Author Topic: About the gate electrode  (Read 2927 times)

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Offline Max

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About the gate electrode
« on: May 6, 2014, 10:13 »
Dear all,

Using ATK 2008.10, I studied the transport of a transition matel-doped Si structure contacted with Cu electrodes. A gate electrode is introduced in my system. I describe Vg in my manuscript like this (I use ATK 2008.10):

"Gate voltage is introduced by adding an external electro-static potential into the effective potential Veff[n](r) in the one-electron Kohn-Sham Hamiltonian."

However, the reviewer asked me to provide more about Vg, see below.

1. The author should describe what kind of external electro-static potentials added into the effective potential Veff(r) in the one-electron Kohn-Sham Hamiltonian as the gate voltage Vg.

2. The author should comment on the effects of gate electrodes on to the electronic structures and the spin dependent transport of the Si structure in the realistic system.


As for Point 1, I know "the electrostatic effect of the gate electrode is simulated by simply shifting the scattering region part of the Hamiltonian with the gate voltage (converted into an electrostatic potential energy)", and "only shift the diangonal terms H_ii, and all (selected) atoms were shifted by the same, fixed amount".

Here, I want to know the quantitative expression of this "fixed amount", is it -e*Vg ? or something else?

As for Point 2, would you please give me some suggestions? :)

Thank you!

Offline kstokbro

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Re: About the gate electrode
« Reply #1 on: May 7, 2014, 11:09 »
Hi Max,
We really do not support ATK 2008 anymore, however, I will make an exception and answer your mail.
1. Yes, this is correct
2. Difficult to answer, when we do not know your device structure. However, if you have a bulk system, the shift is applied inside the bulk of the device while in a realistic system the gate potential is placed outside the device and the field must penetrate inside the device.  In case there is no special screening at the surface of the device, this should be a realistic model, however, the device geometry will determine how the applied gate potential is related to the potential inside the device.

Offline Max

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Re: About the gate electrode
« Reply #2 on: May 12, 2014, 04:02 »
Dear kstokbro,

Thank you for your answer! It really helps me a lot!