  (Si)GeSn semiconductors are finally coming of age after a long gestation
period. The demonstration of device quality epi-layers and quantum-engineered
heterostructures has meant that tunable all-group IV Si-integrated infrared
photonics is now a real possibility. Notwithstanding the recent exciting
developments in (Si)GeSn materials and devices, this family of semiconductors
is still facing serious limitations that need to be addressed to enable
reliable and scalable applications. The main outstanding challenges include the
difficulty to grow high crystalline quality layers and heterostructures at the
desired Sn content and lattice strain, preserve the material integrity during
growth and throughout device processing steps, and control doping and defect
density. Other challenges are related to the lack of optimized device designs
and predictive theoretical models to evaluate and simulate the fundamental
properties and performance of (Si)GeSn layers and heterostructures. This
Perspective highlights key strategies to circumvent these hurdles and bring
this material system to maturity to create far-reaching new opportunities for
Si-compatible infrared photodetectors, sensors, and emitters for applications
in free-space communication, infrared harvesting, biological and chemical
sensing, and thermal imaging.
