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General Questions and Answers / Re: electrode effects on resistance
« on: July 31, 2018, 15:57 »
They are from same materials but the electrodes have some dopant atoms.
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General Questions and Answers / Re: electrode effects on resistance
« on: July 31, 2018, 11:35 »
I think I find the answer. the resistance comes from the coupling between the electrodes and the scattering region so it depends to both contact and conductors, is it right?
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General Questions and Answers / electrode effects on resistance
« on: July 31, 2018, 10:54 »
Dear experts,
Assume that we have a linear I-V characteristic, so we can consider resistance as the slope of the I-V diagram equal to R=V/I .
Now, this resistance shows the resistance of just the scattering region? or it is the resistance of whole the device?
As the current passes through the scattering region, and the applied bias is over the scattering region, I think it should be device resistance, but I know that if we change the electrodes, the I-V curve could change which leads to a new resistance value. This shows the resistance also depends on the electrodes.
Could anyone explain this issue to me?
I really appreciate your help in advance.
Nazi
Assume that we have a linear I-V characteristic, so we can consider resistance as the slope of the I-V diagram equal to R=V/I .
Now, this resistance shows the resistance of just the scattering region? or it is the resistance of whole the device?
As the current passes through the scattering region, and the applied bias is over the scattering region, I think it should be device resistance, but I know that if we change the electrodes, the I-V curve could change which leads to a new resistance value. This shows the resistance also depends on the electrodes.
Could anyone explain this issue to me?
I really appreciate your help in advance.
Nazi
4
General Questions and Answers / question on strained electrode
« on: June 25, 2018, 15:08 »
Dear experts,
Considering electronic properties of the system under strain is an important topic in physics and technology.
Now my question is that is it physically acceptable to apply strain on whole the device including the electrode parts?
or we are just allowed to consider the strain effect on the scattering region?
I really appreciate your answers.
Regards,
Nazi
Considering electronic properties of the system under strain is an important topic in physics and technology.
Now my question is that is it physically acceptable to apply strain on whole the device including the electrode parts?
or we are just allowed to consider the strain effect on the scattering region?
I really appreciate your answers.
Regards,
Nazi
5
General Questions and Answers / Re: transport in pure materials
« on: May 23, 2018, 12:41 »
Dear Petr,
I know the e-ph interactions could be important in the transport results; however, I ignore this interaction.
I would like to study transport in a pure system without any dopant in the central region; the leads are metal but the central region is pure without any defects.
The simulation of such a system is not physically true? why?
From your response, I think we are forced to consider some scattering centers in the system.
Thank you.
Nazi
I know the e-ph interactions could be important in the transport results; however, I ignore this interaction.
I would like to study transport in a pure system without any dopant in the central region; the leads are metal but the central region is pure without any defects.
The simulation of such a system is not physically true? why?
From your response, I think we are forced to consider some scattering centers in the system.
Thank you.
Nazi
6
General Questions and Answers / Re: transport in pure materials
« on: May 23, 2018, 11:10 »
Thank you Petr for your useful guides.
I am doing my homework but the results are sometimes strange for me and I need help to understand.
Again thank you very much for your help.
Regards,
Nazi
I am doing my homework but the results are sometimes strange for me and I need help to understand.
Again thank you very much for your help.
Regards,
Nazi
7
General Questions and Answers / Re: transport in pure materials
« on: May 23, 2018, 08:23 »
Dear Petr,
I have used the metallic electrodes in my device; however, the central scattering region is pure 2D phosphorene without any defects.
But the calculated current shows that it is again length dependent. by increasing the length of scattering region the current intensity decreases.
As there is no scatterer in the central region, I don't understand this behavior.
Would you please explain it to me?
I really appreciate your help in advance.
Regards,
Nazi
I have used the metallic electrodes in my device; however, the central scattering region is pure 2D phosphorene without any defects.
But the calculated current shows that it is again length dependent. by increasing the length of scattering region the current intensity decreases.
As there is no scatterer in the central region, I don't understand this behavior.
Would you please explain it to me?
I really appreciate your help in advance.
Regards,
Nazi
8
General Questions and Answers / Re: transport in pure materials
« on: May 22, 2018, 12:26 »
Dear Petr,
As I explain in my last post, as there is no scatterer in the central region of my device, I can't understand the dependence of current intensity to the length of the central region.
Regards to your answer, this problem arises by the non-metallic electrodes?
If I have metallic electrodes, the current intensity passes true the pure scattering region does not change by changing the length of scattering region?
I really appreciate your help.
Regards,
Nazi
As I explain in my last post, as there is no scatterer in the central region of my device, I can't understand the dependence of current intensity to the length of the central region.
Regards to your answer, this problem arises by the non-metallic electrodes?
If I have metallic electrodes, the current intensity passes true the pure scattering region does not change by changing the length of scattering region?
I really appreciate your help.
Regards,
Nazi
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General Questions and Answers / Re: transport in pure materials
« on: May 21, 2018, 08:20 »
Dear Petr,
Thank you for your response.
So what shall we do to study the transport properties of a pristine system under bias voltage?
Maybe just by considering the zero-bias transmission; but in this regards, we cannot find for example NDR characteristic in the IV curve of a system.
Thanks in advance for your answer.
Nazi
Thank you for your response.
So what shall we do to study the transport properties of a pristine system under bias voltage?
Maybe just by considering the zero-bias transmission; but in this regards, we cannot find for example NDR characteristic in the IV curve of a system.
Thanks in advance for your answer.
Nazi
10
General Questions and Answers / transport in pure materials
« on: May 20, 2018, 17:01 »
Dear experts,
In the Datta's book say that:
"We can easily see that the resistance G-1 is associated with the interfaces and not with the conductor itself"
But my results show that calculating the current under bias voltage in a pure 2D system depends on the length of the scattering region. Also, this dependent is not linear, for example, under bias voltage 2V the calculated current in the larger system is 1/3 of the current of the smaller system but under bias voltage 3 this ratio could be different. The current intensity is in the order of several micro Amper.
As the system is pure and there is no scatterer in the system, what is the reason of this behavior?
Second question: is the implemented method in quantumwise valid for such a study (calculating current under bias-voltage in a 2D system)?
I really appreciate your help in advance.
Nazi
In the Datta's book say that:
"We can easily see that the resistance G-1 is associated with the interfaces and not with the conductor itself"
But my results show that calculating the current under bias voltage in a pure 2D system depends on the length of the scattering region. Also, this dependent is not linear, for example, under bias voltage 2V the calculated current in the larger system is 1/3 of the current of the smaller system but under bias voltage 3 this ratio could be different. The current intensity is in the order of several micro Amper.
As the system is pure and there is no scatterer in the system, what is the reason of this behavior?
Second question: is the implemented method in quantumwise valid for such a study (calculating current under bias-voltage in a 2D system)?
I really appreciate your help in advance.
Nazi
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General Questions and Answers / Re: accuracy of current
« on: May 18, 2018, 13:07 »
Dear Petr,
Thank you very much for your guides. Just one question to be sure that I got your meaning correctly.
The calculated currents using the transmission in zero bias and finite bias are different. You believe that for such a system the calculated current using the linear response (zero bias) is correct and the other one does not make sense. Am I right?
Additionally, if I turn to my first question, if we sure about the cutoff parameters, can we trust the small current values in the order of 1E-16A?
Thank you very much for your guides. Just one question to be sure that I got your meaning correctly.
The calculated currents using the transmission in zero bias and finite bias are different. You believe that for such a system the calculated current using the linear response (zero bias) is correct and the other one does not make sense. Am I right?
Additionally, if I turn to my first question, if we sure about the cutoff parameters, can we trust the small current values in the order of 1E-16A?
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General Questions and Answers / Re: accuracy of current
« on: May 18, 2018, 11:25 »
Dear Petr,
I am a little confused
the potential profile across the central region depends on the central region length,
Yes, the resistance and conductance depend on the length, what is wrong with this?
Also as the system is 2D, the transport regime is not ballistic in the terms of quantized conductance and transmission spectrum.
I am a little confused
the potential profile across the central region depends on the central region length,
Yes, the resistance and conductance depend on the length, what is wrong with this?
Also as the system is 2D, the transport regime is not ballistic in the terms of quantized conductance and transmission spectrum.
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General Questions and Answers / Re: accuracy of current
« on: May 18, 2018, 09:37 »
The bias voltage is ~ 1V.
My transmission spectrum under bias and in equilibrium (zero bias) is completely different.
Also in the transport book of Datta it comes that linear response is valid just when the bias voltage is smaller than the thermal energy and band broadening. These conditions were not satisfied in nanostructures. Am I right?
My transmission spectrum under bias and in equilibrium (zero bias) is completely different.
Also in the transport book of Datta it comes that linear response is valid just when the bias voltage is smaller than the thermal energy and band broadening. These conditions were not satisfied in nanostructures. Am I right?
14
General Questions and Answers / Re: accuracy of current
« on: May 17, 2018, 16:30 »
Dear Petr,
Thank you for your response. The unit of the current is Amper, my system is 2D phosphorene.
Thank you.
Thank you for your response. The unit of the current is Amper, my system is 2D phosphorene.
Thank you.
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General Questions and Answers / accuracy of current
« on: May 17, 2018, 07:45 »
Dear experts,
The calculated current in my system under an applied bias voltage is in order of 1E-16.
I am sure about different convergence parameters like cutoff energy and k-points.
As the exact order of current is important for me, can I trust such a small current value?
I really appreciate your response in advance.
Best regards,
Nazi
The calculated current in my system under an applied bias voltage is in order of 1E-16.
I am sure about different convergence parameters like cutoff energy and k-points.
As the exact order of current is important for me, can I trust such a small current value?
I really appreciate your response in advance.
Best regards,
Nazi
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