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Technique for measuring the residual strain in strained Si/SiGe MOSFET structures using Raman spectroscopy

Lookup NU author(s): Dr Piotr Dobrosz, Professor Steve BullORCiD, Dr Sarah Olsen, Professor Anthony O'Neill


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A measurement technique for studying the strain in Si/SiGe layers has been developed based on Raman spectroscopy using a laser microprobe. The Si/SiGe layers were grown by ultra-low pressure chemical vapour deposition in a modified molecular beam epitaxy system. The structures consisted of a strained Si grown on relaxed Si1-xGex (x = 0.1, 0.15 ... 0.35), where the Si channel thickness was varied between 5 and 10 nm. Raman spectroscopy using a 514 nm laser indicated a significant shift in the Si peak from the SiGe layer; the position of this peak is related to the strain in the layer and strongly depends on Ge content, decreasing with increasing Ge in the virtual substrate. However, the strained Si peak shows a considerable overlap with the Si in SiGe peak and is difficult to deconvolute by conventional peak fitting approaches. The residual strain in the thin heterostructure Si/SiGe layers was, therefore, investigated before and after selectively etching the Si. The strain in the channel increased with Ge content in the under-lying SiGe as expected, confirming that the high-temperature device processing did not degrade the channel macrostrain.

Publication metadata

Author(s): Dobrosz P, Bull SJ, Olsen SH, O'Neill AG

Publication type: Conference Proceedings (inc. Abstract)

Publication status: Published

Conference Name: 4th European Symposium on NanoMechanical Testing

Year of Conference: 2004

Pages: 340-344

ISSN: 0044-3093

Publisher: Zeitschrift fuer Metallkunde