Topics

1

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

2

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

3

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

4

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

5

General Questions and Answers / voltage drop behavior

« on: May 15, 2018, 08:16 »

Dear experts,

In many systems, the voltage drop across to the transport direction is not a linear ramp, and it has convex or concave shapes. My question is that what is the meaning of this behavior?

What is the main difference between two systems where the voltage of one of them drops linearly across the central scattering region, but the other one does not drop linearly?

Thank you very much in advance.
Nazi