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Master Thesis on the Investigation of stress in PVD-grown AlN as a thermal barrier layer in nano-multilayered coatings
In this master thesis, we propose a systematic investigation of the stress curvature in AlN barrier layers opportunely prepared by PVD sputtering at different conditions. The obtained AlN microstructures will be related to stress state and applied in Ag/AlN multilayers.
Multilayered architectures, which comprise a periodic alternation of different single- or multiple-elemental layers, are a versatile and promising route to tailor the properties and/or durability of functional materials in various application areas, such as those related to optical, magnetic, and electronic devices, tribology, nano-joining and mechanical engineering. The combination of nano-confinement and interfacial effects between a metal filler and a barrier layer in such nano-multilayered (NML) systems may be exploited to optimize specific material properties, such as mechanical strength, reflectivity, pre-melting or superheating behaviour and electrical conductivity. However, NML architectures are intrinsically thermodynamically unstable and typically exhib-it large residual stresses, which may deteriorate their long-term stability under harsh operation conditions (e.g., elevated temperatures, complex loading conditions) [1,2,3]. In particular, the role of barrier layer is highly important in determining the final stability and performance of the NML. Thermal degradation and metal filler surface outflow can be tailored by tuning the internal stress, the individual layer thickness and the micro-structure of the barrier layer. In this master thesis, we propose a systematic investigation of the AlN barrier layer opportunely prepared by magnetron sputtering. In-situ stress monitor will allow to measure the stress during the growth at various deposition conditions. Different AlN microstructures and internal stress states will be obtained by changing the deposition conditions during the growth and properly characterized by XRD and SEM as main techniques. The effect of the AlN morphology, microstructure and internal stress will be then applied to the Ag/AlN multilayers where thermal stability during post-annealing will be studied and related to the tuned AlN barrier microstructures.
[1] M. Chiodi et al., J. Mater. Chem. C 4, 4927 (2016).
[2] F. Moszner et al., Acta Materialia 107, 345-353 (2016).
[3] V. Araullo-Peters et al., ACS Appl.Mater. Interfaces 11, 6605-6614 (2019).
Multilayered architectures, which comprise a periodic alternation of different single- or multiple-elemental layers, are a versatile and promising route to tailor the properties and/or durability of functional materials in various application areas, such as those related to optical, magnetic, and electronic devices, tribology, nano-joining and mechanical engineering. The combination of nano-confinement and interfacial effects between a metal filler and a barrier layer in such nano-multilayered (NML) systems may be exploited to optimize specific material properties, such as mechanical strength, reflectivity, pre-melting or superheating behaviour and electrical conductivity. However, NML architectures are intrinsically thermodynamically unstable and typically exhib-it large residual stresses, which may deteriorate their long-term stability under harsh operation conditions (e.g., elevated temperatures, complex loading conditions) [1,2,3]. In particular, the role of barrier layer is highly important in determining the final stability and performance of the NML. Thermal degradation and metal filler surface outflow can be tailored by tuning the internal stress, the individual layer thickness and the micro-structure of the barrier layer. In this master thesis, we propose a systematic investigation of the AlN barrier layer opportunely prepared by magnetron sputtering. In-situ stress monitor will allow to measure the stress during the growth at various deposition conditions. Different AlN microstructures and internal stress states will be obtained by changing the deposition conditions during the growth and properly characterized by XRD and SEM as main techniques. The effect of the AlN morphology, microstructure and internal stress will be then applied to the Ag/AlN multilayers where thermal stability during post-annealing will be studied and related to the tuned AlN barrier microstructures.
[1] M. Chiodi et al., J. Mater. Chem. C 4, 4927 (2016). [2] F. Moszner et al., Acta Materialia 107, 345-353 (2016). [3] V. Araullo-Peters et al., ACS Appl.Mater. Interfaces 11, 6605-6614 (2019).
The goal of the thesis is to systematically investigate the internal stress and microstructure of AlN layers produced in different growth conditions. The thesis involves: (a) aspects of PVD process technologies, (b) stress monitoring by measuring wafer curvature during the growth, (c) extensive structural analysis by XRD, (c) detailed characterization of surface properties by SEM, (d) use of high temperature furnaces. Duration: 6 months (master thesis). We are looking for motivated students in the field of Chemistry/Materials Science/Physics/Electrical Engineering willing to work in a multi-disciplinary team to carry out systematic experiments for material analysis.
The goal of the thesis is to systematically investigate the internal stress and microstructure of AlN layers produced in different growth conditions. The thesis involves: (a) aspects of PVD process technologies, (b) stress monitoring by measuring wafer curvature during the growth, (c) extensive structural analysis by XRD, (c) detailed characterization of surface properties by SEM, (d) use of high temperature furnaces. Duration: 6 months (master thesis). We are looking for motivated students in the field of Chemistry/Materials Science/Physics/Electrical Engineering willing to work in a multi-disciplinary team to carry out systematic experiments for material analysis.
If you are interested or want to learn more, please contact Dr C.Cancellieri(claudia.cancellieri@empa.ch).
If you are interested or want to learn more, please contact Dr C.Cancellieri(claudia.cancellieri@empa.ch).