Nanoscale Strain Characterization in Erbium-doped Silicon

• Applicants: Dr. Kevin-Peter Gradwohl; Professor Dr. Andreas Reiserer
• Subject Area: Experimental Condensed Matter Physics
• Term: since 2025
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 569053293

Characterizing the strain in nanoscale silicon devices is of high relevance in the context of both classical and quantum information processing. Strain can be seen alternatively as a source of inhomogeneity to be overcome, or as a vector for interaction between quantum systems. Established characterization approaches based on X-ray scattering, however, do not achieve the required nanoscale spatial resolution. This limitation will be overcome in the NaSCEr project by measuring the strain-induced frequency shift of erbium emitters implanted into silicon nanostructures. To this end, the objectives of the project are: 1) The generation of silicon layers with controlled strain and minimal inhomogeneity by growing isotopically purified 28Si and 28Si76Ge-heterostructures. 2) The quantification of the strain-induced level shifts of individual erbium emitters in silicon nanostructures by high-resolution spectroscopy. 3) The understanding of strain induced by the erbium optical excitation in silicon. 4) The characterization of strain relaxation in nanoscale photonic crystal devices. The proposal contains a challenging set of nanofabrication activities and measurements that only becomes feasible by combining the expertise of the consortium, which includes the growth of isotopically pure Si thin films (K. Gradwohl), erbium integration in Si nanostructures (A. Reiserer), and strain characterization and modeling of emitters in crystals (T. Chanelière). Successful implementation would significantly improve the understanding of the Er:Si system, which is a promising new platform for quantum information processing. In addition, it would enable new insights into strain relaxation in nano-scale devices ranging from ultra-scaled transistors to quantum-dot devices. Finally, it would enable the realization of spin-coupled nanomechanical systems based on Er:Si, and thus pave the way for the long-sought goal of nonlinear optomechanics.

• DFG Programme: Research Grants
• International Connection: France
• Cooperation Partner: Dr. Thierry Chanelière