Mid-infrared light emission > 3 µm wavelength from tensile strained GeSn microdisks

GeSn alloys with Sn contents of 8.4 % and 10.7 % are grown pseudomorphically on Ge buffers on Si (001) substrates. The alloys as-grown are compressively strained, and therefore indirect bandgap. Undercut GeSn on Ge microdisk structures are fabricated and strained by silicon nitride stressor layers, which leads to tensile strain in the alloys, and direct bandgap photoluminescence in the 3–5 µm gas sensing window of the electromagnetic spectrum. The use of pseudomorphic layers and external stress mitigates the need for plastic deformation to obtain direct bandgap alloys. It is demonstrated, that the optically pumped light emission overlaps with the methane absorption lines, suggesting that GeSn alloys are well suited for mid-infrared integrated gas sensors on Si chips

Germanium/silicon heterostructures for terahertz emission

Progress towards Si/Ge terahertz quantum cascade lasers is reviewed, and the relative merits of different Si/Ge materials configurations for such lasers are compared. The prospects for Gebased quantum cascade lasers are discussed, and supported by simulation work for realistic laser designs. Experimental progress and challenges are assessed

Genome-wide meta-analysis identifies 127 open-angle glaucoma loci with consistent effect across ancestries

10.1038/s41467-020-20851-4Nature Communications121125