# Implementation of Implantation Depth Profile@

In $$\mathcal{KSOME}$$, implantation depth profiles can be implemented by using the fake defect types. These defect types do not interact with other defect types in any way. Their sole purpose is to produce other defect types according to their production rates. These fake defects are placed at various depths ($$z$$) and will create (real) defect types at random locations at those depths.

• input configuration — To place the fake defects at various depths.
• activated event DB — To specify the production rates of various (real) defect types.
• reaction event DB — To specify the type and size of the newly created defects.

The implementation of the implantation depth profile for 100 eV helium atoms impinging on a (100) tungsten surface is described below to show ow it is done.

## Implantation Depth Profile@

First up one needs to make sure that the implantation depth profile is normalized. In this example, a normalized implantation depth profile for 100 eV helium on a W (100) shown below will be used.

Figure 1 Normalized implantation depth profile for 100 eV helium normal incident on a W(100) surface as obtained by MD simulations1, 2.
(Plot is interactive. Drag-zoom using your mouse.

## Input Configuration@

Below is a snap shot of the first 34 lines (highlighted) of input configuration (simulation cell) for the implantation profile shown above. Here, only the first 34 lines corresponding to 34 layers from the surface.

Description

• A fake defect is placed at each layer (z-coordinate).
• Each of these fake defects creates a helium atom at a random $$(x,y)$$ coordinates in the same layer as the fake defect.
• Each individual fake defect is associated with a helium production rate such that He atoms are produced according the implantation profile.
He Implantation Depth Profile for W(100) Surface
Implantation Energy = 100 eV
Implantation Surface: Z = 0
# hash symbol marks the end of comment lines
0
1600    1600    800
94
4    7
0    0    1    2    1    0.1    5    1
0    0    2    2    1    0.1    5    2
0    0    3    2    1    0.1    5    3
0    0    4    2    1    0.1    5    4
0    0    5    2    1    0.1    5    5
0    0    6    2    1    0.1    5    6
0    0    7    2    1    0.1    5    7
0    0    8    2    1    0.1    5    8
0    0    9    2    1    0.1    5    9
0    0    10    2    1    0.1    5    10
0    0    11    2    1    0.1    5    11
0    0    12    2    1    0.1    5    12
0    0    13    2    1    0.1    5    13
0    0    14    2    1    0.1    5    14
0    0    15    2    1    0.1    5    15
0    0    16    2    1    0.1    5    16
0    0    17    2    1    0.1    5    17
0    0    18    2    1    0.1    5    18
0    0    19    2    1    0.1    5    19
0    0    20    2    1    0.1    5    20
0    0    21    2    1    0.1    5    21
0    0    22    2    1    0.1    5    22
0    0    23    2    1    0.1    5    23
0    0    24    2    1    0.1    5    24
0    0    25    2    1    0.1    5    25
0    0    26    2    1    0.1    5    26
0    0    27    2    1    0.1    5    27
0    0    28    2    1    0.1    5    28
0    0    29    2    1    0.1    5    29
0    0    30    2    1    0.1    5    30
0    0    31    2    1    0.1    5    31
0    0    32    2    1    0.1    5    32
0    0    33    2    1    0.1    5    33
0    0    34    2    1    0.1    5    34


Fake Defects

• It is a defect type that does not interact with any other defect types.
• Its sole purpose of it to create defects of various types and sizes based on their production rates.

Hardwired Aspects

• Information on fake defects is inputted via the input configuration (simulation cell) file.
• Both real and fake defects are inputted used the same input file.
• $$(x, y, z)$$ coordinates of fake defects control the where or how the newly created defects are placed as described below.
• To identify fake defects they were given a defect type between 0 and 1. However, users are allowed other IDs.
• Interactions between defects are specified in the reaction event database

## Activated Event DB@

• Below is a snap shot of the first 34 lines (from line №.7) of activated event database.
• Each fake defect is associated with the He implantation rate (He/s) and the production probability.
• f is key alphabet corresponding to the defect creation.
• The size and the type of the new defect created is specified in the reaction event database.
• Total sum probabilities on column 11 should be equal to one.
For W(100) Surface
Implantation Energy = 100 eV, Implantation Surface: Z = 0
# hash symbol marks the end comment lines
4        7
201
2    1    0.1    5    1     1    f    1    6.43E+07    1    0
2    1    0.1    5    2     1    f    1    6.43E+07    1    0
2    1    0.1    5    3     1    f    1    6.43E+07    1    0.0081807
2    1    0.1    5    4     1    f    1    6.43E+07    1    0.016728
2    1    0.1    5    5     1    f    1    6.43E+07    1    0.0337
2    1    0.1    5    6     1    f    1    6.43E+07    1    0.038828
2    1    0.1    5    7     1    f    1    6.43E+07    1    0.041636
2    1    0.1    5    8     1    f    1    6.43E+07    1    0.050549
2    1    0.1    5    9     1    f    1    6.43E+07    1    0.053846
2    1    0.1    5    10    1    f    1    6.43E+07    1    0.050305
2    1    0.1    5    11    1    f    1    6.43E+07    1    0.056532
2    1    0.1    5    12    1    f    1    6.43E+07    1    0.052747
2    1    0.1    5    13    1    f    1    6.43E+07    1    0.054701
2    1    0.1    5    14    1    f    1    6.43E+07    1    0.04652
2    1    0.1    5    15    1    f    1    6.43E+07    1    0.044933
2    1    0.1    5    16    1    f    1    6.43E+07    1    0.040781
2    1    0.1    5    17    1    f    1    6.43E+07    1    0.037607
2    1    0.1    5    18    1    f    1    6.43E+07    1    0.032234
2    1    0.1    5    19    1    f    1    6.43E+07    1    0.036142
2    1    0.1    5    20    1    f    1    6.43E+07    1    0.028449
2    1    0.1    5    21    1    f    1    6.43E+07    1    0.02735
2    1    0.1    5    22    1    f    1    6.43E+07    1    0.025763
2    1    0.1    5    23    1    f    1    6.43E+07    1    0.01978
2    1    0.1    5    24    1    f    1    6.43E+07    1    0.01746
2    1    0.1    5    25    1    f    1    6.43E+07    1    0.015873
2    1    0.1    5    26    1    f    1    6.43E+07    1    0.014652
2    1    0.1    5    27    1    f    1    6.43E+07    1    0.013675
2    1    0.1    5    28    1    f    1    6.43E+07    1    0.011966
2    1    0.1    5    29    1    f    1    6.43E+07    1    0.010134
2    1    0.1    5    30    1    f    1    6.43E+07    1    0.010745
2    1    0.1    5    31    1    f    1    6.43E+07    1    0.0083028
2    1    0.1    5    32    1    f    1    6.43E+07    1    0.0083028
2    1    0.1    5    33    1    f    1    6.43E+07    1    0.0075702
2    1    0.1    5    34    1    f    1    6.43E+07    1    0.0075702


In the snapshot of the database:

• The total production rate = $$6.43 \times 10^7$$ He/s (6.43E+07) (in column 9)
• For example, on line № 8, i.e. at $$z = 3$$, the fake defect is associated with the helium production rate of $$5.26 \times 10^5$$ He/s, which is the product of $$6.43 \times 10^7$$ He/s and the probability 0.0081807.
• The restriction is on the z-coordinate of the fake defects. Within the z-layer, a fake defect can be placed anywhere.

Placement of Newly Created Defects

• A fake defect can be associated with production of multiple defect types and of various sizes simultaneously.
• Locations of simultaneously created defects depends on the values of the $$(x, y, z)$$ coordinates of the parent fake defect.
• The location of the newly created defects follows the following rules (the top two are the unique ones)
• If the coordinates of a fake defect are $$(x_{\!_f}, y_{\!_f}, z_{\!_f}) = (0, 0, 0)$$, then the coordinates of the newly created defect(s) is placed at a random $$(x_n, y_n, z_n)$$ location.
• If the coordinates of a fake defect are $$(x_{\!_f},y_{\!_f},z_{\!_f}) = (0, 0, z_{\!_f})$$ and $$z_{\!_f} \ne 0$$, then the coordinates of the newly created defect(s) is placed at a random $$(x_n, y_n)$$ with $$z_n = z_{\!_f}$$, that is, at $$(x_n, y_n, z_n = z_f)$$.
• If the coordinates of a fake defect are $$(x_{\!_f}, y_{\!_f}, z_{\!_f}) = (0, y_{\!_f}, z_{\!_f})$$ and $$z_{\!_f}, z_{\!_f} \ne 0$$, then the coordinates of the newly created defect(s) is placed at a random $$(x_n)$$ with $$y_n = y_f, z_n = z_f$$, that is, at $$(x_n, y_n = y_{\!_f}, z_n = z_{\!_f})$$.
• If the coordinates of a fake defect are $$(x_{\!_f}, y_{\!_f}, z_{\!_f})$$ and $$x_{\!_f}, y_{\!_f}, z_{\!_f} \ne 0$$, then the newly created defect is placed at the same location as the parent fake defect.

## Reaction Event DB@

• Reaction event on line №. 6, specifies the type and size of the newly created defect
• In this particular example, the reaction event specifies the creation of single-interstitial He atom
• Since the $$(x, y)=(0, 0)$$ while $$z \ne 0$$, newly created defects are placed in the same layer as the parent fake defect but at a random $$(x, y)$$ location
This reaction DB includes Depth dependent TM and TM+PD reactions
TypeID:     0     1   2    3    4
Dfct Type:  Vac. SIA  He  HeV  HeI
# hash symbol marks the end of comment section
55
f    1    1    1    0.1    0.1            1    2    1    2    4    1
c    1    1    1    0    0                1    2    1    0    3    a
c    1    1    1    1    1                1    2    1    1    3    a
c    1    1    1    2    2                1    3    1    2    3    a    4    a
c    1    1    1    3    3                1    4    1    3    3    a    4    a    5    0


## Limitations@

• The approach of using fake defect types is not designed to insert an MD1 generated cascade.

Note

• This page is a work in progress.

## References@

1. Hammond K D and Wirth B D 2014 J. Appl. Phys. 116 143301
2. Ferroni F, Hammond K D and Wirth B D 2015 J. Nucl. Mater. 458 419
Last updated on Oct 18, 2021, 8:41 PM(PST)

1. Molecular Dynamics

Back to top