Thin films, or thin layers of materials, are all around us, from the photochromic coating on windows to the hard coating on drills. All electronic devices are constructed from stacks of thin films with carefully controlled properties. Much of the work in the Pedersen group is centred around chemical vapour deposition (CVD), a process for deposing thin film by chemical reaction s between molecules and surfaces. Our aim is to develop better CVD routes to deposit materials for applications ranging from hard coatings on cutting tools, to neutron converter layers for neutron detectors, to electrically conducting, insulating, and semiconducting layers for electronic chip fabrication. We are also exploring “reversed CVD”, i.e., etching of materials by surface chemical reactions.
Plasma discharge above the substrate holder in one of our CVD reactors.
Surface chemistry is central
Cross section electron micrograph of a silicon carbide film where the crystal orientation was altered during the CVD growth by using aliphatic or aromatic hydrocarbons in alternating cycles. From Huang et al. Surf. Coat. Technol. 2022, 447, 128853. Fully controlled and fully understood surface chemistry is at the centre of our research. To this goal we explore various time-resolved CVD approaches, e.g., atomic layer deposition (ALD), surface passivating molecules, and reaction kinetics control to enhance deposition into deep features. We are pioneering surface chemical reactions with free electrons from plasmas, accessing new ways to deposit and etch materials.
Sustainable production
Perfectly conformal, amorphous B5C film deposited on a 8:1 aspect ratio silicon structure by controlling the deposition kinetics in a continuous CVD process. From Choolakkal et al. J. Vac. Sci. Technol. A 2023, 41, 013401. We are also studying how CVD processesCross section electron micrograph of a silicon carbide film where the crystal orientation was altered during the CVD growth by using aliphatic or aromatic hydrocarbons in alternating cycles. From Huang et al. Surf. Coat. Technol. 2022, 447, 128853.can be more sustainable by better design of CVD reactors and CVD chemistry, and by developing life cycle assessment (LCA) methods for CVD processes. The aim of our work is easier and better processes to manipulate materials at the atomic scale for e.g., a better and more sustainable fabrication of chips. Such processes have relevance for several of the UN sustainability goals, e.g., Clean Energy (goal 7), and Industrial Innovation (goal 9).
We collaborate closely with computational groups for studies of CVD gas phase- and surface chemistry, and with materials science- and plasma physics groups, as well as with several companies. If you want to do a bachelor- och master thesis with us, or collaborate in some way, please contact Henrik Pedersen.
Adsorption of trimethyl aluminium onto an amino terminated AlN (0001) surface showing (a) the potential energy surface for adsorption and (b) the molecular structure for adsorption at an energy minimum, forming a Lewis adduct, and (c) transition state structure for diffusing between two Lewis adduct sites. From Rönnby et al. J. Mater. Chem. C 2023, 11, 13935.
