How to get the correct color scale for PLDOS?

[dmicje12]

Hello everyone!
I want to use PLDOS to know the band bending or barrier height
and I want to measure it directly on the PLDOS graph as shown in the attached picture.
But I found that as long as I change the color scale, the black area (band gap area) on the graph will expand or shrink, which means that the band bending or barrier height will also change. So is there a correct color scale that allows me to correctly judge the band bending?
If so, how can I get the correct color scale?
I can't find any relevant tutorials
Or PLDOS cannot determine the actual value of the component's band bending or barrier, and I need to calculate other physical quantities to make a judgment?

Thank you everyone!

[Anders Blom]

Yes, this can be a bit tricky since we interpret the band gap as the region where the DOS is zero, or very small. But it typically doesn't go to exactly zero in a numerical calculations, as you can very clearly see this in a log plot.

So there is no "correct" colorscale, it depends on the magnitude of the data and what you consider small enough to be "almost zero DOS".

Your final point is very apt. It can be hard to obtain (or even define) the exact value of the barrier from just this plot, but when you compute other quantities like current, it doesn't matter of course. When analyzing the plot, the key is to keep the coloring consistent when you compare different results, so that you have a consistent way to computing changes in the barrier height etc.

[dmicje12]

Thank you very much for your reply!
I have a few questions to ask
1.
Is it reasonable that the DOS near the edge of the valence band in the attached picture is discretely distributed?
Because I calculated that several structures have this phenomenon.
2.
I still want to know how high the barrier near the interface is.
The way I found the interface barrier in the tutorial is to use Arrhenius-like plot.
https://docs.quantumatk.com/casestudies/ag_si_interface/ag_si_interface.html
Is this method applicable to field effect transistors?
There is also a mention of the Hartree difference potential method in the link.
I would like to ask if the Hartree difference potential method is still applicable when gate bias is applied to the component?
If none of the above methods are used, are there any other methods?

Thank you so much!