Localized thinning for strain concentration in suspended germanium membranes and optical method for precise thickness measurement

P. O. Vaccaro, M. I. Alonso, M. Garriga, J. Gutiérrez, D. Peró, M. R. Wagner, J. S. Reparaz, C. M. Sotomayor Torres, X. Vidal, E. A. Carter, P. A. Lay, M. Yoshimoto, A. R. Goñi

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2 Citations (Scopus)

Abstract

© 2018 Author(s). We deposited Ge layers on (001) Si substrates by molecular beam epitaxy and used them to fabricate suspended membranes with high uniaxial tensile strain. We demonstrate a CMOS-compatible fabrication strategy to increase strain concentration and to eliminate the Ge buffer layer near the Ge/Si hetero-interface deposited at low temperature. This is achieved by a two-steps patterning and selective etching process. First, a bridge and neck shape is patterned in the Ge membrane, then the neck is thinned from both top and bottom sides. Uniaxial tensile strain values higher than 3% were measured by Raman scattering in a Ge membrane of 76 nm thickness. For the challenging thickness measurement on micrometer-size membranes suspended far away from the substrate a characterization method based on pump-and-probe reflectivity measurements was applied, using an asynchronous optical sampling technique.
Original languageEnglish
Article number115131
JournalAIP Advances
Volume8
DOIs
Publication statusPublished - 1 Nov 2018

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