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doping{}
Specifications that define information on doping.
The doping profile is assiged to a certain region.
It can be printed out
using the keyword
structure{ output_impurities{} }.
Note: Information on impurities - which can be donors, acceptors or fixed
charge - is specified here:
impurities{}
structure{
...
output_impurities{
# output doping concentration for each grid point in units of [1018/cm3]
boxes = yes/no
# (optional)
}
region{
...
doping{
constant{
name =
"Si"
# name of impurity
conc =
1.0e18
# [cm-3]
(applies to 1D, 2D and 3D)
add =
yes
# yes or no
(default = yes)
}
linear{
name =
"n-Si-in-GaAs"
#
conc =
[1e18,2e18]
# [cm-3]
x
= [50.0,100.0]
# x
coordinates of start and end point [nm]
y
= [50.0,100.0]
# y coordinates of start and end point [nm] (2D
or 3D only)
z
= [50.0,100.0]
# [nm] (3D only)
# This defines a doping
profile, which varies linearly along the line from the point (50,50,50)
to the point (100,100,100)
#
and stays constant in the perpendicular planes.
add =
yes
# yes or no
(default = yes)
}
gaussian1D{
#
name
=
"p-B-in-Si" #
conc =
1.0e18
# [cm-3]
dose
= 1e12
# dose of implant [cm-2] (integrated density of
gaussian function), typical ranges are
from 1e11 to
1e16.
#
dose or conc has to be specified, but not both
simultaneously.
# conc = dose / ( SQRT(2*pi) * sigma_x )
x
= 50.0
# x coordinate of Gauss center (ion's projected range Rp, i.e.
the depth where most ions stop) [nm]
sigma_x
=
5.0
# root mean square deviation in x direction (statistical fluctuation of Rp)
[nm]
y
= ... #
sigma_y =
...
#
z
= ... #
sigma_z =
...
#
# Only
one out of x, y, z and the appropriate standard deviation (sigma) has to be
specified.
add =
yes
# yes or no
(default = yes)
}
This profile corresponds to LSS theory (Lindhard, Scharff, Schiott
theory) - Gaussian distribution of ion implantation.
gaussian2D{
#
name
=
"p-B-in-Si" #
conc =
1.0e18
# [cm-3]
dose
= 1.0
# dose of implant [cm-1] (integrated density of
2D gaussian function)
#
dose or conc has to be specified, but not both
simultaneously.
x
= 50.0
#
sigma_x
=
5.0
# root mean square deviation in x direction [nm]
y
= 50.0
#
sigma_y =
5.0 #
z
= ... #
sigma_z =
...
#
# Exactly two out of x, y, z
and the appropriate standard deviations (sigma) have to be specified.
add =
yes
# yes or no
(default = yes)
}
gaussian3D{
#
name
=
"p-B-in-Si" #
conc =
1.0e18
# [cm-3]
dose
= 1.0
# dose of implant [dimensionless] (integrated density of 3D
gaussian function)
x
= 50.0
#
sigma_x
=
5.0
# root mean square deviation in x direction [nm]
y
= 50.0
#
sigma_y =
5.0 #
z
= 50.0
#
sigma_z =
5.0 #
# All three
x, y, z and the appropriate standard deviations (sigma) have to be specified.
add =
yes
# yes or no
(default = yes)
}
import{
# import generation profile from external file
name
=
"p-B-in-Si" #
import_from =
"import_doping_profile" #
import{}. The file being
imported must have exactly one data component.
}
More information
can be found in this tutorial:
1D
Schrödinger-Poisson tutorial.
"Very brief
Introduction to Ion Implantation for Semiconductor Manufacturing" by Gerhard
Spitzlsperger
} # doping
} # region
} # structure
It is also possible to remove a doping profile from a specific region.
structure{
region{
doping{
remove{} }
# remove doping from this region, to keep certain regions free from
doping.
} # region
} # structure
Examples (3D)
doping{
gaussian3D{
# three-dimensional Gaussian profile
name =
"dope_p" #
conc =
10.0e18
# [cm-3]
x =
30
y = 20
z = 20 #
position of the Gauss center
(x,y,z)=(30,20,20)
sigma_x =
5 sigma_y
= 2 sigma_z = 5
# Gauss width along x, y and z directions
}
gaussian2D{
#
name =
"dope_p" #
conc =
10.0e18
# [cm-3]
x =
10
y = 20
# position of the Gauss center
(x,y)=(10,20)
sigma_x =
5
sigma_y = 5
# Gauss width along x and y directions
}
}
- The following figure shows a 3D doping profile that is defined inside a 20 nm
x 20 nm x 50 nm cube where the 50 nm are the z direction. The doping profile is
homogeneous with respect to the (x,y) plane, it only varies along the z
direction.
The doping profile is constant between z
= 10 nm and z = 25 nm with a concentration of 1 x 1018 cm-3.
It has Gaussian shape from z = 25 nm to z = 45 nm (gaussian1D). It is
zero between z = 0 nm and z = 10 nm, as well as
between z = 45 nm and z = 50 nm.
If you want to obtain the input file that was used to obtain this 3D doping
profile plot (constant + Gaussian shape), please contact
stefan.birner@nextnano.de.
-> 3Ddoping_profile.in
doping{} and
generation{}
is always additive per default (add =
yes) (unless
import is different),
i.e. each profile adds to the already existing dopants/fixed charges/generation at a given point.
At the same time, using remove{}, all species of the already existing doping or generation concentrations can be removed.
However,
there is also the problem that remove{} removes all species of dopants/fixed charges at a given point.
Thus, removing e.g. only donors but not acceptors is difficult.
This problem is solved by the new "add = yes/no"
flag, which the user can specify for each profile (and thus for the species of that profile),
whether the profile should add to (which is the default) or
replace the already existing concentration of the profile species.
For
import{}, this flag has not been implemented yet.
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