Investigation of in-situ strain modulated Ge microstructures for a tunable on-chip laser

We propose to use the LAUEMAX instrument on BM32 to map the distribution of the strain tensor in Ge microbridges, as a function of the applied heat distribution and initial strain tensor distribution (i.e. uniaxial or biaxial strain, stress orientation, maximum strain amplitude…). The combination with the rainbow-filter technique will provide a quantitative strain measurement at relevant locations, to be compared with the Raman measurements. This series of experiments will bring a solid and complementary proof of giant strain modulation in our samples. Indeed, up to now this effect is only evaluated in an indirect fashion via Raman spectroscopy (see in the following). This experiment can be expanded in a close future to the case of GeSn, a forefront group four alloy for optoelectronics, with the ambitious goal to realize the first ultra wide band, wavelength tuneable, group four laser.