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Oral presentation on preparing and characterising Pu-239 recoil ion sources provided U-235m for laser-spectroscopic study given by L. E. Reed at Actinides Conference 2023, June 5-8, 2023, Colorado School of Mines, Golden, CO, USA.

Oral presentation on preparation and characterization of Pu-239 and Pu-240 recoil ion sources for U-235mstudy given by L.E. Reedat the LISA Conference, May 22-26,2023, Leuven, Belgium.

Funding Information: This work was carried out within the MECHALD project funded by Business Finland and is linked to the Finnish Centers of Excellence in Atomic Layer Deposition (Ref. No. 251220) and Nuclear and Accelerator Based Physics (Ref Nos. 213503 and 251353) of the Academy of Finland. Publisher Copyright: © 2022 Author(s). In microelectromechanical system devices, thin films experience thermal processing at temperatures some cases exceeding the growth or deposition temperature of the film. In the case of the thin film grown by atomic layer deposition (ALD) at relatively low temperatures, post-ALD thermal processing or high device operation temperature might cause performance issues at device level or even device failure. In this work, residual stress and the role of intrinsic stress in ALD Al2O3 films grown from Me3Al and H2O, O3, or O2 (plasma ALD) were studied via post-ALD thermal processing. Thermal expansion coefficient was determined using thermal cycling and the double substrate method. For some samples, post-ALD thermal annealing was done in nitrogen at 300, 450, 700, or 900 °C. Selected samples were also studied for crystallinity, composition, and optical properties. Samples that were thermally annealed at 900 °C had increased residual stress value (1400-1600 MPa) upon formation of denser Al2O3 phase. The thermal expansion coefficient varied somewhat between Al2O3 made using different oxygen precursors. For thermal-Al2O3, intrinsic stress decreased with increasing growth temperature. ALD Al2O3 grown with plasma process had the lowest intrinsic stress. The results show that ALD Al2O3 grown at 200 and 300 °C is suitable for applications, where films are exposed to post-ALD thermal processing even at temperature of 700 °C without a major change in optical properties or residual stress.

Poster presentation given at LISA Summer School, Normandy, France, 29.08.22 – 9.09.22.

Presentation on preparation and characterization of Pu-239 recoil ion sources providing U-235m for laser-spectroscopic study given by L. E. Reed on 17.06.2022 for LISA academic day.

SbOx thin films are deposited by atomic layer deposition (ALD) using SbCl5 and Sb(NMe2)3 as antimony reactants and H2O and H2O2 as oxidizers at low temperatures. SbCl5 can react with both oxidizers, while no deposition is found to occur using Sb(NMe2)3 and H2O. For the first time, the reaction mechanism and dielectric properties of ALD-SbOx thin films are systematically studied, which exhibit a high breakdown field of ≈4 MV cm−1 and high areal capacitance ranging from 150 to 200 nF cm−2, corresponding to a dielectric constant ranging from 10 to 13. The ZnO semiconductor layer is integrated into a SbOx dielectric layer, and thin film transistors (TFTs) are successfully fabricated. A TFT with a SbOx dielectric layer deposited at 200 °C from Sb(NMe2)3 and H2O2 presents excellent performance, such as a field effect mobility (µ) of 12.4 cm2 V−1 s−1, Ion/Ioff ratio of 4 × 108, subthreshold swing of 0.22 V dec−1, and a trapping state (Ntrap) of 1.1 × 1012 eV−1 cm−2. The amorphous structure and high areal capacitance of SbOx boosts the interface between the semiconductor and dielectric layer of TFT devices and provide a strong electric field for electrons to improve the device mobility. peerReviewed

The elongation of spherical Au nanoparticles embedded in SiO2 under swift heavy ion (SHI) irradiation is an extensively studied phenomenon. The use of a TEM grid as a substrate facilitates the identification of the same nanoparticle before and after the irradiation. Since the underdensification of SiO2 inside the ion track plays a key role, the elongation is sensitive to the matrix material properties. Therefore, we studied the elongation process of SHI irradiated Au spherical nanoparticles of various diameters (5–80 nm) embedded either in atomic layer deposition (ALD) or plasma-enhanced chemical vapor deposition (PECVD) SiO2. The results show that a different elongation ratio is achieved depending on the particle initial size, ion fluence, and a different SiO2 deposition method. The embedded nanoparticles in ALD SiO2 elongate roughly 100% more than the nanoparticles embedded in PECVD SiO2 at the biggest applied fluence (5×1014ions/cm2). On the other hand, at fluences lower than 1014ions/cm2, nanoparticles elongate slightly more when they are embedded in PECVD SiO2 peerReviewed