QuantumATK Forum

QuantumATK => General Questions and Answers => Topic started by: bfazi on June 14, 2015, 17:11

Title: Graphene nanoribbon device with Au or Ag electrodes
Post by: bfazi on June 14, 2015, 17:11

Hi all

Is it possible to create a graphene nanoribbon device with Au or Ag electrodes in ATK? If possible, how?

Thanks

Title: Re: Graphene nanoribbon device with Au or Ag electrodes
Post by: Jess Wellendorff on June 15, 2015, 09:33

That is most certainly possible.

There is probably gonna be a few steps in the procedure:
1) build the nanoribbon (perhaps also relax it),
2) build the electrodes (perhaps using relaxed unit cells),
3) create the device (electrodes + nanoribbon).

Please have a look a these two tutorials for inspiration:
http://quantumwise.com/publications/tutorials/item/103-building-a-molecular-junction-au-dtb-au
http://quantumwise.com/documents/tutorials/latest/GrapheneDevice/index.html

Title: Re: Graphene nanoribbon device with Au or Ag electrodes
Post by: Jess Wellendorff on June 24, 2015, 14:42

Well, the figure in the reference you provided is quite simplistic, so you should take care when trying to reproduce results. For example, there is no indication of how the device should be separated into electrodes and a quantum transport region. The VNL device configuration is therefore not supposed to look exactly like the illustration!

If you for example want to reproduce the bandstructure calculations in Fig 2, you would indeed set up a device configuration just like the one you already made. Remember how a device is defined: a finite transport region (finite along the transport direction) sandwiched between two infinite leads (considered infinite, or bulk-like, along the transport region). It therefore makes no sense to have a gate or dielectric in the electrode regions (indeed, this is simply not possible in VNL), because gates and dielectrics are by definition part of the quantum transport region.