2023 R.F. Bunshah Award & ICMCTF Lecture Recipient

Purpose

R.F. Bunshah Award and Honorary ICMCTF lectureship is intended to recognize outstanding research or technological innovation in the areas of interest to the Advanced Surface Engineering Division (ASED) of the AVS, with emphasis in the fields of surface engineering, thin films, and related topics.

Biography

Lars Hultman received a Ph.D. degree in 1988 and became professor/Head of Thin Film Physics at IFM, Linköping University (Sweden) in 1999. Since 2013 he has been Chief Executive Officer of the Swedish Foundation for Strategic Research with time for research. Lars has 900 publications and over 100 invited international conference presentations and plenaries. He made sabbaticals to Northwestern University and the University of Illinois at Urbana-Champaign. He is an elected member of the Royal Swedish Academies of Science (KVA) and Engineering Sciences (IVA), as well as Fellow of the American Vacuum Society. In 2021 he was announced Court Chamberlain to His Majesty the King Carl XVI Gustaf. Other recognitions include the European ERC Advanced Grant, Wallenberg Scholar, AkzoNobel Science Award, and editor-in-chief of VACUUM. He served as General Chair and Program Chair for the International Conference of Thin Films & Metallurgical Coatings. He founded and directed a series of research centers of excellence. His application-inspired basic research has yielded 20 patents on coated cutting tools, neutron-detector films, and ultra-low friction coatings for bearings. He has supervised 40+ graduate students to Ph.D., 20+ post-doc fellows, and mentored generations of research leaders at various universities.

Abstract

“What TEM, XRD, STM, AFM, HIM, LEED, 3DATP, DSC, Nanoindentation, DFT, and MD Tell You About Functional Nanostructured Ceramics“

Wednesday, May 24, 2023 – 5:45 PM (PT)
Room: Town & Country A

This presentation reviews strategies for characterizing diverse nanostructures that form in functional nitride thin films during vapor deposition intended to enhance mechanical and electronic properties. Material design is obtained by self-organization during surface- and bulk-driven segregations and phase transformation in metastable TiAlN, ZrAlN, HfAlN, TiSiN, MoVN, VWN, and InAlN alloy model systems, and analyzed by a suite of materials science tools. Density functional theory (DFT) calculations are employed to assess phase stability and decomposition from lattice mismatch and electronic band structure effects. The concept of age hardening is discussed for isostructural systems whereby spinodal decomposition is established for TiAlN by the formation of cubic-phase nm-size domains in a checker-board-pattern of TiN and AlN during annealing, as studied by XRD, TEM, atom probe tomography (APT) and differential scanning caloriometry (DSC). 2-D-nanolabyrinthine structuring in ZrAlN is obtained from the intergrowth of non-isostructural phases c-ZrN/w-AlN: {110}║{11-20} interfaces. Focused-ion beam (FIB) is used to prepare cross-sectional TEM samples of TiN-based films with nanoindents to study plastic deformation from dislocation slip. Superhardening in TiN/Si₃N₄nanocomposites takes place due to Si segregation forming a few-monolayer-thick SiN_x tissue phase, which is a vacancy-stabilized cubic-SiN_x layer, as shown by STM, LEED, and annular-bright-field STEM.Si segregation is demonstrated in APT using ¹⁵N isotopic substitution to resolve mass spectral overlap between Si and N. DFT is combined with molecular dynamics (MD) simulations to study growth of TiN with a competition for preferred crystallographic orientation (001) vs (111). High fluxes of low-energy (~20 eV) nitrogen ions control atomic layer roughening and yield low-temperature sputter epitaxy, as adatoms diffusing on an upper terrace require an additional energy (the Ehrlich barrier) to cross descending step edges. The barrier asymmetry at step edges leads to up-hill flux resulting in kinetic roughening. Step-flow growthof ductile inherently nanolaminated MAX phases likeTi₃AlC₂is confirmed by atom force microscopy (AFM) and helium ion microscopy (HIM). Scanning TEM/EDX elemental mapping reveals a new growth phenomenon – transmorphic heteroepitaxy – which takes place between CVD-grown AlN epilayer and SiC(0001) wafer substrates. The atomic chemical configuration transits over two atomic layers from SiC to AlN. The resulting AlN layer enables growth of high-quality thin GaN HEMT heterostructures. Finally, curved-lattice epitaxial growth of In_xAl_1-xN core-shell nanospirals is presented.