Author Topic: Si Nanowire (Read 15403 times)

Black Metal · « **on:** July 27, 2014, 14:00 »

Hi, Is there a method for apply the dimensions of the cross section Based nm ...!!!???
For example :
[100] Silicon Nanowire (square cross section 1.5 × 1.5 nm^2)

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My next question, Is there a method for exhibit (Eg OR effective masses) as function of Changes dimensions of the cross section OR apply Strain ...!!!???

http://img.majidonline.com/pic/309058/01.png
http://img.majidonline.com/pic/309059/02.png
http://img.majidonline.com/pic/309060/03.png

References:
http://ieeexplore.ieee.org/xpl/articleDetails.jsp?arnumber=6178787
http://www.sciencedirect.com/science/article/pii/S0038110112003516

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Thanks

zh · « **Reply #1 on:** July 28, 2014, 12:04 »

The change of dimension of the cross section of a nanowire doesn't correspond to the applied biaxial strain, and it just means the change of thickness of nanowire.

Please refer to the following paper to understand the method of Constant pressure molecular dynamics simulations for finite systems (nano-system):
http://pubs.rsc.org/en/Content/ArticleLanding/2010/CP/c004053c

The two papers mentioned by show some results for the biaxial strain of Silicon nanowires. They may be problematic. Please refer to the original ones:
Ki-Ha Hong, Jongseob Kim , Sung-Hoon Lee and Jai Kwang Shin, Strain-Driven Electronic Band Structure Modulation of Si Nanowires, Nano Lett., 2008, 8 (5), pp 1335–1340
http://pubs.acs.org/doi/abs/10.1021/nl0734140

Tadashi Maegawa, Tsuneki Yamauchi, Takeshi Hara, Strain Effects on Electronic Bandstructures in Nanoscaled Silicon: From Bulk to Nanowire, IEEE TRANSACTIONS ON ELECTRON DEVICES, VOL. 56, NO. 4, APRIL 2009, 553-559
http://ieeexplore.ieee.org/stamp/stamp.jsp?arnumber=4796299

Actually in these two original papers the authors applied the biaxial strain to the silicon films (i.e., silicon slab) not the silicon nanowire.

Black Metal · « **Reply #2 on:** July 28, 2014, 17:30 »

Thank you for reply to my question But My basic question is related to dimensions of the cross section To Silicon Nanowire for Simulation By ATK, Is there a method for apply dimensions Based on nm (Nano Meter) ...!!!???
My next question related to exhibition Schematic By ATK, Is there a method for exhibit Changes Eg as function of Changes dimensions of the cross section Based on graphical figure ...!!!???
For example :
http://img.majidonline.com/pic/309058/01.png
exhibition graphical Changes Eg as function of Changes dimensions of the cross section (Axis X = Changes dimensions of the cross section , Axis Y = Changes Eg)
Thanks

zh · « **Reply #3 on:** July 29, 2014, 03:43 »

Since 1nm= 10 Angstrom, you can apply dimensions based on unit of nm by converting the unit of length.
If the computational resource available to you is sufficient enough, you can do the simulations of much large dimension of silicon nanowire as you want.

Once you have done a serial of calculations for different size (thickness, or area of cross section) of nanowires, you can easily plot the calculated properties such as Eg as the function of the size of nanowires. This kind of representation (or plot) is independent of the ATK. Of course, you draw such plot by using the matplotlib as embedded in ATK or other visualization softwares such as gnuplot and xmgrace.

Black Metal · « **Reply #4 on:** July 29, 2014, 17:31 »

For study the effects apply Strain and study the effects Changes Thickness, I created Structure Silicon Nanowire by This Tutorial (Of course to page 11)

http://quantumwise.com/documents/tutorials/latest/NanowireDevice/NanowireDevice.pdf
http://quantumwise.com/documents/tutorials/latest/NanowireDevice/index.html/

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A Question, Is it this structure is correct...!!!???

http://upload7.ir/imgs/2014-07/13180241540132818159.jpg
http://upload7.ir/imgs/2014-07/83418215152143289239.jpg
http://upload7.ir/imgs/2014-07/69019438953797660762.jpg
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If correct structure, My next question relates to the definition dimensions of Cross section, Is it possible to change the distance between the atoms for create cross sectional 1 × 1 nm^2
http://www.upload7.ir/imgs/2014-07/89183462491135673753.jpg

The amount of default ATK to Tutorial is 170 × 170 nm^2
http://www.upload7.ir/imgs/2014-07/78322766137336276152.jpg
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My next question, How can calculation Eg of silicon nanowire By metod tight binding ...!!!???

Thanks

zh · « **Reply #5 on:** July 31, 2014, 02:16 »

It may be roughly correct depending on your purpose. But it can't be used for study the band structure because the structure of your built nanowire doesn't have periodicity along the wire axis. The silicon atoms at the top and bottom cross plane were hydrogenated.

You can use the "Nanowire" tool in "Builder" to create a silicon wire. The dimension of cross area of silicon can be controlled by the "cluster radius" in that tool.
It is very obvious that the dimension of cross area can't be tuned by changing the distance between atoms.

For your last question, please refer to the manual to learn how to do the band structure calculations.

Black Metal · « **Reply #6 on:** July 31, 2014, 13:14 »

Thank you for Reply to my question But Several Questions ...!!!???

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How can to this method specify the dimensions of SiNW ...!!!???
For example, cross sectional:
1 × 1 nm^2 , 2 × 2 nm^2 , 3 × 3 nm^2 , 4 × 4 nm^2 or ...

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How can apply strain (tensile , compressive) to in method ...!!!???
For example, apply tensile strain : 1% or 0.5%

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for study Changes Eg as function of Changes dimensions of the cross section to SiNW, Necessarily use from tight binding method ...!!!???

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Can we use from This Tutorial for calculated effective mass (transport and subband) to SiNW...!!!???
http://quantumwise.com/publications/tutorials/mini-tutorials/135

Black Metal · « **Reply #7 on:** August 3, 2014, 18:02 »

kstokbro · « **Reply #8 on:** August 4, 2014, 07:44 »

we have a new tutorial for this which will be posted within the next 1-2 weeks

Black Metal · « **Reply #9 on:** August 4, 2014, 21:27 »

Thank you very much, but is it possible that the tutorial a little earlier this ...!!!???, My time is very limited ...!!!???

Black Metal · « **Reply #10 on:** August 6, 2014, 20:44 »

How can apply very low distance between atoms (for example Si-Si = 0.24 nm) ...!!!???
Is there any way for zoom in on very low distance between atoms ...!!!???

zh · « **Reply #11 on:** August 7, 2014, 02:17 »

Quote from: Black Metal on August 6, 2014, 20:44

How can apply very low distance between atoms (for example Si-Si = 0.24 nm) ...!!!???
Is there any way for zoom in on very low distance between atoms ...!!!???

Sometimes it is difficult to capture the exact points in your question because of the grammar.

The distances between atoms in a system you have built are coherent, that is to say, they depend on how you build a system. For example, if you build a Si nanowire with a length longer than 0.24 nm, you can find some of atoms being equal to or larger than 0.24nm, otherwise, in a Si nanowire with a length shorter than 0.24nm you cannot find any two atoms with distance larger 0.24nm.

For the appearance of two atoms with long distance on the screen during the zooming in process, it somehow depends on the screen size of your computer. For a smaller screen size, such two atoms could be out of the screen when they are zoomed in.

Black Metal · « **Reply #12 on:** August 8, 2014, 19:54 »

Quote from: zh on August 7, 2014, 02:17

Quote from: Black Metal on August 6, 2014, 20:44
How can apply very low distance between atoms (for example Si-Si = 0.24 nm) ...!!!???
Is there any way for zoom in on very low distance between atoms ...!!!???

Sometimes it is difficult to capture the exact points in your question because of the grammar.

The distances between atoms in a system you have built are coherent, that is to say, they depend on how you build a system. For example, if you build a Si nanowire with a length longer than 0.24 nm, you can find some of atoms being equal to or larger than 0.24nm, otherwise, in a Si nanowire with a length shorter than 0.24nm you cannot find any two atoms with distance larger 0.24nm.

For the appearance of two atoms with long distance on the screen during the zooming in process, it somehow depends on the screen size of your computer. For a smaller screen size, such two atoms could be out of the screen when they are zoomed in.

I'm reading this article and done all settings are according to the article, just I could not adjust the distance between atoms ...

http://ieeexplore.ieee.org/xpl/articleDetails.jsp?arnumber=6178787

http://upload7.ir/imgs/2014-08/27814446166383853560.jpg

Do you think I've done it correctly simulation of SiNW ...!!!???, I am impatiently waiting for your answer ...

zh · « **Reply #13 on:** August 9, 2014, 10:13 »

It is quite unreasonable to adjust manually (e.g., manipulate the atoms by the mouse or by shifting their coordinates in the input file) the distance between atoms. Before calculating the electronic structures (e.g, band structure and effective mass) of a nanowire built from the tool, one has better do the geometry optimization for the positions of atoms for the unstrained and strained nanowires.

The steps in the basic procedure for your calculations seem OK.

Black Metal · « **Reply #14 on:** August 9, 2014, 19:13 »

Quote from: zh on August 9, 2014, 10:13

It is quite unreasonable to adjust manually (e.g., manipulate the atoms by the mouse or by shifting their coordinates in the input file) the distance between atoms. Before calculating the electronic structures (e.g, band structure and effective mass) of a nanowire built from the tool, one has better do the geometry optimization for the positions of atoms for the unstrained and strained nanowires.

The steps in the basic procedure for your calculations seem OK.

When I'm using the method Extended Huckel, This geometry optimization is disabled ...!!!
http://www.upload7.ir/imgs/2014-08/84806232974711050359.jpg

My next problem is that, the results that I got the results of different article ...!!!
Eg For:
1 nm ---> 2.514
2 nm ---> 1.825
3 nm ---> 1.532

But the results of article :
http://img.majidonline.com/pic/309058/01.png

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My next question, Can I use the following settings for apply biaxial strain ...!!!???
http://www.upload7.ir/imgs/2014-08/09143309982231980892.jpg

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My last question, How do I calculate the effective mass (transport and subband) to SiNW (Of course using the training)...!!!???
http://quantumwise.com/publications/tutorials/mini-tutorials/135

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Please, Can you help me ...!!!???, I am impatiently waiting for your answer ...

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Author Topic: Si Nanowire (Read 15403 times)

Black Metal

Si Nanowire

zh

Re: Si Nanowire

Black Metal

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zh

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Black Metal

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kstokbro

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zh

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Black Metal

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