Formation and Properties of Locally Tensile Strained Ge Microstructures for Silicon Photonics
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The formation and properties of locally tensile strained Ge microstructures (“microbridges”) based on Ge layers grown on silicon substrates are investigated. The elastic-strain distribution in suspended Ge microbridges is analyzed theoretically. This analysis indicates that, in order to attain the maximum tensile strain within a microbridge, the accumulation of strain in all corners of the fabricated microstructure has to be minimized. Measurements of the local strain using Raman scattering show significant enhancement of the tensile strain from 0.2–0.25% in the initial Ge film to ~2.4% in the Ge microbridges. A considerable increase in the luminescence intensity and significant modification of its spectrum in the regions of maximum tensile strain in Ge microbridges and in their vicinity as compared to weakly strained regions of the initial Ge film is demonstrated by microphotoluminescence spectroscopy.
This study was partially performed in the framework of the State assignment for the Institute for Physics of Microstructures, Russian Academy of Sciences (theme no. 0035-2014-0201). The study was supported by the Russian Foundation for Basic Research (project no. 16-29-14056-ofi_m). Measurements were carried out using equipment of the Stand “Femtospectrum” of Center “Physics and technology of micro- and nanostructures” at the Institute for Physics of Microstructures.