RBS and XRD analysis of SiGe/Ge heterostructures for p-HMOS applications

Si/SiGe graded buffer 6 mu m/Si1.4Ge0.6 2 mu m (CVD)/Si0.4Ge0.6 200 nm (MBE)/Ge t/Si0.4Ge0.6 20 nm/Si 2 nm heterostructures with Ge channel thicknesses t = 16 nm and 20 nm were grown by a method of hybrid epitaxy and annealed ex situ at 650 degrees C under dry N-2. As grown and annealed samples were measured using Rutherford backscattering. The H-1 experiments at different proton energies allowed 4 the thick linearly graded SiGe buffer to be analysed along with the uniform SiGe layer terminating the linearly graded region. He grazing angle experiments were sensitive to the thinner top layers, enabling the Ge channel thickness, composition and roughness to be determined. However, the depth resolution at the Ge channel was not good enough to determine if the channel layer consisted of pure Ge, or contained a residual Si content (few at.%), inherent to the method of growth. Complementary X-ray diffraction reciprocal space maps led to a high accuracy (similar to 1%) determination of the Si content of the channel, as well as the strain. Other layers in the structure were also accessible. Cross sectional transmission electron microscopy (XTEM) was also performed. In this paper we show how the combination of all these techniques leads to the complete structural characterization of these samples. (c) 2006 Elsevier B.V. All rights reserved.