To improve the quality of a strained Si layer on a SiGe virtual substrate, the distribution of dislocations in a graded SiGe layer was characterized using electron beam induced current. A crosshatch pattern of dark and bright bands running along the two <110> directions was observed in an electron beam induced current electron beam induced current image taken with a 25keV-electron beam at 80K. These dark and bright electron beam induced current bands were attributed, respectively, to high- and low-density dislocation regions in the graded SiGe layer, as was confirmed by transmission electron microscopy. The effects of such an inhomogeneous dislocation distribution on the surface morphology and the generation of misfit dislocations at the interface of strained Si/SiGe were investigated. Comparison between the electron beam induced current image and an atomic force microscope image showed that the high-density dislocation regions were correlated with ridges on the surface topography. A chemical etching image showed that most of the misfit dislocations lay along the edges of surface ridges. Possible mechanisms of misfit dislocation generation at the interface of the strained Si/SiGe were proposed.

Inhomogeneous Distribution of Dislocations in a SiGe Graded Layer and its Influence on Surface Morphology and Misfit Dislocations at the Interface of Strained Si/Si0.8Ge0.2. X.L.Yuan, T.Sekiguchi, J.Niitsuma, Y.Sakuma, S.Ito, S.G.Ri: Applied Physics Letters, 2005, 86[16], 162102 (3pp)