(358d) Controlling Structure and Properties of 2D Group IV (Si, Ge) Nanosheets

Continued scientific and technological advancements in computing and microelectronics have resulted in massive improvements in healthcare, and technological advancement, and global development. However, the energy consumption that is attributed to information and communication technology is a growing concern. Integrated photonic circuits could dramatically reduce the energy cost of computing, while also improving computational speed. However, crystalline Si — the backbone of microelectronics—is a poor platform for integrated photonics due to its indirect bandgap, which makes light-emission a forbidden process. Existing optoelectronic materials are incompatible with our existing complementary metal-oxide-semiconductor infrastructure, which makes it difficult to fabricate integrated photonic circuits with the scalability and precision of Si-based microelectronics.

I will present my group’s recent work in synthesizing nanostructured Si and other Group IV semiconductor nanomaterials, including nanocrystals and nanosheets with precise control over their size and surface chemistry. Using NMR, IR spectroscopy, and atomic pair distribution function analysis to gain insight in their local coordination and long-range order. The optoelectronic properties are sensitive to the structure and interfacial chemistry. Using ultrafast spectroscopy, there is evidence of a “direct-like” optical transition in 2D Si nanosheets, which is corroborated by DFT simulations of the band structure. I will also share recent work related to the thermal stability of 2D silicon nanosheets, demonstrating their structure and photoluminescence are stable to temperatures far beyond what they would experience in real applications. Finally, we will demonstrate the potential of these materials for novel device applications in computing and sensing.

References:

1. Ryan,B.J. et al. (2019) "Silicene, siloxene, or silicane? Revealing the structure and optical properties of silicon nanosheets derived from calcium disilicide." Chemistry of Materials 32(2) 795-804.
2. Ryan, B. J., Roling, L. T., & Panthani, M. G. (2021). Anisotropic Disorder and Thermal Stability of Silicane. ACS Nano, 15(9), 14557-14569.
3. Dorn RW, Ryan BJ, Lamahewage SN, Dodson MV, Essner JB, Biswas R, Panthani MG, Rossini AJ. Chlorination of Hydrogenated Silicon Nanosheets Revealed by Solid-State Nuclear Magnetic Resonance Spectroscopy. (2023) Chemistry of Materials. 35, 2, 539–548
4. Livache, C., Ryan, B.J., Ramesh, U., Steinmetz, V., Gréboval, C., Chu, A., Brule, T., Ithurria, S., Prévot, G., Barisien, T. and Ouerghi, A., Panthani, M.G.; Lhuillier, E. (2019). Optoelectronic properties of methyl-terminated germanane. Applied Physics Letters, 115(5), p.052106.