about the conductance

[mantun]

Hi!
I encountered a question that I don't understand. I calcalated the conductance of Au-ZnO-Au tunnel junctions with varying ZnO thickness. The result is that the dependence of conductance on thickness is u-like (that is to see, with increasing thickness, the conductance decreases first and then increases). Can you explain this?
Second question: Is the current calculated by ATK is only the contribution of direct tunneling , or it contains the contribution of thermionic injection?
Thanks in advance!

[Anders Blom]

Thermionic emission is also included. See http://quantumwise.com/documents/tutorials/latest/GrapheneDevice where this is discussed.

[mantun]

You mean that the thermionic emission is a new feature of the latest ATK version, and is not included in the former version?
Another question is that you don't apply about my first question in my post. Please check! Thanks in advance!

[Anders Blom]

No this tutorial was originally made with ATK 11.8. Thermionic emission is automatically captured in the models used in ATK and this has always been the case.

As for your first question, I have no idea.

[mantun]

Thank you for your reply! What about the version before
11.8 (Actually 08 version)? I am a owner of the 13.8 version, but I am used to use 08 version to keep consistent. Hope for your replay!

[Anders Blom]

As I said, it's native to the general formalism in ATK, so it's always been available.

[mantun]

I just came up with a strange point in my calculation of Au-ZnO-Au junctions. I found although the dependance of conductance on thickness of ZnO is u-like, the current of Au-ZnO-Au junctions under small bias voltage monotonously decreases with the thickness of ZnO. Is it normal? Would you please explain how it
happens?

[Anders Blom]

No I can't. That's too complex a question to just answering without knowing all details of the calculation. That's your job

[mantun]

Thank you for your suggestion!