Ohmic and shottky contact or how can I make different electrodes

[Ikgut]

Hi all,

Im new at forum. I read all tutorials from ATK but I dont find a answer. I want to build some structure with different elektrodes In/Au and Au. One is Schottky an another is ohmic contact. I thought to set workfunktion in ATK but i dont find any possibility to do that. Between that ohmic and schottky contact I want set a graphene nanoribbon and than investigate gate and voltage depandece of i-v curves. Did somebody have an idea how i can do that?
Or maybe there is any tutorials for such device and problems?

Any advice will be great

Thank you

IKgut

[Anders Blom]

Whether the contact is ohmic or Schottky is something you get as a result of the calculation with ATK, it's not an input parameter.

[zhangguangping]

Whether the contact is ohmic or Schottky is something you get as a result of the calculation with ATK, it's not an input parameter.

Dear Blom，

From the result,if the IV curve has a linear dependent on the bias, then the contact is ohmic contact. If it is non-linear, then it is Schottky contact.　Is it right?

Thanks.

[Anders Blom]

The Schottky-type contact is indicated by the fact that you have essentially no current at zero bias, and you have to raise the bias above some limit (the Schottky barrier) to get a finite current. Usually the current rises quite sharply above the barrier, linearly or even faster.

[Ikgut]

.....You mean its not important that I have two different electrodes (In/Au und Au)?.....Or how I can say ATk that there different workfunction on electrodes....I mean if i apply voltage do drain Electrode its important for bandstructure an electric properties how high or deep is my Fermi Level in non-equilibrium state ( I mean thats not equal for In/Au or Ti/Pt and so on)..Or I misunderstood something in programm....

[zhangguangping]

The Schottky-type contact is indicated by the fact that you have essentially no current at zero bias, and you have to raise the bias above some limit (the Schottky barrier) to get a finite current. Usually the current rises quite sharply above the barrier, linearly or even faster.

Thanks for yor clearity!

[Anders Blom]

With different electrodes it's a bit more complex, as a current in principle can flow even at zero bias. However, this current should build up an interface dipole layer to counter the different in work function, so that no current anyway doesn't flow at zero bias.

But the whole concept of workfunction is something you don't need in ATK because we treat the atoms as atoms, without any existing knowledge of their properties. We compute these properties instead. The whole Fermi level alignment etc is automatically done inside the calculation.

[Ikgut]

Thank you Andreas,

I think I though a bit false....Because T thought that I need different Electrodes for self-energay matrices. Different electrodes are different boundings to nanowire...and that influence my transmission spectra like in Landau Formula....If Im true I dont understand why I can ignore a chemical nature of my electrodes?


IKgut