Nadezhda Bulgakova at the 2023 CLEO Conference

Nadezhda Bulgakova, Head of the Scientific Laser Application department, has participated in the 2023 CLEO Conference (Laser Science to Photonic Applications) which was held in San Jose, CA, USA on May 7-12, 2023. She is a Member of the Subcommittee “Light-Matter Interactions and Materials Processing” of this prestigious conference (also for 2024 CLEO) whose objectives are to provide a forum for discussions of innovative advances, research, and new technologies in all aspects of laser developments from basic research to industry applications.

Nadezhda Bulgakova also gave the oral talk titled “Selective ultrashort laser annealing of amorphous Ge/Si multilayer stacks” in co-authorship with our HiLASE colleagues Alexander Bulgakov, Yoann Levy, Jiří Beránek, and Martin Zukerstein, together with Vladimir A. Volodin and Yuzhu Cheng from Novosibirsk State University, Russia, Siva S. Nagisetty from Coherent Laser Systems GmbH & Co. KG, Germany, and Alexander A. Popov from Valiev Institute of Physics and Technology, Yaroslavl, Russia. The extended two-page abstract will be published by the OPTICA Publishing Group with indexing in the Web of Science and Scopus.

A number of attempts were made to selectively crystallize germanium in amorphous Ge/Si multilayer (ML) systems. However, usually, laser annealing leads to intermixing of Si and Ge nanolayers and to the formation of their alloy. Recently, we achieved successful selective crystallization of germanium layers in an amorphous Ge/Si ML stack using picosecond 1030-nm laser annealing. In the present study, we have extended the irradiation conditions to a longer wavelength (1500 nm) and shorter pulse duration (70 fs) and compared ps and fs annealing regimes with the aim to find optimal conditions for selective crystallization of Ge layers in Ge/Si ML stacks without crystallization of silicon and intermixing Ge and Si layers. The effect of the substrate on the crystallization efficiency has been studied.