Accuracy of non-self consistent current calculation

[Hassan]

Hi,

I'd like to know how accurate a non-self consistent current calculation is through the TransmissionSpectrum object?

Reading this page: http://www.quantumwise.com/documents/tutorials/latest/GrapheneDevice/index.html/chap.further.html

It seems like it's fairly accurate over a certain voltage range (-1, 0.6) V, but drops off rapidly after 0.6. What is the reason for this?

I'd like to know if my thinking here is correct, in order to speed up my current calculations.

Say I'd like to do an accurate Gate Bias vs. Current curve over (-3, 3) V, I would do self consistent calculations for 13 points (-+3, -+2.5, -+2, -+1.5, -+1, +-0.5, 0) V, and then do non-self consistent calculations around each of the self consistent bias points (e.g. for self consistent voltage -2.5, I'd do -2.75 to -2.25 with a step size of 0.01 Volts to get a finer curve.

Does this seem like a good idea?

Thanks for your help.

[Hassan]

Anyone?

[Anders Blom]

You are mixing up non-selfconsistent a linear response here a bit. The calculations in the tutorial are selfconsistent, else you can't get any effect of the gate whatsoever. But the zero bias transmission spectrum is assumed to hold for finite bias too, and that's an approximation that naturally gets worse with increasing bias. How bad is extremely system-dependent, but in general the transmission spectrum is really quite bias-dependent, which can be seen e.g. in the plots in Fig. 4 of Appl. Phys. Lett. 101, 073104 (2012).

You could however do a trick of the nature you mention, to interpolate between bias points using a local linear response expansion, to get a finer curve.