In the quest to enhance the resilience of silicon-based materials against radiation, a team of researchers from the University of Grenoble Alpes and CEA Liten has made a significant stride. Led by Charles Seron, the team has developed a novel approach to create radiation-hardened silicon wafers, a breakthrough that could have profound implications for the energy sector, particularly in nuclear and space applications.
The research, published in the Journal of Physics Materials (known in English as “Journal of Physics: Materials”), focuses on combining different techniques to improve the radiation hardness of crystalline silicon substrates. The team employed gallium (Ga) as the primary dopant to achieve p-type conductivity and introduced lithium (Li) co-doping to mitigate radiation-induced defects. “Lithium is known for its capability to mitigate recombination-active radiation-induced defects,” explains Seron. “However, the Li doping procedure raises important challenges, particularly due to its tendency to accumulate on the surface.”
One of the primary challenges the team faced was the incompatibility of direct Li implantation into bare silicon wafers, which led to Li exo-diffusion and surface accumulation. To overcome this, the researchers investigated various barrier layers, including dielectric barrier layers and n+ phosphorus-diffused regions. While the dielectric layers did not favor Li bulk contamination due to Li accumulation within the dielectrics or at the dielectric/substrate interfaces, the n+ region proved to be an efficient barrier.
The successful implementation of this approach allowed the team to produce 90 µm-thick p-type co-doped Ga–Li wafers with an electrically-active Li concentration of 4.7 × 10^15 cm^−3, a value known to significantly improve radiation hardness. This innovation could pave the way for more robust and reliable silicon-based materials in high-radiation environments, such as nuclear power plants and space missions.
The commercial impacts of this research are substantial. In the energy sector, where radiation hardness is crucial, these enhanced silicon wafers could lead to more efficient and durable solar panels, improved semiconductor devices for nuclear reactors, and more resilient electronic components for space exploration. “This research opens up new possibilities for the development of advanced materials that can withstand extreme radiation conditions,” says Seron. “It’s a significant step forward in our quest to improve the performance and reliability of silicon-based technologies in challenging environments.”
As the world continues to push the boundaries of technology, the need for materials that can withstand harsh conditions becomes increasingly important. This research not only addresses this need but also sets the stage for future developments in the field of radiation-hardened materials. With the potential to revolutionize the energy sector, the work of Seron and his team is a testament to the power of innovative scientific research.