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QuantumATK => General Questions and Answers => Topic started by: narin on October 13, 2015, 20:26

Title: IV curve of a doped GNR
Post by: narin on October 13, 2015, 20:26

Hello
I tried the simulation of a doped armchair GNR (N=10) and obtained its IV curve, I attached my script. I did the doping exactly the same direction as the silicon pn junction tutorial. However as you can see from the attached nc file (https://dropmefiles.com/lRHvy), IV curve is inversed. Could you please give an idea on why I got an inversed IV curve. Also, there are ripples in the non-conducting regime as you can see. Is it normal or should I fine adjuct any parameters? Thanks a lot. Regards.

Title: Re: IV curve of a doped GNR
Post by: Umberto Martinez on October 14, 2015, 13:58

Hi,
your script looks fine and your output as well.
just double check that all calculations at different biases are converged. I
To do so, check in your log file.

Otherwise, you are comparing a bulk silicon device with a graphene nanoribbon.
You do expect differences i the results :)

Maybe you just want to check the doping level.

Title: Re: IV curve of a doped GNR
Post by: Jess Wellendorff on October 14, 2015, 14:46

I cannot figure out which tutorial IV-curve you are comparing to, but to me your obtained IV-curve looks very nice and reasonable for a pn junction.

Title: Re: IV curve of a doped GNR
Post by: narin on October 14, 2015, 15:16

Hi

Thanks for your replies. I'm comparing the IV curve of the silicon pn junction tutorial http://quantumwise.com/publications/tutorials/item/828-silicon-p-n-junction and the IV curve given in that tutorial:

(http://s7.postimg.org/8fewhdee3/IV_Plot_SK.png) (http://postimage.org/)

My IV curve seems to have currents in the opposite way, in negative voltages the current flows but in the tutorial in positive voltage current flows, I'm using the same doping direction  as can be seen from my code and the tutorial.

And your first question: I checked the log file and the calculations have converged.

Thanks a lot.

Title: Re: IV curve of a doped GNR
Post by: Jess Wellendorff on October 15, 2015, 11:48

Right, then I guess the two cases are just so different (very different nanoscale devices) that the electronic transport properties are different. There is really nothing to suggest that you did the calculations wrong.

Title: Re: IV curve of a doped GNR
Post by: narin on October 15, 2015, 13:29

Hi,
Thanks for your help. Regards.