Si photonics is widely believed to be one of the candidate solutions for extending the Moore's law. The light sources which can be integrated on Si have become the major bottleneck after the successful demonstrations of other components. Group IV semiconductors are more compatible with Si in sense of monolithic integration and current CMOS technology. By introducing tensile strain or incorporate Sn into Ge can convert it into a direct band-gap semiconductor and increase the carrier mobility dramatically simultaneously. The excellent electronic and optical properties of the tensile-strained Ge and GeSn alloy make them the promising materials to construct light sources on Si. Jülich is leading the research on GeSn material and devices based on the chemical vapor deposition (CVD) technology in the world and has demonstrated the first GeSn laser (Nat Phot. 9, 88 (2015)). The research on GeSn in SIMIT is based on molecular beam epitaxy (MBE) technology and focuses on nano- and micro- structures. The collaboration on group IV light emitting materials and devices combines the advantages of different material growth technologies and explores devices in different dimensions.

The collaboration on group IV materials has started in 2017. Material exchange has been implemented. GeSn thin films with different Sn concentrations grown by CVD have been sent from Jülich to SIMIT. They will be characterized and then compared with the MBE grown materials, and fabricated into suspended light-emitting micro-devices.