2.8.10. structure{ region{ generation{ } injection{ } } }
Specifications that define information on generation and injection rates.
Injection refers here to explicit electron injection e.g. by electron beam (no holes for now). It used the same keywords as generation. Similarly to generation, this only has an effect when the current equations are solved.
Attention
The injection{} group can be used in exactly the same way as the generation{} group.
The generation rate profile is assiged to a certain region.
Nested keywords
constant{ }
constant generation rate over the region
Example
constant{
rate = 1.0e18 # generation rate [1/cm³s] (applies to 1D, 2D and 3D)
add = yes # (optional) yes or no (default = yes)
}
linear{ }
linearly varying generation rate along the line from start to end point
Example
linear{
rate = [1e18,2e18] # start and end value of generation rate [1/cm3s]
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] # z coordinates of start and end point [nm] (3D only)
# This defines a generation rate 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 # (optional) yes or no (default = yes)
}
gaussian1D{ }
Gaussian distribution function in one direction, constant in perpendicular directions
Example
gaussian1D{ # Gaussian distribution function in one direction, constant in perpendicular directions
rate = 1.0e18 # maximum of generation rate [1/cm3s]
dose = 1e12 # dose of implant [cm-2] (integrated density of Gaussian function), typical ranges are from 1e11 to 1e16.
# Either rate or dose has to be specified, but not both simultaneously.
# rate = 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 # standard deviation in x direction (statistical fluctuation of Rp) [nm]
y = ... # (2D or 3D only)
sigma_y = ... #
z = ... # (3D only)
sigma_z = ... #
# Only one out of x, y, z and the appropriate standard deviation (sigma) has to be specified.
add = yes # (optional) yes or no (default = yes)
}
Note
This profile corresponds to LSS theory (Lindhard, Scharff, Schiott theory) for doping - Gaussian distribution of ion implantation.
gaussian2D{ }
Gaussian distribution function in two directions, constant in perpendicular direction (2D or 3D only)
Example
gaussian2D{ # Gaussian distribution function in two directions, constant in perpendicular direction (2D or 3D only)
rate = 1.0e18 # maximum of generation rate [1/cm3s]
dose = 1.0 # dose of implant [cm-1] (integrated density of 2D Gaussian function)
# Either rate or dose has to be specified, but not both simultaneously.
x = 50.0 # x coordinate of Gauss center [nm]
sigma_x = 5.0 # standard deviation in x direction [nm]
y = 50.0 # y coordinate of Gauss center [nm]
sigma_y = 5.0 # standard deviation in y direction [nm]
z = ... # (3D only)
sigma_z = ... #
# Exactly two out of x, y, z and the appropriate standard deviations (sigma) have to be specified.
add = yes # (optional) yes or no (default = yes)
}
gaussian3D{ }
Gaussian distribution function in three directions (3D only)
Example
gaussian3D{ # Gaussian distribution function in three directions (3D only)
rate = 1.0e18 # maximum of generation rate in [1/cm3s]
dose = 1.0 # dose of implant [dimensionless] (integrated density of 3D Gaussian function)
x = 50.0 # x coordinate of Gauss center [nm]
sigma_x = 5.0 # standard deviation in x direction [nm]
y = 50.0 # y coordinate of Gauss center [nm]
sigma_y = 5.0 # standard deviation in y direction [nm]
z = 50.0 # z coordinate of Gauss center [nm]
sigma_z = 5.0 # standard deviation in z direction [nm]
# All three x, y, z and the appropriate standard deviations (sigma) have to be specified.
add = yes # (optional) yes or no (default = yes)
}
import{ }
import generation profile from external file
Note
These generation rate profile can be printed out by output_generation{} under structure{ }
Example
import{ # import generation profile from external file.
import_from = "import_generation_profile" # reference to imported data in import{ }. The file being imported must have exactly one data component.
}
remove{ }
It is also possible to remove a generation rate from a specific region.
Note
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.
structure{
region{
generation{ remove{} } # remove generation rate from this region, to keep certain regions free from generation rate.
} # region
} # structure
Example for 3D simulations
Figure 2.8.10.1 shows a 3D generation profile that is defined inside a 20 nm x 20 nm x 50 nm cube where the 50 nm are the z direction. The generation rate profile is homogeneous with respect to the (x,y) plane, it only varies along the z direction.
Figure 2.8.10.1 Three-dimensional generation rate profile. (Image generated by ParaView.)
The generation rate profile is constant between z = 10 nm and z = 25 nm with a rate of 1 x 1018 \([1/(cm^3s)]\). 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.
z = 0 ~ 10 nm |
z = 10 ~ 25 nm |
z = 25 ~ 45 nm |
z = 45 ~ 50 nm |
|
generation rate \([1/(cm^3s)]\) |
0.0 |
constant (1.0 × 1018) |
Gaussian (center = 25 nm, \(\sigma_z=6.0\) nm) |
0.0 |
Here is the structure part of the input file that generates the above generation profile.
structure{
output_generation{} # output generation rate for each grid point in units of [10^18/(cm3 s)]
region{ # default material
everywhere{}
binary{ name = GaAs }
contact{ name = contact }
}
region{
binary{ name = GaAs }
cuboid{
x = [0E0, 20E0]
y = [0E0, 20E0]
z = [0E0, 10E0]
}
}
region{
binary{ name = GaAs }
cuboid{
x = [0E0, 20E0]
y = [0E0, 20E0]
z = [10E0, 25E0]
}
generation{
constant{
rate = 1.0E18 # generation rate [1/cm3s] (applies to 1D, 2D and 3D)
}
}
}
region{
binary{ name = GaAs }
cuboid{
x = [0E0, 20E0]
y = [0E0, 20E0]
z = [25E0, 45E0]
}
generation{
gaussian1D{
rate = 1.0E18 # maximum of generation rate [1/cm3s]
z = 25 # z coordinate of Gauss center (ion's projected range Rp, i.e. the depth where most ions stop) [nm]
sigma_z = 6.0 # root mean square deviation in z direction (statistical fluctuation of Rp) [nm]
}
}
}
}
Last update: 2025-09-05