doping{}¶
Specifications that define information on doping.
Note
Information on impurities  which can be donors or acceptors or fixed charge  is specified here: impurities{}
Syntaxes¶
Specifications of doping profile¶
The doping profile is assiged to a certain region.
The following syntaxes are put under structure{ region{ doping{} } }
constant
linear
gaussian1D
gaussian2D
gaussian3D
import
(import doping profile from external file) constant
constant doping profile over the region
 Example
constant{ name = "Si" # name of impurity conc = 1.0e18 # doping concentration [cm3] (applies to 1D, 2D and 3D) add = yes # (optional) yes or no (default = yes) }
Note
the name of impurities must be specified in the same input file in impurities{}.
 linear
linearly varying doping profile along the line from start to end point
 Example
linear{ name = "nSiinGaAs" # name of impurity conc = [1e18,2e18] # start and end value of doping concentration [cm3] 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 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 # (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 name = "pBinSi" # name of impurity conc = 1.0e18 # maximum of doping concentration [cm3] dose = 1e12 # dose of implant [cm2] (integrated density of gaussian function), typical ranges are from 1e11 to 1e16. # Either 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 = ... # (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) name = "pBinSi" # name of impurity conc = 1.0e18 # maximum of doping concentration [cm3] dose = 1.0 # dose of implant [cm1] (integrated density of 2D gaussian function) # Either dose or conc has to be specified, but not both simultaneously. x = 50.0 # x coordinate of Gauss center [nm] sigma_x = 5.0 # root mean square deviation in x direction [nm] y = 50.0 # y coordinate of Gauss center [nm] sigma_y = 5.0 # root mean square 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) name = "pBinSi" # name of impurity conc = 1.0e18 # maximum of doping concentration in [cm3] 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 # root mean square deviation in x direction [nm] y = 50.0 # y coordinate of Gauss center [nm] sigma_y = 5.0 # root mean square deviation in y direction [nm] z = 50.0 # z coordinate of Gauss center [nm] sigma_z = 5.0 # root mean square 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
import{ # import generation profile from external file name = "pBinSi" # impurity name uses imported alloy profile import_from = "import_doping_profile" # reference to imported data in import{}. The file being imported must have exactly one data component. }
Print out¶
These doping profile can be printed out by output_impurities{}
keyword under structure{}
:
 output_impurities{}
structure{ output_impurities{ # output doping concentration for each grid point in units of [10^18/(cm3)] boxes = yes/no # (optional) } }
Remove¶
It is also possible to remove a doping from a specific region.
 remove{}
structure{ region{ doping{ remove{} } # remove doping from this region, to keep certain regions free from doping. } # region } # structure
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.
Example¶
1D¶
Figure 2.2.3 shows two impurity profiles based on LSS theory. More information can be found in this tutorial: SchrödingerPoisson  A comparison to the tutorial file of Greg Snider’s code
For further details see for example: “Very brief Introduction to Ion Implantation for Semiconductor Manufacturing” by Gerhard Spitzlsperger.
3D¶
Figure 2.2.4 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.
The generation rate profile is constant between z = 10 nm and z = 25 nm with a rate of 1 x 1018 \([1/cm^3]\) . 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.
z = 0 ~ 10 nm 
z = 10 ~ 25 nm 
z = 25 ~ 45 nm 
z = 45 ~ 50 nm 

generation rate \([1/cm^3]\) 
0.0 
constant (1.0 × 1018) 
Gaussian (center = 25nm, sigma_z=6.0 nm) 
0.0 
Here is the structure
part of the input file that generates the above generation profile.
The whole input file is available here
.
structure{ output_impurities{} # output doping concentration for each grid point in units of [10^18/(cm3)] 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] } doping{ constant{ name = "nSiinGaAs" conc = 1.0E18 # doping concentration [1/cm3] (applies to 1D, 2D and 3D) } } } region{ binary{ name = GaAs } cuboid{ x = [0E0, 20E0] y = [0E0, 20E0] z = [25E0, 45E0] } doping{ gaussian1D{ name = "nSiinGaAs" conc = 1.0E18 # maximum of generation rate [1/cm3] 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] } } } }<>