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We show that a strong tensile strain can be applied to germanium microdisks using silicon nitride stressors. The transferred strain allows one to control the direct band gap emission that is shifted from 1550 nm up to 2000 nm, corresponding to a biaxial tensile strain around 1%. Both Fabry-Perot and whispering gallery modes are evidenced by room temperature photoluminescence measurements. Quality factors up to 1350 and limited by free carrier absorption of the doped layer are observed for the whispering gallery modes. We discuss the strain profile in the microdisks as a function of the disk geometry. These tensile-strained microdisks are promising candidates to achieve Ge laser emission in compact microresonators. V

In this work we study, using experiments and theoretical modeling, the mechanical and optical properties of tensile strained Ge microstructures directly fabricated in a state-of-the art complementary metal-oxide-semiconductor fabrication line, using fully qualified materials and methods. We show that these microstructures can be used as active lasing materials in mm-long Fabry-Perot cavities, taking advantage of strain-enhanced direct band gap recombination. The results of our study can be realistically applied to the fabrication of a prototype platform for monolithic integration of near infrared laser sources for silicon photonics.

We have analyzed the strain distribution and the photoluminescence in Ge microstructures fabricated by means of a Si-CMOS compatible method. The tensile strain in the Ge microstructures is obtained by using a SiN stressor layer. Different shapes of microstructure, allowing the Ge layers to freely expand into one, two, or three dimensions, resulted in different strain distribution profiles. Maximal equivalent biaxial tensile strain values up to ~0.8% have been measured. Room temperature photoluminescence emission has been observed and attributed to direct-band gap recombination spectrally shifted by tensile strai