QuantumATK Forum
QuantumATK => General Questions and Answers => Topic started by: Black Metal on July 27, 2014, 14:00
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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
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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.
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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
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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.
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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
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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.
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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
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Based on this Topic :
http://quantumwise.com/forum/index.php?topic=1052.0#.U95Tnr_wnj4
http://www.upload7.ir/imgs/2014-08/92265838961736186181.jpg
http://www.upload7.ir/imgs/2014-08/93203916252802981644.jpg
http://www.upload7.ir/imgs/2014-08/40427145360407554157.jpg
http://www.upload7.ir/imgs/2014-08/61577216854170155155.jpg
for created and Simulation [100] Si Nanowire (1.5X1.5 nm^2 cross-sectional area), I have done the following steps:
for created [100] Si Nanowire :
http://upload7.ir/imgs/2014-08/64394798068228741408.jpg
http://upload7.ir/imgs/2014-08/41156585695590955640.jpg
http://upload7.ir/imgs/2014-08/44296824178491580621.jpg
for passivated [100] Si Nanowire :
http://www.upload7.ir/imgs/2014-08/29105611932879888547.jpg
http://www.upload7.ir/imgs/2014-08/14588447352801611893.jpg
Lattice Parameters :
http://www.upload7.ir/imgs/2014-08/67961499768988867807.jpg
for Calculator Eg and effective mass to [100] Si Nanowire :
http://www.upload7.ir/imgs/2014-08/66775900918855671719.jpg
http://www.upload7.ir/imgs/2014-08/48782454675948906868.jpg
http://www.upload7.ir/imgs/2014-08/16368757109887140695.jpg
http://www.upload7.ir/imgs/2014-08/17943543256305237287.jpg
http://www.upload7.ir/imgs/2014-08/12171100825222868728.jpg
http://www.upload7.ir/imgs/2014-08/40572682809530760451.jpg
http://www.upload7.ir/imgs/2014-08/52517970968663579648.jpg
http://www.upload7.ir/imgs/2014-08/61405080939064703739.jpg
Results :
http://www.upload7.ir/imgs/2014-08/28941439725807153255.jpg
http://www.upload7.ir/imgs/2014-08/83147039131564889848.jpg
http://www.upload7.ir/imgs/2014-08/05488740744683770722.jpg
http://www.upload7.ir/imgs/2014-08/74994397913592353034.jpg
Eg=1.981, K[0,0,0]
for apply Strain to [100] Silicon Nanowire (Uniaxial Tensile Strain 1%): 5.4306--->5.5306
http://www.upload7.ir/imgs/2014-08/77792845580931293334.jpg
I have done the correct steps ...!!!???, How I can calculated effective mass (transport and subband) to [100] SiNW ...!!!???
Please help me :'(
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we have a new tutorial for this which will be posted within the next 1-2 weeks
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Thank you very much, but is it possible that the tutorial a little earlier this ...!!!???, My time is very limited ...!!!??? :'(
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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 ...!!!???
???
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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 ...!!!???
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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.
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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 ... :(
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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.
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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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1. please refer to the discussion in the following thread:
http://quantumwise.com/forum/index.php?topic=2026.0
2. the reasons for your results different from those reported in literature could be quite complicated, e.g., even the thickness of nanowires are the same as those in literature, the atomic positions and the computational setup (e.g., some key parameters in the computational method) may be different. To reproduce the results in literature, it usually needs more patients and carefulness. Sometimes it is necessary to contact the authors of the original sources in order to figure out the exact reasons, because more or less details of computational setup were hidden in paper.
3. As said last several posts, you cannot apply biaxial strain to an individual nanowire. The manner illustrated in your image is not applicable because the lattice constant A includes the vacuum thickness. The change in the lattice constant A is just to alter the vacuum thickness.
4. Yes, the effective mass of a nanowire can obtained by following that tutorial.
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Thank you for Reply to my question But two Questions ...!!!
1. How I can build a circular cross section ...!!!???
2. Can I use from method Created Silicon Nanowire for created Gaas Nanowire ...!!!???
Thanks
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1. The nanowire with circular cross section could be built by choosing proper values for the surface energies [100], [110], [111]. Please try different values by yourself to find out the proper ones. Please don't ask the exact values.
2. Using the similar steps you of course can build the GaAs nanowire from cubic bulk GaAs.
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OK, Thanks ... ;D
I've done all the steps are similar for created Gaas Nanowire but several questions ...!!!???
1. passivated [100] Gaas Nanowire (1X1 nm^2 cross-sectional area) Was performed as follows, do you think it is correct ...!!!???
http://upload7.ir/imgs/2014-08/51853168370542971296.jpg
http://upload7.ir/imgs/2014-08/07580765174953827058.jpg
2. I've used DFT (GGA) method for Calculation Eg but The value is not visible ...!!!???
http://upload7.ir/imgs/2014-08/99279190190848496906.jpg
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OK, Thanks ... ;D
I've done all the steps are similar for created Gaas Nanowire but several questions ...!!!???
1. passivated [100] Gaas Nanowire (1X1 nm^2 cross-sectional area) Was performed as follows, do you think it is correct ...!!!???
I don't understand why you ask such question so many times. Once you understand the basic procedure (and steps), you can judge it by yourself.
Maybe the calculated band gap is too small. You can zoom in the plot to show the energy range around 0.0 eV (e.g. -0.5 eV to 0.5 eV). In such small energy range, you may see the band gap. If not, you had better calculate the bulk material using the same key parameters ( pseudopotential, exchange-correlation functional, and mesh cutoff) to check the band gap of bulk material at first. And so you should ensure that all surface atoms are passiviated by hydrogen and that the structure is optimized.
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OK, Thanks ... ;D
I've done all the steps are similar for created Gaas Nanowire but several questions ...!!!???
1. passivated [100] Gaas Nanowire (1X1 nm^2 cross-sectional area) Was performed as follows, do you think it is correct ...!!!???
I don't understand why you ask such question so many times. Once you understand the basic procedure (and steps), you can judge it by yourself.
Maybe the calculated band gap is too small. You can zoom in the plot to show the energy range around 0.0 eV (e.g. -0.5 eV to 0.5 eV). In such small energy range, you may see the band gap. If not, you had better calculate the bulk material using the same key parameters ( pseudopotential, exchange-correlation functional, and mesh cutoff) to check the band gap of bulk material at first. And so you should ensure that all surface atoms are passiviated by hydrogen and that the structure is optimized.
My basic problem It is, I can not apply passiviated by hydrogen on gallium atoms, How I can passiviated the gallium atoms ...!!!???
http://upload7.ir/imgs/2014-08/00526715511832186959.jpg
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I'm trying to created a square cross sectional area for [111]Silicon Nanowire by Changes in values surface energies but still I could not do this work, Is it possible to do this ...!!!???
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There is a new way to passivate e.g. III-V structure coming out in VNL 2014, and there is an accompanying tutorial for it, which will come online next week.