Messages

16

General Questions and Answers / Re: CNTFET using doped electrodes

« on: March 10, 2014, 19:15 »

Thank you for your reply. This definitely helps.

Can you give a short explanation, why multipole boundaries are not suitable for devices (only perpendicular to the device of course)?

17

General Questions and Answers / Re: CNTFET using doped electrodes

« on: March 10, 2014, 17:32 »

No answer here?

18

General Questions and Answers / CNTFET using doped electrodes

« on: February 24, 2014, 14:26 »

Hello everyone,

I'm trying to simulate a cylindrical gated CNTFET using ATK 12.8.2. The system is based on a (7,0) CNT, where I dope the electrodes using the "charge" keyword (each electrode has two unit cells of (7,0) CNT - 56 atoms - and the charge was set to "-0.5").
The gate is a spatial region and no dielectric region is inserted.
Extended Hueckel is the chosen method.

I have a question about the most suitable choice for the boundary conditions:
According to the tutorials and previous discussion (http://quantumwise.com/forum/index.php?topic=1597.0#.UwtBlduVvRY), Neumann boundaries are most suitable for studying the gate influence.
However, multipole boundaries are suggested for charged molecules.
I'm now wondering if I could use multipole boundaries for the transistor as well (as I have some kind of charged molecules as electrodes).

When I create a script using VNL to simulate the CNTFET, I cannot access the Multipole option. But when I directly edit the python script and change "NeumannBoundaryCondition" to "MultipoleBoundaryCondition", the job starts and ends successfully. Is there a reason why Multipole boundaries should not be used for a device calculation (e.g. a CNTFET)?