QuantumATK Forum

QuantumATK => General Questions and Answers => Topic started by: lknife on October 12, 2017, 16:00

Title: asking for the explanation of the IV curve
Post by: lknife on October 12, 2017, 16:00

Dear experts,

I am now studying the tutorial "Transport calculations with ATK", https://docs.quantumwise.com/tutorials/atk_transport_calculations/atk_transport_calculations.html.

I have a question about the IV curve in this tutorial: is there any explanation for the fluctuation of the dI/dV curve or the increased R at bias about 0.9V for this particular device, seen in the attached figure?  Where can I find such explanation from literature?

Thank you very much for your kind help!

Title: Re: asking for the explanation of the IV curve
Post by: Jess Wellendorff on October 13, 2017, 12:01

Negative differential conductance (NDC), where dI/dV becomes negative, is observed experimentally, and often actively looked for in device simulations. So there are lots of papers on NCD (or NRD, as it's also called). However, in this case it could also be a computational artifact (we did not check if the calculation converged well at the higher bias points). Also, from a more physical point of view, 1 Volt bias applied over a few nanometers is probably above the breakdown voltage anyway, so it might not be a physically realistic scenario.

Title: Re: asking for the explanation of the IV curve
Post by: lknife on October 18, 2017, 05:11

Thank you very much for your kind reply and information! If I have checked that the transmission spectrum under these biases are well converged, can I conclude that this NDC phenomenon in my simulation would be a physically realistic scenario?

Title: Re: asking for the explanation of the IV curve
Post by: Jess Wellendorff on October 18, 2017, 09:16

Depends on whether the device is physically stable at the IV point at which you find NDC.