Unravelling the ion-energy-dependent structure evolution and its implications for the elastic properties of (V,Al)N thin films

Acta Materialia, vol. 214, pp. 117003

Abstract

Ion irradiation-induced changes in the structure and mechanical properties of metastable cubic (V,Al)N deposited by reactive high power pulsed magnetron sputtering are systematically investigated by correlating experiments and theory in the ion kinetic energy (Ek) range from 4 to 154 eV. Increasing Ek results in film densification and the evolution from a columnar (111) oriented structure at Ek ≤ 24 eV to a fine-grained structure with (100) preferred orientation for Ek ≥ 104 eV. Furthermore, the compressive intrinsic stress increases by 336 % to -4.8 GPa as Ek is increased from 4 to 104 eV. Higher ion kinetic energy causes stress relaxation to -2.7 GPa at 154 eV. These ion irradiation-induced changes in the thin film stress state are in good agreement with density functional theory simulations. Furthermore, the measured elastic moduli of (V,Al)N thin films exhibit no significant dependence on Ek. The apparent independence of the elastic modulus on Ek can be rationalized by considering the concurrent and balancing effects of bombardment-induced formation of Frenkel pairs (causing a decrease in elastic modulus) and evolution of compressive intrinsic stress (causing an increase in elastic modulus). Hence, the evolution of the film stresses and mechanical properties can be understood based on the complex interplay of ion irradiation-induced defect generation and annihilation.

Authors 9

1. Soheil Karimi Aghda corresponding Aachen Materials Chemistry

   RWTH Aachen University

   Affiliation as printed

   Materials Chemistry, RWTH Aachen University, Kopernikusstr. 10, 52074 Aachen, Germany

2. Denis Mušić

   Malmö University

   Affiliation as printed

   Department of Materials Science and Applied Mathematics, Malmö University, 20506 Malmö, Sweden

3. Yeliz Unutulmazsoy

   Leibniz Institute of Surface Engineering

   Affiliation as printed

   Leibniz Institute of Surface Engineering (IOM), Permoserstr. 15, 04318 Leipzig, Germany

4. Heng Han Sua Aachen Materials Chemistry

   RWTH Aachen University

   Affiliation as printed

   Materials Chemistry, RWTH Aachen University, Kopernikusstr. 10, 52074 Aachen, Germany

5. Stanislav Mráz Aachen Materials Chemistry

   RWTH Aachen University

   Affiliation as printed

   Materials Chemistry, RWTH Aachen University, Kopernikusstr. 10, 52074 Aachen, Germany

6. Marcus Hans Aachen Materials Chemistry

   RWTH Aachen University

   Affiliation as printed

   Materials Chemistry, RWTH Aachen University, Kopernikusstr. 10, 52074 Aachen, Germany

7. Daniel Primetzhofer

   Uppsala University

   Affiliation as printed

   Department of Physics and Astronomy, Uppsala University, Lägerhyddsvägen 1, 75120 Uppsala, Sweden

8. André Anders

   Leibniz Institute of Surface Engineering · Leipzig University

   Affiliation as printed

   Felix Bloch Institute, Leipzig University, Linnéstr. 5, 04103 Leipzig, Germany

   Leibniz Institute of Surface Engineering (IOM), Permoserstr. 15, 04318 Leipzig, Germany

9. Jochen M. Schneider Aachen Materials Chemistry

   RWTH Aachen University

   Affiliation as printed

   Materials Chemistry, RWTH Aachen University, Kopernikusstr. 10, 52074 Aachen, Germany