adding graphs, beginning writing, added concentration/fermi level

This commit is contained in:
andy 2021-04-20 21:19:15 +01:00
parent 80a04c4b21
commit 4ce1569a86
36 changed files with 1057 additions and 72 deletions

View File

@ -8,20 +8,20 @@ close all; clear all; clc;
%% FLAGS & OPTIONS
%%%%%%%%%%%%%%%%%%%%%%%%%%%
DISPLAY_HZ = true;
DISPLAY_HZ = true; % convert rads back to Hz for presenting
MIN_F = 0;
MIN_F = 9;
MAX_F = 15; % Hz
F_TOTAL = 50;
F_TOTAL = 50; % number of points to generate
MAX_Y = 17; % carriers (m-2)
Y_TOTAL = 50;
MAX_Y = 18; % carriers (m-2)
Y_TOTAL = 50; % number of points to generate
%EXCITATION_TYPE = 'intra';
EXCITATION_TYPE = 'inter';
%EXCITATION_TYPE = 'all';
% EXCITATION_TYPE = 'intra';
% EXCITATION_TYPE = 'inter';
EXCITATION_TYPE = 'all';
t = 2.8; % eV
t = 2.8; % eV, energy scale for Fermi velocity
%%%%%%%%%%%%%%%%%%%%%%%%%%%
%% CALCULATE
@ -30,30 +30,66 @@ t = 2.8; % eV
f_vals = logspace(MIN_F, MAX_F, F_TOTAL); % hz
f_vals = f_vals .* (2*pi); % rads-1
carrier_vals = logspace(0, MAX_Y, Y_TOTAL); % m-2
%carrier_vals = carrier_vals + 273.15;
% below turns turns carrier densities into Fermi energies
fermi_vals = zeros(1, length(carrier_vals));
for carr=1:length(carrier_vals)
fermi_vals(carr) = fermi_from_carrier_density(carrier_vals(carr), ev_to_j(t));
end
% Carrier Density
%%%%%%%
% carrier_vals = logspace(0, MAX_Y, Y_TOTAL); % m-2
%
% % below turns turns carrier densities into Fermi energies
% fermi_vals = zeros(1, length(carrier_vals));
% for carr=1:length(carrier_vals)
% fermi_vals(carr) = fermi_from_carrier_density(carrier_vals(carr), ev_to_j(t));
% end
%
% % CALCULATE SHEET CONDUCTIVITY
% cond = zeros(length(f_vals),... % frequency
% length(fermi_vals),... % fermi
% 2); % intra/inter
% for freq=1:length(f_vals)
% for y=1:length(fermi_vals)
%
% cond(freq, y, :) = sheet_conductivity(f_vals(freq),... % omega (rads-1)
% fermi_vals(y),... % fermi_level (J)
% 300,... % temp (K)
% 5e-12); % scatter_lifetime (s)
% end
% end
% Temperature
%%%%%%%
temp_vals = linspace(0, 2230, Y_TOTAL); % K
% CALCULATE SHEET CONDUCTIVITY
cond = zeros(length(f_vals), % frequency
length(fermi_vals), % fermi
cond = zeros(length(f_vals),... % frequency
length(temp_vals),... % fermi
2); % intra/inter
for freq=1:length(f_vals)
for y=1:length(fermi_vals)
for y=1:length(temp_vals)
cond(freq, y, :) = sheet_conductivity(f_vals(freq), % omega (rads-1)
fermi_vals(y), % fermi_level (J)
300, % temp (K)
5e-12); % scatter_lifetime (s-1)
cond(freq, y, :) = sheet_conductivity(f_vals(freq),... % omega (rads-1)
fermi_from_carrier_density(1.3e13*10000, ev_to_j(t)),... % fermi_level (J)
temp_vals(y),... % temp (K)
5e-12); % scatter_lifetime (s)
end
end
% Scatter Lifetime
%%%%%%%
% scatt_vals = logspace(-11, -14, Y_TOTAL); % s-1
%
% % CALCULATE SHEET CONDUCTIVITY
% cond = zeros(length(f_vals),... % frequency
% length(scatt_vals),... % fermi
% 2); % intra/inter
% for freq=1:length(f_vals)
% for y=1:length(scatt_vals)
%
% cond(freq, y, :) = sheet_conductivity(f_vals(freq),... % omega (rads-1)
% fermi_from_carrier_density(1.3e13*10000, ev_to_j(t)),... % fermi_level (J), ttf = 1.3e13*10000, cocp2 = 2.2e13*10000
% 300,... % temp (K)
% scatt_vals(y)); % scatter_lifetime (s)
% end
% end
%%%%%%%%%%%%%%%%%%%%%%%%%%%
%% RENDER
%%%%%%%%%%%%%%%%%%%%%%%%%%%
@ -62,23 +98,37 @@ if DISPLAY_HZ % divide radians back to hertz
f_vals = f_vals ./ (2*pi);
end
y_vals = temp_vals;
% cond = sign(cond).*log10(abs(cond));
figure(1)
if EXCITATION_TYPE == 'intra'
surf(f_vals, carrier_vals, transpose(real(cond(:, :, 1))));
elseif EXCITATION_TYPE == 'inter'
surf(f_vals, carrier_vals, transpose(real(cond(:, :, 2))));
if strcmp(EXCITATION_TYPE, 'intra')
surf(f_vals, y_vals, transpose(real(cond(:, :, 1))));
title('2D Real Intraband Sheet Conductivity');
elseif strcmp(EXCITATION_TYPE, 'inter')
surf(f_vals, y_vals, transpose(real(cond(:, :, 2))));
title('2D Real Interband Sheet Conductivity');
else
surf(f_vals, carrier_vals, transpose(real(sum(cond, 3))));
surf(f_vals, y_vals, transpose(real(sum(cond, 3))));
title('2D Real Sheet Conductivity');
end
h = gca;
rotate3d on
grid;
colorbar;
set(h, 'xscale', 'log')
set(h, 'yscale', 'log')
title('2D Sheet Real Conductivity');
ylabel('Net Carrier Density (m-2)');
zlabel('Conductivity (S/m)');
axis tight;
set(gca, 'xscale', 'log')
% set(gca, 'yscale', 'log')
% set(gca, 'zscale', 'log')
set(gca, 'ColorScale', 'log')
% ylabel('Net Carrier Density (m^{-2})');
ylabel('Temperature (K)');
% ylabel('Scatter Lifetime (s)');
zlabel('Conductivity (S)');
if DISPLAY_HZ
xlabel('Frequency (Hz)');
else
@ -86,23 +136,32 @@ else
end
figure(2)
if EXCITATION_TYPE == 'intra'
surf(f_vals, carrier_vals, transpose(imag(cond(:, :, 1))));
elseif EXCITATION_TYPE == 'inter'
surf(f_vals, carrier_vals, transpose(imag(cond(:, :, 2))));
if strcmp(EXCITATION_TYPE, 'intra')
surf(f_vals, y_vals, transpose(imag(cond(:, :, 1))));
title('2D Imaginary Intraband Sheet Conductivity');
elseif strcmp(EXCITATION_TYPE, 'inter')
surf(f_vals, y_vals, transpose(imag(cond(:, :, 2))));
title('2D Imaginary Interband Sheet Conductivity');
else
surf(f_vals, carrier_vals, transpose(imag(sum(cond, 3))));
surf(f_vals, y_vals, transpose(imag(sum(cond, 3))));
title('2D Imaginary Sheet Conductivity');
end
surf(f_vals, carrier_vals, transpose(imag(sum(cond, 3))));
h = gca;
rotate3d on
grid;
colorbar;
set(h, 'xscale', 'log')
set(h, 'yscale', 'log')
title('2D Sheet Imaginary Conductivity');
ylabel('Net Carrier Density (m-2)');
zlabel('Conductivity (S/m)');
axis tight;
set(gca, 'xscale', 'log')
% set(gca, 'yscale', 'log')
% set(gca, 'zscale', 'log')
% set(gca, 'ColorScale', 'log')
% ylabel('Net Carrier Density (m^{-2})');
ylabel('Temperature (K)');
% ylabel('Scatter Lifetime (s)');
zlabel('Conductivity (S)');
if DISPLAY_HZ
xlabel('Frequency (Hz)');
else

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@ -8,14 +8,17 @@ close all; clear all; clc;
%% FLAGS & OPTIONS
%%%%%%%%%%%%%%%%%%%%%%%%%%%
DISPLAY_HZ = true;
DISPLAY_HZ = true; % convert rads back to Hz for presenting
MIN_F = 9;
MAX_F = 15;
F_TOTAL = 1e2;
F_TOTAL = 1e2; % number of points to generate
%EXCITATION_TYPE = 'intra';
EXCITATION_TYPE = 'inter';
%EXCITATION_TYPE = 'all';
% EXCITATION_TYPE = 'intra';
% EXCITATION_TYPE = 'inter';
EXCITATION_TYPE = 'all';
TWO_SERIES = true; % for comparing two dopants
%%%%%%%%%%%%%%%%%%%%%%%%%%%
%% CALCULATE
@ -27,10 +30,20 @@ x_vals = x_vals .* (2*pi); % rads-1
% CALCULATE SHEET CONDUCTIVITY
cond = zeros(length(x_vals), 2);
for x=1:length(x_vals)
cond(x, :) = sheet_conductivity(x_vals(x), % omega (rads-1)
fermi_from_carrier_density(2.2e17, ev_to_j(2.8)), % fermi_level (J)
300, % temp (K)
0.135e-12); % scatter_lifetime (s-1)
cond(x, :) = sheet_conductivity(x_vals(x),... % omega (rads-1)
fermi_from_carrier_density(1.3e13*10000, ev_to_j(3)),... % fermi_level (J)
300,... % temp (K)
1e-12); % scatter_lifetime (s)
end
if TWO_SERIES
cond2 = zeros(length(x_vals), 2);
for x=1:length(x_vals)
cond2(x, :) = sheet_conductivity(x_vals(x),... % omega (rads-1)
fermi_from_carrier_density(2.2e13*10000, ev_to_j(3)),... % fermi_level (J)
300,... % temp (K)
1e-12); % scatter_lifetime (s)
end
end
if DISPLAY_HZ % divide radians back to hertz
@ -41,24 +54,59 @@ end
%% RENDER
%%%%%%%%%%%%%%%%%%%%%%%%%%%
RE_COLOUR = 'r';
IM_COLOUR = 'r--';
RE_COLOUR2 = 'b';
IM_COLOUR2 = 'b--';
LW = 1.5;
figure(1);
hold on;
%plot(x_vals, real(cond));
if EXCITATION_TYPE == 'intra'
semilogx(x_vals, real(cond(:, 1)));
semilogx(x_vals, imag(cond(:, 1)));
elseif EXCITATION_TYPE == 'inter'
semilogx(x_vals, real(cond(:, 2)));
semilogx(x_vals, imag(cond(:, 2)));
% INTRA
if strcmp(EXCITATION_TYPE, 'intra')
plot(x_vals, real(cond(:, 1)), RE_COLOUR, 'LineWidth', LW);
plot(x_vals, imag(cond(:, 1)), IM_COLOUR, 'LineWidth', LW);
if TWO_SERIES
plot(x_vals, real(cond2(:, 1)), RE_COLOUR2, 'LineWidth', LW);
plot(x_vals, imag(cond2(:, 1)), IM_COLOUR2, 'LineWidth', LW);
end
title('2D Intraband Sheet Conductivity');
% INTER
elseif strcmp(EXCITATION_TYPE, 'inter')
plot(x_vals, real(cond(:, 2)), RE_COLOUR, 'LineWidth', LW);
plot(x_vals, imag(cond(:, 2)), IM_COLOUR, 'LineWidth', LW);
if TWO_SERIES
plot(x_vals, real(cond2(:, 2)), RE_COLOUR2, 'LineWidth', LW);
plot(x_vals, imag(cond2(:, 2)), IM_COLOUR2, 'LineWidth', LW);
end
title('2D Interband Sheet Conductivity');
% COMPLEX
else
semilogx(x_vals, real(sum(cond, 2)));
semilogx(x_vals, imag(sum(cond, 2)));
plot(x_vals, real(sum(cond, 2)), RE_COLOUR, 'LineWidth', LW);
plot(x_vals, imag(sum(cond, 2)), IM_COLOUR, 'LineWidth', LW);
if TWO_SERIES
plot(x_vals, real(sum(cond2, 2)), RE_COLOUR2, 'LineWidth', LW);
plot(x_vals, imag(sum(cond2, 2)), IM_COLOUR2, 'LineWidth', LW);
end
title('2D Sheet Conductivity');
end
legend('Real', 'Imaginary');
set(gca,'Xscale','log')
% set(gca,'Yscale','log')
axis tight
if TWO_SERIES
legend('Real TTF', 'Imaginary TTF', 'Real CoCp2', 'Imaginary CoCp2');
else
legend('Real', 'Imaginary');
end
grid;
title('2D Sheet Conductivity');
ylabel('Conductivity (S/m)');
ylabel('Conductivity (S)');
if DISPLAY_HZ
xlabel('Frequency (Hz)');
else

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@ -0,0 +1,52 @@
%% fermi_conc.m
%%
%% present fermi levels for different carrier concentrations
close all; clear all; clc;
%%%%%%%%%%%%%%%%%%%%%%%%%%%
%% FLAGS & OPTIONS
%%%%%%%%%%%%%%%%%%%%%%%%%%%
MIN_CONC = 0;
MAX_CONC = 20;
X_TOTAL = 1e2; % number of points to generate
DISP_EV = true;
%%%%%%%%%%%%%%%%%%%%%%%%%%%
%% CALCULATE
%%%%%%%%%%%%%%%%%%%%%%%%%%%
x_vals = logspace(MIN_CONC, MAX_CONC, X_TOTAL); % hz
% CALCULATE SHEET CONDUCTIVITY
energy = zeros(1, length(x_vals));
for x=1:length(x_vals)
temp = fermi_from_carrier_density(x_vals(x), ev_to_j(2.8)); % scatter_lifetime (s)
if DISP_EV
temp = j_to_ev(temp);
end
energy(1, x) = temp;
end
%%%%%%%%%%%%%%%%%%%%%%%%%%%
%% RENDER
%%%%%%%%%%%%%%%%%%%%%%%%%%%
% INTRA
plot(x_vals, energy, 'LineWidth', 1.5);
title('Fermi level for differing carrier concentrations');
set(gca,'Xscale','log')
set(gca,'Yscale','log')
% axis tight
grid;
xlabel('Carrier Concentration (m^{-2})');
if DISP_EV
ylabel('Fermi Energy (eV)');
else
ylabel('Fermi Energy (J)');
end

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@ -1,4 +1,5 @@
function eV = j_to_ev(j)
%J_TO_EV Transform Joules into electron-volts
eV = j / 1.602e-19;
end

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@ -0,0 +1,58 @@
@article{yao,
author = {Yao, Yu and Kats, Mikhail A. and Genevet, Patrice and Yu, Nanfang and Song, Yi and Kong, Jing and Capasso, Federico},
doi = {10.1021/nl3047943},
issn = {1530-6984},
journal = {Nano Letters},
note = {doi: 10.1021/nl3047943},
number = {3},
pages = {1257--1264},
publisher = {American Chemical Society},
risfield_0_da = {2013/03/13},
risfield_1_t2 = {Nano Letters},
title = {Broad Electrical Tuning of Graphene-Loaded Plasmonic Antennas},
url = {https://pubs.acs.org/doi/10.1021/nl3047943},
urldate = {2021-04-19},
volume = {13},
year = {2013}
}
@article{david-paper,
author = {Samuels, Alexander J. and Carey, J. David},
doi = {10.1021/acsami.5b05140},
issn = {1944-8244},
journal = {ACS Applied Materials \& Interfaces},
note = {doi: 10.1021/acsami.5b05140},
number = {40},
pages = {22246--22255},
publisher = {American Chemical Society},
risfield_0_da = {2015/10/14},
risfield_1_t2 = {ACS Applied Materials \& Interfaces},
title = {Engineering Graphene Conductivity for Flexible and High-Frequency Applications},
url = {https://pubs.acs.org/doi/pdf/10.1021/acsami.5b05140},
urldate = {2021-04-20},
volume = {7},
year = {2015}
}
@article{graphene-high-temp,
abstract = {Heat has always been a killing matter for traditional semiconductor machines. The underlining physical reason is that the intrinsic carrier density of a device made from a traditional semiconductor material increases very fast with a rising temperature. Once reaching a temperature, the density surpasses the chemical doping or gating effect, any p-n junction or transistor made from the semiconductor will fail to function. Here, we measure the intrinsic Fermi level (|EF| = 2.93 kBT) or intrinsic carrier density (nin = 3.87 {\texttimes} 10(6) cm(-2)K(-2){\textcdot} T(2)), carrier drift velocity, and G mode phonon energy of graphene devices and their temperature dependencies up to 2400 K. Our results show intrinsic carrier density of graphene is an order of magnitude less sensitive to temperature than those of Si or Ge, and reveal the great potentials of graphene as a material for high temperature devices. We also observe a linear decline of saturation drift velocity with increasing temperature, and identify the temperature coefficients of the intrinsic G mode phonon energy. Above knowledge is vital in understanding the physical phenomena of graphene under high power or high temperature.},
author = {Yin, Yan and Cheng, Zengguang and Wang, Li and Jin, Kuijuan and Wang, Wenzhong},
doi = {10.1038/srep05758},
issn = {2045-2322},
journal = {Scientific reports},
month = jul,
pages = {5758--5758},
publisher = {Nature Publishing Group},
risfield_0_db = {PubMed},
risfield_1_la = {eng},
risfield_2_an = {25044003},
risfield_3_u1 = {25044003[pmid]},
risfield_4_u2 = {PMC4104577[pmcid]},
risfield_5_u4 = {srep05758[PII]},
title = {Graphene, a material for high temperature devices--intrinsic carrier density, carrier drift velocity, and lattice energy},
url = {https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4104577},
urldate = {2021-04-20},
volume = {4},
year = {2014}
}

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@ -21,7 +21,7 @@ minimalistic
todonotes
\end_modules
\maintain_unincluded_children false
\language english
\language british
\language_package default
\inputencoding auto
\fontencoding global
@ -97,7 +97,7 @@ todonotes
\defskip medskip
\is_math_indent 0
\math_numbering_side default
\quotes_style english
\quotes_style british
\dynamic_quotes 0
\papercolumns 1
\papersides 1
@ -117,7 +117,7 @@ todonotes
\begin_layout Title
\size giant
Graphene Investigations & Conductivity Modelling
Graphene Applications & Conductivity Modelling At High Frequencies
\end_layout
\begin_layout Author
@ -272,18 +272,778 @@ setcounter{page}{1}
Introduction
\end_layout
\begin_layout Standard
Graphene is a 2D allotrope of carbon with
\end_layout
\begin_layout Standard
This work explores the suitability of graphene for high frequency applications.
Section
\begin_inset CommandInset ref
LatexCommand ref
reference "sec:Applications"
plural "false"
caps "false"
noprefix "false"
\end_inset
presents two applications of graphene that take advantage of it's behaviour
at high frequencies.
Section
\begin_inset CommandInset ref
LatexCommand ref
reference "sec:Sheet-Conductivity-Modelling"
plural "false"
caps "false"
noprefix "false"
\end_inset
presents an investigation into the 2D sheet conductivity of the material.
\end_layout
\begin_layout Section
Graphene Applications
Applications
\begin_inset CommandInset label
LatexCommand label
name "sec:Applications"
\end_inset
\end_layout
\begin_layout Section
Sheet Conductivity Modelling
\begin_inset CommandInset label
LatexCommand label
name "sec:Sheet-Conductivity-Modelling"
\end_inset
\end_layout
\begin_layout Standard
This section presents a model for graphene's high frequency conductivity
using the equation below below
\begin_inset CommandInset citation
LatexCommand cite
key "yao"
literal "false"
\end_inset
.
\end_layout
\begin_layout Standard
\begin_inset Formula
\begin{multline}
\sigma_{s}\left(\omega\right)=\frac{2ie^{2}k_{B}T}{\pi\hbar^{2}\left(\omega+\nicefrac{i}{\tau}\right)}\ln\left(2\cosh\left(\frac{E_{F}}{2k_{B}T}\right)\right)\\
+\frac{e^{2}}{4\hbar}\left(\frac{1}{2}+\frac{1}{\pi}\tan^{-1}\left(\frac{\hbar\omega-2E_{F}}{2k_{B}T}\right)-\frac{i}{2\pi}\ln\left(\frac{\left(\hbar\omega+2E_{F}\right)^{2}}{\left(\hbar\omega-2E_{F}\right)^{2}+4\left(k_{B}T\right)^{2}}\right)\right)\label{eq:2d-conductivity}
\end{multline}
\end_inset
\end_layout
\begin_layout Standard
Taking this equation, the first term accounts for the intraband transitions
while the latter term refers to the interband transitions
\begin_inset CommandInset citation
LatexCommand cite
key "david-paper"
literal "false"
\end_inset
\begin_inset Flex TODO Note (Margin)
status open
\begin_layout Plain Layout
cite
\end_layout
\end_inset
.
These two contributions are separated for reference below,
\end_layout
\begin_layout Standard
\begin_inset Formula
\begin{equation}
\sigma_{s}^{intra}\left(\omega\right)=\frac{2ie^{2}k_{B}T}{\pi\hbar^{2}\left(\omega+\nicefrac{i}{\tau}\right)}\ln\left(2\cosh\left(\frac{E_{F}}{2k_{B}T}\right)\right)\label{eq:intra-conductivity}
\end{equation}
\end_inset
\end_layout
\begin_layout Standard
\begin_inset Formula
\begin{equation}
\sigma_{s}^{inter}\left(\omega\right)=\frac{e^{2}}{4\hbar}\left(\frac{1}{2}+\frac{1}{\pi}\tan^{-1}\left(\frac{\hbar\omega-2E_{F}}{2k_{B}T}\right)-\frac{i}{2\pi}\ln\left(\frac{\left(\hbar\omega+2E_{F}\right)^{2}}{\left(\hbar\omega-2E_{F}\right)^{2}+4\left(k_{B}T\right)^{2}}\right)\right)\label{eq:inter-conductivity}
\end{equation}
\end_inset
\end_layout
\begin_layout Standard
Equation
\begin_inset CommandInset ref
LatexCommand ref
reference "eq:2d-conductivity"
plural "false"
caps "false"
noprefix "false"
\end_inset
was implemented in MatLab, see listing
\begin_inset CommandInset ref
LatexCommand ref
reference "calculation_function"
plural "false"
caps "false"
noprefix "false"
\end_inset
, such that the inter and intraband contributions were returned separately.
This allowed for displaying both aspects independently or together by summing.
From the function it can be seen that the variables are AC frequency,
\begin_inset Formula $\omega$
\end_inset
, the Fermi energy level,
\begin_inset Formula $E_{F}$
\end_inset
, the temperature,
\begin_inset Formula $T$
\end_inset
, and the scatter lifetime,
\begin_inset Formula $\tau$
\end_inset
.
These were varied within reasonable ranges in order to investigate how
such variations affect the conductivity, both as a whole and individually.
\end_layout
\begin_layout Subsection
Results
\end_layout
\begin_layout Standard
To validate the model, values for TTF and CoCp
\begin_inset script subscript
\begin_layout Plain Layout
2
\end_layout
\end_inset
doping taken from
\begin_inset CommandInset citation
LatexCommand citet
key "david-paper"
literal "false"
\end_inset
(see table
\begin_inset CommandInset ref
LatexCommand ref
reference "tab:david-values"
plural "false"
caps "false"
noprefix "false"
\end_inset
) were simulated and can be seen presented in figure
\begin_inset CommandInset ref
LatexCommand ref
reference "fig:david-simulation-conductivity"
plural "false"
caps "false"
noprefix "false"
\end_inset
.
Similarly to the original, the real component can be seen to begin between
40 and 70 mS before declining to around 0.5
\begin_inset Formula $\mu S$
\end_inset
.
This decline occurs between 20 GHz and 2 THz.
The imaginary component peaks over the same frequency band that the real
component declines and the two intersect at around 150 GHz with a conductance
of 31 mS with CoCp
\begin_inset script subscript
\begin_layout Plain Layout
2
\end_layout
\end_inset
and 24 mS for TTF.
\end_layout
\begin_layout Standard
\begin_inset Float table
wide false
sideways false
status open
\begin_layout Plain Layout
\noindent
\align center
\begin_inset Tabular
<lyxtabular version="3" rows="3" columns="3">
<features tabularvalignment="middle">
<column alignment="center" valignment="top">
<column alignment="center" valignment="top">
<column alignment="center" valignment="top">
<row>
<cell alignment="center" valignment="top" topline="true" bottomline="true" leftline="true" usebox="none">
\begin_inset Text
\begin_layout Plain Layout
Dopant
\end_layout
\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" bottomline="true" leftline="true" usebox="none">
\begin_inset Text
\begin_layout Plain Layout
Carrier Concentration (cm
\begin_inset script superscript
\begin_layout Plain Layout
-2
\end_layout
\end_inset
)
\end_layout
\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" bottomline="true" leftline="true" rightline="true" usebox="none">
\begin_inset Text
\begin_layout Plain Layout
Fermi Level (eV)
\end_layout
\end_inset
</cell>
</row>
<row>
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text
\begin_layout Plain Layout
TTF
\end_layout
\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text
\begin_layout Plain Layout
1.3 x 10
\begin_inset script superscript
\begin_layout Plain Layout
13
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\end_inset
\end_layout
\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
\begin_inset Text
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0.41
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CoCp
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2
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2.2 x 10
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13
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0.53
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With Fermi velocity energy scale,
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= 3 eV
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Carrier concentration values for dopants from
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and the Fermi levels derived from the model, see figure
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Complex conductivity for TTF and CoCp
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2
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doping at 300 K with a scatter lifetime of 1 ps
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The Fermi level used to calculate conductance (listing
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) was derived from the net carrier concentration as a result of doping,
see listing
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.
The non-linear function can be seen modelled in figure
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Fermi level associated with different carrier concentrations
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Carrier Density
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influences conductivity can be seen in the surfaces of figure
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Complex conductivity over frequency for different carrier densities
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Temperature
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Values from 0 to the breakdown temperature of graphene, 2230 K
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, were varied in order to investigate the effect on conductance.
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Complex conductivity over frequency for different temperatures
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Scattering Lifetime
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Complex conductivity over frequency for different scattering lifetimes
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\begin_layout Subsection
Discussion
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\begin_layout Section
Conclusion
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7
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