Can someone give me ideas on how to make a basic FDSOI device?

[yang su]

Hi everyone,

I am a PhD student and I am pretty new to this software. My research involves mainly device simulations and I wish I can start with the most basic device like FDSOIs. I have gone through the builder tutorial but none of them talks about devices so I am totally puzzled. Can you please give me some ideas on how to make the device or are there any tutorials regarding that? I am pretty new and so no background of me can be expected. I am currently using the GUI mode in windows now. Thank you very much.

[mads.engelund]

The builder tutorials gives a good impression of what can be built in our software.
http://www.quantumwise.com/publications/tutorials/builder/

Full device simulations like the one you are talking about, cannot realisticly be calculated in ATK due to the large number of atoms.
Interface resistance, tunneling across layers, small model devices, are things we can do

[yang su]

Thank you very much but I am building a 2-D but 3 terminal device. Is that possible if only hundreds of  atoms are involved? If so, can I get some information about making channel and contact interface and how can I specify the 3 terminals I need? Thank you.

[mads.engelund]

You are right, the number of atoms is no problem in that case.
But unfortunately ATK can't do 3-terminal devices yet. And the two terminals must be straight ahead of each other.

It is, however, possible to add gates to a two-terminal device. You can add continuum regions at a fixed potential. These can be added in using the Builder > Michellaneous > Spatial Regions.

[yang su]

Thank you very much. Actually the major concern of my device is just a single channel MoS2 layer in the central region. Is that possible if I just specify a MoS2 layer and specify the two source and drain terminals as bulk gold since only the electric parameters are what I care. I also want to add a oxide layer on the top of my channel MoS2 layer. Since I want to save some simulation efforts and only some parameters like dielectric constant of the oxide layer are important. Can I just name that layer a "bulk" layer instead of showing and simulating all the atoms? I wish I can do atomic level simulation just in the central MoS2 layer. Thank you very much.

[Anders Blom]

Yes, you can describe the dielectrica as just a continuum dielectric region, and the channel atomistically, like we do in the Graphene Junction tutorial (http://quantumwise.com/documents/tutorials/latest/GrapheneDevice/index.html/).

Also see http://dx.doi.org/10.1038/am.2012.10 for some inspiration and ideas!

[yang su]

Thank you and I made it successfully. But when I tried to make the channel I was asked to specify the size in all three dimensions of the channel layer by atk. The only concern of mine is just the channel direction(Z)
and the vertical direction(X). Can we make the assumption in the software that the size of the Y direction is infinite by using periodic boundary conditions? Thank you.

[kstokbro]

yes this is correct, you can make one of the directions periodic, and thereby simulate an infinite system in that direction.
Remember to perform k-point sampling in that direction when setting up a calculator.

[yang su]

Thank you for your reply and how can I do that in atk? Should I just specify that a direction is infinite and periodic or do I need to do that in the caculator? What operation should I perform in the builder? Thank you.

[yang su]

And by the way. If I wanna specify my contacts as gold. Should I just use spacial region in the builder of I need to actually add gold atoms at the contact area? Thank you so much.