diff --git a/main.log b/main.log index f3bff58..5ab164a 100644 --- a/main.log +++ b/main.log @@ -1,4 +1,4 @@ -This is pdfTeX, Version 3.141592653-2.6-1.40.25 (TeX Live 2023 - Flatpak) (preloaded format=pdflatex 2023.4.15) 15 MAY 2023 14:12 +This is pdfTeX, Version 3.141592653-2.6-1.40.25 (TeX Live 2023 - Flatpak) (preloaded format=pdflatex 2023.4.15) 15 MAY 2023 14:22 entering extended mode restricted \write18 enabled. %&-line parsing enabled. @@ -6820,7 +6820,7 @@ LaTeX Font Warning: Some font shapes were not available, defaults substituted. LaTeX Warning: There were multiply-defined labels. Package rerunfilecheck Info: File `main.out' has not changed. -(rerunfilecheck) Checksum: A9BD0E86FECEE4658341A20333AC74FE;10815. +(rerunfilecheck) Checksum: F8AFE30ED53A7D34C858D6E10240DF89;10815. Package logreq Info: Writing requests to 'main.run.xml'. \openout1 = `main.run.xml'. @@ -6870,7 +6870,7 @@ txfonts/rtxmi.pfb> mf-dist/fonts/type1/public/newtx/txsys.pfb> -Output written on main.pdf (170 pages, 18929696 bytes). +Output written on main.pdf (170 pages, 18929664 bytes). PDF statistics: 3889 PDF objects out of 4296 (max. 8388607) 2880 compressed objects within 29 object streams diff --git a/main.out b/main.out index 3067ad3..2d0c503 100755 --- a/main.out +++ b/main.out @@ -26,7 +26,7 @@ \BOOKMARK [1][-]{section.4.5}{\376\377\000S\000c\000a\000t\000t\000e\000r\000i\000n\000g\000\040\000a\000t\000\040\000g\000r\000a\000z\000i\000n\000g\000\040\000i\000n\000c\000i\000d\000e\000n\000c\000e}{chapter.4}% 26 \BOOKMARK [0][-]{chapter.5}{\376\377\000M\000u\000l\000t\000i\000l\000a\000y\000e\000r\000\040\000d\000e\000p\000o\000s\000i\000t\000i\000o\000n\000s}{}% 27 \BOOKMARK [1][-]{section.5.1}{\376\377\000M\000a\000g\000n\000e\000t\000r\000o\000n\000\040\000s\000p\000u\000t\000t\000e\000r\000\040\000d\000e\000p\000o\000s\000i\000t\000i\000o\000n}{chapter.5}% 28 -\BOOKMARK [1][-]{section.5.2}{\376\377\000I\000o\000n\000\040\000A\000s\000s\000i\000s\000t\000a\000n\000c\000e}{chapter.5}% 29 +\BOOKMARK [1][-]{section.5.2}{\376\377\000I\000o\000n\000\040\000a\000s\000s\000i\000s\000t\000a\000n\000c\000e}{chapter.5}% 29 \BOOKMARK [1][-]{section.5.3}{\376\377\0001\0001\000B\0004\000C\000\040\000c\000o\000-\000d\000e\000p\000o\000s\000i\000t\000i\000o\000n}{chapter.5}% 30 \BOOKMARK [1][-]{section.5.4}{\376\377\000G\000r\000o\000w\000i\000n\000g\000\040\000h\000i\000g\000h\000-\000p\000e\000r\000f\000o\000r\000m\000a\000n\000c\000e\000\040\000n\000e\000u\000t\000r\000o\000n\000\040\000m\000u\000l\000t\000i\000l\000a\000y\000e\000r\000s}{chapter.5}% 31 \BOOKMARK [1][-]{section.5.5}{\376\377\000D\000e\000p\000o\000s\000i\000t\000i\000o\000n\000\040\000s\000y\000s\000t\000e\000m\000s\000\040\000u\000s\000e\000d\000\040\000i\000n\000\040\000t\000h\000i\000s\000\040\000w\000o\000r\000k}{chapter.5}% 32 diff --git a/main.pdf b/main.pdf index ff2b3e0..5cf0376 100644 Binary files a/main.pdf and b/main.pdf differ diff --git a/main.synctex.gz b/main.synctex.gz index ec5ab8d..54a2d86 100644 Binary files a/main.synctex.gz and b/main.synctex.gz differ diff --git a/main.toc b/main.toc index 057a009..8612b22 100755 --- a/main.toc +++ b/main.toc @@ -45,7 +45,7 @@ \contentsline {section}{\numberline {4.5}Scattering at grazing incidence}{56}{section.4.5}% \contentsline {chapter}{\chapternumberline {5}Multilayer depositions}{61}{chapter.5}% \contentsline {section}{\numberline {5.1}Magnetron sputter deposition}{61}{section.5.1}% -\contentsline {section}{\numberline {5.2}Ion Assistance}{62}{section.5.2}% +\contentsline {section}{\numberline {5.2}Ion assistance}{62}{section.5.2}% \contentsline {section}{\numberline {5.3}$^{11}$B$_4$C co-deposition}{64}{section.5.3}% \contentsline {section}{\numberline {5.4}Growing high-performance neutron multilayers}{65}{section.5.4}% \contentsline {subsection}{\numberline {5.4.1}Reducing interface width}{65}{subsection.5.4.1}% diff --git a/sections/multilayerdepositions.aux b/sections/multilayerdepositions.aux index b6248cb..5081072 100755 --- a/sections/multilayerdepositions.aux +++ b/sections/multilayerdepositions.aux @@ -10,8 +10,8 @@ \@writefile{lof}{\contentsline {figure}{\numberline {5.1}{\ignorespaces A simplified sketch of magnetron sputtering. Incoming Argon ions collide upon the sputtering target, knocking out target atoms which in their turn form a new layer of the material on the substrate.\relax }}{62}{figure.caption.40}\protected@file@percent } \newlabel{magnetronsputtering}{{\M@TitleReference {5.1}{A simplified sketch of magnetron sputtering. Incoming Argon ions collide upon the sputtering target, knocking out target atoms which in their turn form a new layer of the material on the substrate.\relax }}{62}{A simplified sketch of magnetron sputtering. Incoming Argon ions collide upon the sputtering target, knocking out target atoms which in their turn form a new layer of the material on the substrate.\relax }{figure.caption.40}{}} \newlabel{magnetronsputtering@cref}{{[figure][1][5]5.1}{[1][61][]62}} -\@writefile{toc}{\contentsline {section}{\numberline {5.2}Ion Assistance}{62}{section.5.2}\protected@file@percent } -\newlabel{ion_assistance}{{\M@TitleReference {5.2}{Ion Assistance}}{62}{Ion Assistance}{section.5.2}{}} +\@writefile{toc}{\contentsline {section}{\numberline {5.2}Ion assistance}{62}{section.5.2}\protected@file@percent } +\newlabel{ion_assistance}{{\M@TitleReference {5.2}{Ion assistance}}{62}{Ion assistance}{section.5.2}{}} \newlabel{ion_assistance@cref}{{[section][2][5]5.2}{[1][62][]62}} \@writefile{lof}{\contentsline {figure}{\numberline {5.2}{\ignorespaces a) Film growth without ion assistance. Due to the lower adatom mobility, adatoms stick directly to their landing sites, forming a rough surface. b) Ion-assistance during layer growth increases adatom mobility, making surface migration possible. Note how the ions are not part of deposited layer, instead they recoil in the form of neutral gas atoms \blx@tocontentsinit {0}\cite {thesis_naureen}.\relax }}{63}{figure.caption.41}\protected@file@percent } \newlabel{layergrowth}{{\M@TitleReference {5.2}{a) Film growth without ion assistance. Due to the lower adatom mobility, adatoms stick directly to their landing sites, forming a rough surface. b) Ion-assistance during layer growth increases adatom mobility, making surface migration possible. Note how the ions are not part of deposited layer, instead they recoil in the form of neutral gas atoms \cite {thesis_naureen}.\relax }}{63}{a) Film growth without ion assistance. Due to the lower adatom mobility, adatoms stick directly to their landing sites, forming a rough surface. b) Ion-assistance during layer growth increases adatom mobility, making surface migration possible. Note how the ions are not part of deposited layer, instead they recoil in the form of neutral gas atoms \cite {thesis_naureen}.\relax }{figure.caption.41}{}} diff --git a/sections/multilayerdepositions.tex b/sections/multilayerdepositions.tex index 46eb4f2..a5514b4 100755 --- a/sections/multilayerdepositions.tex +++ b/sections/multilayerdepositions.tex @@ -23,7 +23,7 @@ \section{Magnetron sputter deposition} \end{equation} where q is the charge of the particle, $\vb{E}$ the electric field, $\vb{v}$ the velocity of the particle and $\vb{B}$ the magnetic field. The path that the electrons will follow therefore depends on the magnetic and electric fields, a depiction of a typical magnetic configuration in the used deposition systems is shown in Figure \ref{magnetronsputtering}, where the magnetic field is orientated radially above the target surface. The resulting path will follow a trajectory according to the cross-product $\vb{E} \cross \vb{B}$, which gives rise to a circular trajectory above the target surface. This preferential trajectory for the electrons results that more Argon ions will be ionized in this region, leading to a denser plasma. It is for this reason that a circular erosion zone appears on used targets \cite{sputterprocess}. -\section{Ion Assistance}\label{ion_assistance} +\section{Ion assistance}\label{ion_assistance} In order to grow as smooth and abrupt layers as possible, it is important to consider the energy of the incoming adatoms on the multilayer that is being grown. Limited adatom mobility is known to lead to rough interfaces \cite{rough_morphology}, when incoming adatoms have insufficient energy to migrate from their landing sites, they are statistically likely to be at a position that does not contribute to a smoother surface \cite{ERIKSSON200684}, leading to a rougher interface over time. Furthermore, roughness that is already present at the surface will not be smoothened out, but instead the existing interface profile will be replicated throughout the multilayer. Such growth with low adatom mobility will therefore result in rough surfaces with accumulated roughness \cite{thesis_fredrik} where the total interface width increases over time. In order to grow smooth layers, it is therefore important to have enough adatom mobility to allow for surface migration such that adatoms can move to a local energy minimum with many bonds to surrounding atoms that smoothens the interfaces \cite{ERIKSSON200684}. \\ One technique that can be applied to increase adatom mobility it to make use of the ions that are available in the plasma during film growth \cite{thesis_kenneth}. By applying a negative bias on the substrate, there will be a significant potential drop towards the substrate such that the ions will be accelerated towards the film with an energy proportional to the applied substrate bias voltage. When an ion reaches the medium, it interacts with it resulting into different mechanisms of energy and momentum transfer. Given enough energy, this bombardment of ions on the film surface will lead to surface displacement of the adatoms that are present on the surface. This is further illustrated in Figure \ref{layergrowth}, where the ion assistance allows adatoms on the target to move from their landing sites leading to smoother layers. If the ion energy becomes to large however, it can lead to bulk displacement where the adatoms get knocked into the bulk, leading to intermixing between the interfaces. This gives us a clear energy window, where the energy has to be high enough to allow for surface displacements, but low enough to prevent bulk displacement \cite{ERIKSSON200684}. Ideally, all adatoms should be displaced from their landing site, requiring a relatively high ion flux. A magnetic coil is therefore used in order to increase the ion density near the substrate. The magnetic field allows for secondary electrons near the target to be guided from the magnetron source to the sample, surface further ionizing neutral atoms along the way, which therefore leads to a higher incident flux of ions near the sample substrate. \begin{figure}