0000000000017640
AUTHOR
Jari Koskinen
showing 5 related works from this author
Characterization and Electrochemical Properties of Oxygenated Amorphous Carbon (a-C) Films
2016
Amorphous carbon (a-C) films with varying oxygen content were deposited by closed-field unbalanced magnetron sputtering with the aim to understand the effect of oxygen on the structural and physical properties of the films and subsequently correlate these changes with electrochemical properties. The a-C films were characterized by transmission electron microscopy, helium-ion microscopy, atomic force microscopy, Raman spectroscopy, X-ray photoelectron spectroscopy and time-of-flight elastic recoil detection analysis. The electrochemical properties were studied by electrochemical impedance spectroscopy and cyclic voltammetry with several redox systems (Ru(NH3)62+/3+, Fe(CN)64−/3−, dopamine an…
Room-Temperature Micropillar Growth of Lithium-Titanate-Carbon Composite Structures by Self-Biased Direct Current Magnetron Sputtering for Lithium Io…
2019
Here, an unidentified type of micropillar growth is described at room temperature during conventional direct-current magnetron sputtering (DC-MS) deposition from a Li4Ti5O12+graphite sputter target under negative substrate bias and high operating pressure. These fabricated carbon-Li2O-TiO2 microstructures consisting of various Li4Ti5O12/Li2TiO3/LixTiO2 crystalline phases are demonstrated as an anode material in Li-ion microbatteries. The described micropillar fabrication method is a low-cost, substrate independent, single-step, room-temperature vacuum process utilizing a mature industrial complementary metal-oxide-semiconductor (CMOS)-compatible technology. Furthermore, tentative considerat…
Nanotribological, nanomechanical and interfacial characterization of atomic layer deposited TiO2 on a silicon substrate
2015
Abstract For every coating it is critical that the coatings are sufficiently durable to withstand practical applications and that the films adhere well enough to the substrate. In this paper the nanotribological, nanomechanical and interfacial properties of 15–100 nm thick atomic layer deposited (ALD) TiO 2 coatings deposited at 110–300 °C were studied using a novel combination of nanoscratch and scanning nanowear testing. Thin film wear increased linearly with increasing scanning nanowear load. The film deposited at 300 °C was up to 58±11 %-points more wear-resistant compared to the films deposited at lower temperatures due to higher hardness and crystallinity of the film. Amorphous/nanocr…
What Determines the Electrochemical Properties of Nitrogenated Amorphous Carbon Thin Films?
2021
Funding Information: We acknowledge the provision of facilities by RawMatters Finland Infrastructure (RAMI, no. 292884), Aalto University Bioeconomy, and OtaNano - Nanomicroscopy Center (Aalto-NMC). Use of the Stanford Synchrotron Radiation Lightsource, SLAC National Accelerator Laboratory, is supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences under contract no. DE-AC02-76SF00515. We acknowledge CSC – IT Center for Science, Finland, for computational resources. S.S. acknowledges funding from the Walter Ahlström Foundation. This project has received funding from the European Union’s Horizon 2020 research and innovation programme under the Marie Skł…
Aluminum oxide from trimethylaluminum and water by atomic layer deposition:The temperature dependence of residual stress, elastic modulus, hardness a…
2014
Use of atomic layer deposition (ALD) in microelectromechanical systems (MEMS) has increased as ALD enables conformal growth on 3-dimensional structures at relatively low temperatures. For MEMS device design and fabrication, the understanding of stress and mechanical properties such as elastic modulus, hardness and adhesion of thin film is crucial. In this work a comprehensive characterization of the stress, elastic modulus, hardness and adhesion of ALD aluminum oxide (Al2O3) films grown at 110-300 C from trimethylaluminum and water is presented. Film stress was analyzed by wafer curvature measurements, elastic modulus by nanoindentation and surface-acoustic wave measurements, hardness by na…