Cold atmospheric plasmas for material synthesis: generation of silicon quantum dots and particle-free thin film deposition

• Applicant: Professor Jan Benedikt, Ph.D., since 2/2022
• Subject Area: Optics, Quantum Optics and Physics of Atoms, Molecules and Plasmas
• Term: from 2020 to 2023
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 426208229

The goal of this research project is to characterize and understand plasma-chemical processes leading to the formation of nanoparticles and thin films in cold (non-equilibrium) atmospheric plasmas (CAPs) or in plasma-initiated photochemistry and to use the gained knowledge to generate good quality ultra-small (<4 nm) nanoparticles and thin films. These goals will be achieved by an investigation of selected model particle generation and thin film deposition processes analyzed by the combination of the state-of-the-art in situ diagnostics in two parallel projects performed by two Ph.D. candidates.The first Ph.D. will investigate the generation of optical quality Si-NCs with controllable size and surface passivation. Generation of Si-NCs will serve as a model process, where the crystal size and surface passivation strongly influence their optical and electrical properties. The growth of ultra-small (< 4 nm) single crystal Si-NCs will be specifically aimed in a flexible dual-plasma system with separated NC generation and treatment. A state-of-the-art 1 nm scanning mobility particle sizer (1 nm SMPS) is available for the analysis, where the detection limit close to 1 nm diameter closes the gap between common quadrupole mass spectrometry and SMPS. The optical properties of the generated Si-NCs will be studied with a collaboration partner at the Czech Academy of Sciences.The second Ph.D. will study plasma-chemical processes in the CAP-based deposition of particle-free thin films from HMDSO/O2, C2H2 or SiH4 gases including the first experiments on the thin film deposition from vacuum-UV initiated photochemistry process, a novel deposition method proposed in the project with CAP as a source of the vacuum-UV photons. The state-of-the-art threshold ionization molecular beam mass spectrometry (MBMS) will be combined with the 1 nm SMPS and Fourier Transform InfraRed spectroscopy (FTIR) as diagnostic methods.Both Ph.D. candidates will mutually profit from the possibility to use the advanced diagnostic method(s) of the parallel project and their gained expertise in the fields of particle formation and plasma-chemistry investigations. The outcomes of this project will be i) the better understanding of the nanoparticle formation and thin film deposition by means of CAPs and ii) improved (double plasma system for generation of ultra-small NCs) or new (vacuum-UV initiated photochemistry) material synthesis methods.

• DFG Programme: Research Grants
• International Connection: Czech Republic
• Cooperation Partner: Dr. Katerina Herynková
• Ehemaliger Antragsteller: Sadegh Askari, Ph.D., until 1/2022