Epitaxial growth and nanosecond laser annealing of GeSn/SiGeSn heterostructures
Published : 10 January 2019
Since 2015, CEA LETI has the capacity of depositing GeSn/SiGeSn heterostructures on 200 mm substrates. We are currently at the state-of-the-art in several of their application domains. In ordre to fabricate electically-pumped lasers able to operate at room temperature and performant Infra-Red photodetectors, we will explore during this PhD thesis the n-type and p-type doping of such layers, be it by ion implantation or in-situ during the epitaxial growth itself.
In order to take full advantage of those doped layers, we will perform recristallisation and electrical activation anneals. With standard annealing techniques, we would be faced with the significant instability of GeSn / SiGeSn stacks (tin precipitation / surface segregation). This is why we will evaluate, during this PhD thesis, the interest of using nanosecond laser anneals and their impact on the structural and electrical properties of those stacks. Those studies, which will be conducted in our brand new SCREEN-LASSE LT3100 tool, will be among the first ever conducted on this type of semiconductors.
We will notably focus on the evolution of cristalline quality, doping level, surface roughness, tin agglomeration / segregation and chemical content with the various process parameters (epitaxy and laser anneals). Such a know-how will be put to good use for the fabrication of innovative optoelectronics devices.