proof read part 1, added design drawing
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coursework.lyx
175
coursework.lyx
@ -140,7 +140,7 @@ f=\frac{c}{\lambda}
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\end_layout
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\begin_layout Standard
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In order to find the
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Therefore in order to find the
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\begin_inset Formula $E$
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\end_inset
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@ -172,14 +172,15 @@ Returning to the specifications, this allows 1.55μm to be expressed as 1.28x10
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\end_layout
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\begin_layout Standard
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This energy value will be the same as the total band gap for the well from
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the first hole energy level to the first electron enery level, shown as
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This energy value will be the same as the total interband transition for
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the well from the first confined hole energy level to the first confined
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electron enery level,
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\end_layout
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\begin_layout Standard
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\begin_inset Formula
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\begin{equation}
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\varSigma E_{g}=E_{1h}+E_{g}+E_{1e}\thickapprox0.8eV\label{eq:Energy-Gap-Sum}
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E_{g,transition}=E_{1h}+E_{g}+E_{1e}\thickapprox0.8\unit{eV}\label{eq:Energy-Gap-Sum}
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\end{equation}
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\end_inset
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@ -221,7 +222,7 @@ status open
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\begin_layout Plain Layout
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Band structure of an AlGaAs/GaAs/AlGaAs quantum well including discrete
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energy levels
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confined energy levels
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\begin_inset CommandInset citation
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LatexCommand cite
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key "ieee_s6824198"
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@ -253,18 +254,18 @@ name "fig:Well-Band-structure"
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\begin_inset Formula $E_{g}$
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\end_inset
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should be the dominant term in this equation and as such in investigating
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suitable materials, the bulk band gap should be close to but lower than
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should be the dominant term in this equation and as such when investigating
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suitable materials the bulk band gap should be close to but lower than
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0.8eV.
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\end_layout
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\begin_layout Standard
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None of the binary III-V indium based alloys have bulk band gaps in a suitable
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range, as such ternary alloys were investigated.
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Ternary alloys were investigated in order to allow precise control over
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the lattice constants and band gap by varying the composition ratio.
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\end_layout
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\begin_layout Standard
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indium gallium arsenide (In
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Indium gallium arsenide (In
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\begin_inset script subscript
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\begin_layout Plain Layout
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@ -327,7 +328,7 @@ Lattice matching is the process of ensuring that two crystalline structures
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between the two materials.
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This is particularly important for quantum wells formed through epitaxial
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growth as strain introduced between such thin layers can cause defects
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ultimately negatively affecting it's electronic properties.
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which ultimately negatively affect it's electronic properties.
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\end_layout
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\begin_layout Standard
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@ -487,7 +488,7 @@ name "tab:Lattice-constants"
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In order to compute a compound lattice constant for InGaAs, Vegard's law
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can be applied.
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Vegard's law provides an approximation for the lattice constant of a solid
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solution by finding the weighted average the individual lattice constants
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solution by finding the weighted average of the individual lattice constants
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by composition ratio and is given by:
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\end_layout
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@ -742,8 +743,8 @@ Width Calculation
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\begin_layout Standard
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Having found two materials that are lattice matched with a suitable band
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gap value, the final calculation is that of the quantum well width.
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In order to calculate this value, the equation for energy levels within
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an infinite quantum well will be used,
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In order to calculate this value, the equation for confined energy levels
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within an infinite quantum well will be used,
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\end_layout
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\begin_layout Standard
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@ -787,7 +788,7 @@ noprefix "false"
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\begin_layout Standard
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\begin_inset Formula
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\[
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\varSigma E_{g}=0.8\unit{eV}=E_{1h}+E_{g}+E_{1e}=\frac{1^{2}\pi^{2}\text{\emph{ħ}}^{2}}{2m_{h}^{*}L^{2}}+E_{g}+\frac{1^{2}\pi^{2}\text{\emph{ħ}}^{2}}{2m_{e}^{*}L^{2}}
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E_{g,transition}=0.8\unit{eV}=E_{1h}+E_{g,InGaAs}+E_{1e}=\frac{1^{2}\pi^{2}\text{\emph{ħ}}^{2}}{2m_{h}^{*}L^{2}}+E_{g,InGaAs}+\frac{1^{2}\pi^{2}\text{\emph{ħ}}^{2}}{2m_{e}^{*}L^{2}}
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\]
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\end_inset
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@ -797,16 +798,16 @@ noprefix "false"
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\begin_layout Standard
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With the experimentally determined value for
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\begin_inset Formula $E_{g}$
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\begin_inset Formula $E_{g,,InGaAs}$
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\end_inset
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this equation can be condensed to,
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this equation becomes
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\end_layout
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\begin_layout Standard
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\begin_inset Formula
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\[
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0.8\unit{eV}=\frac{\pi^{2}\text{\emph{ħ}}^{2}}{2m_{h}^{*}L^{2}}+0.75+\frac{\pi^{2}\text{\emph{ħ}}^{2}}{2m_{e}^{*}L^{2}}
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0.8\unit{eV}=\frac{\pi^{2}\text{\emph{ħ}}^{2}}{2m_{h}^{*}L^{2}}+0.75\unit{eV}+\frac{\pi^{2}\text{\emph{ħ}}^{2}}{2m_{e}^{*}L^{2}}
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\]
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\end_inset
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@ -1064,7 +1065,7 @@ which reduces to a well length of 14.87nm.
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\end_layout
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\begin_layout Subsection
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Energy Level Calculations
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Confined Energy Level Calculations
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\end_layout
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\begin_layout Standard
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@ -1113,8 +1114,8 @@ E_{1e}=6.65\times10^{-21}\unit{J}=0.041\unit{eV}
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\end_layout
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\begin_layout Standard
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This equation shows that energy values are proportional to the square of
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This equation shows that confiend energy level values are proportional to
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the square of
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\begin_inset Formula $n$
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\end_inset
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@ -1198,6 +1199,63 @@ E_{2h}=5.45\times10^{-21}\unit{J}=0.034\unit{eV}
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\end_inset
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\end_layout
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\begin_layout Standard
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With the dimensions and first confined energy levels calculated, the final
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design for the quantum well can be seen in figure
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\begin_inset CommandInset ref
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LatexCommand ref
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reference "fig:quantum-well-design"
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plural "false"
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caps "false"
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noprefix "false"
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\end_inset
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.
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\end_layout
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\begin_layout Standard
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\begin_inset Float figure
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wide false
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sideways false
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status open
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\begin_layout Plain Layout
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\align center
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\begin_inset Graphics
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filename well-design.png
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lyxscale 30
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width 85col%
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\end_inset
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\end_layout
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\begin_layout Plain Layout
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\begin_inset Caption Standard
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\begin_layout Plain Layout
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InP/InGaAs/InP quantum well design
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\begin_inset CommandInset label
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LatexCommand label
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name "fig:quantum-well-design"
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\end_inset
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\end_layout
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\end_inset
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\end_layout
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\end_inset
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\end_layout
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\begin_layout Section
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@ -1239,7 +1297,7 @@ with
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\end_layout
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\begin_layout Standard
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Where
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Here
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\begin_inset Formula $A$
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\end_inset
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@ -1337,6 +1395,17 @@ noprefix "false"
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\end_inset
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has been set to 1 for the ground state.
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This function for the first excited state can be seen in figure
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\begin_inset CommandInset ref
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LatexCommand ref
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reference "fig:Probability-plot-n-2"
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plural "false"
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caps "false"
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noprefix "false"
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\end_inset
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.
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\end_layout
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\begin_layout Standard
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@ -1350,7 +1419,7 @@ status open
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\begin_inset Graphics
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filename probability-plot.png
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lyxscale 30
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width 100col%
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width 75col%
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\end_inset
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@ -1396,7 +1465,7 @@ status open
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\begin_inset Graphics
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filename probability-plot-with-n-2.png
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lyxscale 30
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width 100col%
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width 75col%
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\end_inset
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@ -1461,7 +1530,16 @@ noprefix "false"
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\end_inset
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gives the final probability function for the entire well:
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gives the final probability function for a distance across the well from
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\begin_inset Formula $x=0$
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\end_inset
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to
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\begin_inset Formula $x=x_{0}$
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\end_inset
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:
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\end_layout
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\begin_layout Standard
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@ -1476,15 +1554,7 @@ P\left(0\leq x\leq x_{0}\right)=\frac{1}{L}\left(x_{0}-\frac{L}{2n\pi}\sin\left(
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\end_layout
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\begin_layout Standard
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Where
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\begin_inset Formula $x_{0}$
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\end_inset
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is an arbitrary distance across the well.
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\end_layout
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\begin_layout Standard
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For an interval across the well, this becomes:
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For an arbitrary interval across the well, this becomes:
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\end_layout
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\begin_layout Standard
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@ -1498,6 +1568,37 @@ P\left(a\leq x\leq b\right)=\frac{1}{L}\left(\left(b-a\right)-\frac{L}{2n\pi}\le
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\end_layout
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\begin_layout Standard
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This equation can be utilised in order to find the probability of finding
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the electron between
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\begin_inset Formula $2\unit{nm}$
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\end_inset
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and
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\begin_inset Formula $4\unit{nm}$
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\end_inset
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and between
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\begin_inset Formula $6\unit{nm}$
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\end_inset
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and
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\begin_inset Formula $8\unit{nm}$
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\end_inset
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, the intervals for which can be seen plotted in figure
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\begin_inset CommandInset ref
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LatexCommand ref
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reference "fig:Probability-plot-with-bounds"
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plural "false"
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caps "false"
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noprefix "false"
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\end_inset
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.
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\end_layout
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\begin_layout Standard
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\begin_inset Float figure
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wide false
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@ -1509,7 +1610,7 @@ status open
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\begin_inset Graphics
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filename probability-plot-with-bounds.png
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lyxscale 30
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width 100col%
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width 75col%
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\end_inset
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@ -1576,7 +1677,7 @@ P\left(2\unit{nm}\leq x\leq4\unit{nm}\right)=\frac{1}{14.87\unit{nm}}\left(2\uni
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\begin_layout Standard
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\begin_inset Formula
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\[
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P\left(2\unit{nm}\leq x\leq4\unit{nm}\right)\thickapprox0.132
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P\left(2\unit{nm}\leq x\leq4\unit{nm}\right)\thickapprox0.0955
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\]
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\end_inset
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@ -1620,7 +1721,7 @@ P\left(6\unit{nm}\leq x\leq8\unit{nm}\right)=\frac{1}{14.87\unit{nm}}\left(2\uni
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\begin_layout Standard
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\begin_inset Formula
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\[
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P\left(6\unit{nm}\leq x\leq8\unit{nm}\right)\thickapprox0.132
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P\left(6\unit{nm}\leq x\leq8\unit{nm}\right)\thickapprox0.263
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\]
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\end_inset
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coursework.pdf
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coursework.pdf
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well-design.png
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well-design.png
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well-diagram.odg
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well-diagram.odg
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