Microstructure and morphology of thin films are decisive for many of their resulting properties. To be able to tailor these properties, and thus the film functionality, a fundamental understanding of thin film growth needs to be acquired. Film growth is commonly performed using continuous vapor fluxes with low energy, but additional handles to control growth can be obtained by instead using pulsed and energetic ion fluxes. In this licentiate thesis the physical processes that determine microstructure and morphology of thin films grown using pulsed and highly ionized vapor fluxes are investigated.

The underlying physics that determines the initial film growth stages (i.e., island nucleation, island growth and island coalescence) and how they can be manipulated individually when using pulsed vapor fluxes have previously been investigated. Their combined effect on film growth is, however, paramount to tailor film properties. In the thesis, a route to generate pulsed vapor fluxes using the vapor-based technique high power impulse magnetron sputtering (HiPIMS) is established. These fluxes are then used to grow Ag films on SiO₂ substrates. For fluxes with constant energy and deposition rate per pulse it is demonstrated that the growth evolution is solely determined by the characteristics of the vapor flux, as set by the pulsing frequency, and the average time required for coalescence to be completed.

Highly ionized vapor fluxes have previously been used to manipulate film growth when deposition is performed both normal and off-normal to the substrate. For the latter case, the physical mechanisms that determine film microstructure and morphology are, however, not fully understood. Here it is shown that the tilted columnar microstructure obtained during  off-normal film growth is positioned closer to the substrate normal as the ionization degree of the flux increases, but only if certain nucleation characteristics are present.

Thin film growth from the vapor phase has for a long time intrigued researchers endeavouring to unravel and understand atomistic surface processes that govern film formation. Their motivation has not been purely scientific, but also driven by numerous applications where this understanding is paramount to knowledge-based design of novel film materials with tailored properties.

Within the above framework, this thesis investigates growth of metal films on weakly bonding substrates, a combination of great relevance for applications concerning e.g., catalysis, graphene metallization and architectural glazing. When metal vapor condenses on weakly bonding substrates three dimensional islands nucleate, grow and coalesce prior to forming a continuous film. The combined effect of these initial growth stages on film formation and morphology evolution is studied using pulsed vapor fluxes for the model system Ag/SiO2. It is shown that the competition between island growth and coalescence completion determines structure evolution. The effect of the initial growth stages on film formation is also examined for the tilted columnar microstructure obtained when vapor arrives at an angle that deviates from the substrate surface normal. This is done using two metals with distinctly different nucleation behaviour, and the findings suggest that the column tilt angle is set by nucleation conditions in conjunction with shadowing of the vapor flux by adjacent islands. Vapor arriving at an angle can in addition result in films that exhibit preferred crystallographic orientations, both out-of-plane and in-plane. Their emergence is commonly described by an evolutionary growth model, which for some materials predict a double in-plane alignment that has not been observed experimentally. Here, an experiment is designed to replicate the model’s growth conditions, confirming the existence of double in-plane alignment.

New and added film functionalities can further be unlocked by alloying. Properties are then largely set by chemistry and atomic arrangement, where the latter can be affected by thermodynamics, kinetics and vapor flux modulation. Their combined effect on atomic arrangement is here unravelled by presenting a research methodology that encompasses high resolution vapor flux modulation, nanoscale structure v vi probes and growth simulations. The methodology is deployed to study the immiscible Ag-Cu and miscible Ag-Au model systems, for which it is shown that capping of Cu by Ag atoms via near surface diffusion processes and rough morphology of the Ag-Au growth front are the decisive structure forming processes in each respective system.

The results generated in this thesis are of relevance for tuning structure of metal films grown on weakly bonding substrates. They also indicate that improved growth models are required to accurately describe structure evolution and emergence of a preferred in-plane orientation in films where vapor arrives at an angle that deviates from the substrate surface normal. In addition, this thesis presents a methodology that can be used to identify and understand structure forming processes in multicomponent films, which may enable tailoring of atomic arrangement and related properties in technologically relevant material systems.