Ultra-thin strain relaxed SiGe buffer layers with 40% Ge


Virtual substrates with ultra-thin SiGe strain relaxed buffers have been grown on Si substrates by a method employing point defect supersaturation in the growing layers. A concept of the point defect influence on the strain relaxation and on defect interactions in layers has been proposed. A method is developed to increase the degree of relaxation in sub-100 nm SiGe buffer layers and to provide a smooth surface morphology. Layer growth has been realized by solid source molecular beam epitaxy in a chamber equipped with an in situ monitoring system. One of the growth stages, performed at a very low temperature, serves the generation of point defects. Strain relaxation tunable up to the high degree and a crosshatch-free surface morphology are demonstrated in 40nm thick SiGe buffers which contain 40-45% Ge.

Growth monitoring enables the control of the process window and the layer crystallization by a chosen mechanism.

Virtual substrates produced by the described method were successfully tested in nMODFET structures.

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Authors thank Deutsche Forschungsgemeinschaft for financial support (project KA 1229/5-3).

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Correspondence to Klara Lyutovich.

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Lyutovich, K., Kasper, E. & Oehme, M. Ultra-thin strain relaxed SiGe buffer layers with 40% Ge. MRS Online Proceedings Library 809, 14 (2003). https://doi.org/10.1557/PROC-809-B1.4

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