Innovative Annealing Technology for Thermally Stable Ni(GeSn) Alloys

GeSn alloys are very promising materials for Si-based photonics and CMOS technologies. Performant contacts are definitely needed to make the most of innovative Mid Infra-Red (MIR) GeSn-based devices such as Light Emitting Devices, electrically pumped lasers, photo-detectors and so on. The most reported metallization scheme on GeSn is based on Ni. Ni has indeed the advantage of forming a Ni(GeSn) alloy at relatively low temperature that exhibits low resistivity and contact resistance. On the other hand, the main drawback of the Ni(GeSn) alloy is its poor thermal stability because of 2 phenomena: Ni(GeSn) agglomeration and Sn segregation. Technological alternatives have thus been evaluated to enhance the thermal stability of the Ni / GeSn system. As for instance, the use of pre-amorphization by implantation (PAI) prior to metallization and the addition of alloying elements, such as Pt and Co, have been reported in Ni-based metallization [1–3].