed consideration of the composition dependencies of the relative intensities of the various phonon modes can enhance the sensitivity of Raman scattering to variations in composition and strain. We find that samples are uniform on a scale of ≂1 μm laterally and <1000 Å in the growth direction.

Composition and strain in thin Si1−xGex virtual substrates measured by micro-Raman spectroscopy and x-ray diffraction

“…As was mentioned above, considerable uncertainty exists as to where the baseline of a peak begins and where it ends. Mooney et al 34 found the integrated intensities ratios to be in good agreement with Eqs. ͑16͒ and ͑17͒ only if the peak at 430 cm −1 is included in the intensity of the Si-Ge mode, while in this work all local Si-Si peaks were excluded from the calculation of I Si-Ge and I Si-Si .…”

“…9,10,18 As was stated in Ref. 34, the localized Si-Si peaks were included in the measurement of integrated intensity of the Si-Ge mode. In this investigation, the intensity of the Si-Ge mode was measured excluding the peaks at 430 and ϳ450 cm −1 and the area of the Ge-Ge peak was estimated by excluding the long wings on both sides of the curve ͑see black dashed baseline in Fig.…”

Raman characterization of strain and composition in small-sized self-assembled Si/Ge dots

“…20. The b Ge-Ge value of Ϫ400 cm Ϫ1 for x Ge Ͼ0.55 is very close to the value reported for bulk Ge by Cerdeira et al 27 Besides the intensity ratio of the Ge-Ge and Si-Si modes, that of the Ge-Ge and Ge-Si (I Ge-Si ) modes is also used to determine the Ge content in Ge/Si alloys and nanostructures by the following equation, 23,25,28 …”

High Resolution X-ray Reciprocal Space Mapping

“…In the case of graded SiGe layers [12][13][14][15][16][17][18][19], the strain analysis is complicated since the RELP positions are different for different sublayers and the averaged strains depend on the position z along growth direction. In order to determine • the averaged strains in graded layers, both (004) and (224) reciprocal space maps (RSM's) have to be analyzed.…”