Lithographically defined low dimensional SiGe nanostripes as silicon stressors

The introduction of strain in semiconductors is a well-known technique for increasing their conductivity and thus for enhancing the performance of silicon-based electronic devices. In the present work, we investigate the strain induced in the Si substrate by linear SiGe/Si structures with a width less than 100 nm. By varying the Ge content and geometrical parameters, it is possible to maximize the strain in the Si substrate without detrimental plastic relaxation in the SiGe stripes. The structures were defined by electron-beam lithography from strained SiGe deposited epitaxially by low-energy plasma-enhanced chemical vapor deposition. The strain in the heterostructures has been characterized by a combination of finite-element modeling, x-ray diffraction, and ?Raman spectroscopy techniques. We show that nano-patterning induces an anisotropic strain relaxation in the SiGe stripe with a simultaneous strong compression of the Si substrate. © 2012 American Institute of Physics.