device bandstructure

[xiaolight]

The professor asks me to plot the band structure of the device (Fecl2-MoS2-FeCl2) and asks me to make the vacuum level uniform.I am a little bit confused that what does 'making the vacuum level uniform' mean.Does it mean that I have to adjust the vacuum of the FeCl2 region and MoS2 region because of the different work function? If so, how can I do that? I have also done the effective potential calculation. Does it help?  The configuration of the device and the effective potential are posted below.

[Jess Wellendorff]

Sounds like you need to ask your professor exactly what he means.

[Parveen]

Is it possible to plot band-structure diagram for devices with the help of VNL-ATK? I'm using 2014.3 version and didn't find any analyser for band-structure.

[Petr Khomyakov]

Strictly-speaking, the band structure is uniquely defined for a perfectly-periodic crystal structure only; this is why there is no band structure analyzer for device configuration.

I guess the band diagram you are referring to is that given by the Hartree Difference Potential (HDP) as discussed in the following tutorial http://docs.quantumwise.com/casestudies/ag_si_interface/ag_si_interface.html. So, you will need to compute the HDP for your device structure, and the HDP curve can then be considered as a visualization for how the conduction (valence) band minimum (maximum) changes across the device.

In the vacuum, the HDP goes to a constant that defines the vacuum level, and you can calculate the Fermi energy with respect to this level.