Metal Work Function Question

[Hassan]

These are the posts made in this forum that talk about how the Gate Metal Work Function is treated in Atomistix. I wanted to clarify a few things.

The work function of the metalic region will determine where is the zero value of the gate potential. Thus, the effect of the work function is to shift the gate potential by a constant. You cannot set this parameter, and you need to make such corrections as post analysis. 
i.e. work function of electrode is 4 eV, work function of gate is 5 eV, then you must add -1 V to you gate potential axis as post analysis.

The gate electrodes are just electrostatic, and have no real "atomic" character, which would be needed to define a work function.

Question:
But without knowing the work function of this so called electrostatic region, how can one anticipate the changes of I-V as we move from two terminal to three terminal device with zero gate bias ?
Answer:
In principle yes, but this is only relevant if there is a gate current as well, but to describe such a real three-probe system you need the gate to be described atomistically as well, just as source and drain, and this formalism is not available in ATK.

So does this mean that the gate metal work function is in reference to whatever electrode metal is being used? So for example if I have a Copper electrode, then the ideal gate metal used has the same work function as that copper electrode? And if I intend to use another metal as the gate, then I simply subtract the difference from the electrode metal work function and gate metal work function from the Gate Potential Axis in my transfer characteristics curve?

Thanks!

[Hassan]

Helpp

[Anders Blom]

I don't know about "ideal", but the procedure you outlined is correct.

[ruyam]

Dear Anders Sir,

From what I learnt from the forum, gate metal has the same work-function as that of the metal and if we wish to modulate it, we need to do it in post analysis by simply subtracting the difference from the electrode metal work function and gate metal work function from the Gate Potential Axis in my transfer characteristics curve.
But, what if I don't have a symmetric device structure and both the electrodes I use are of different metal? So, how does ATK take the metal for gate? and how can I modulate it in post analysis to get the desired metal work function for the gate?

Thanks in advance.

regards,
ruyam

[Anders Blom]

What changes in this case is that the bias is no longer just the difference between the two electrode voltages, but the zero-point of the electrode voltages becomes a defined thing. In the normal case, without gates, only the different in left/right voltage matters, but in this case you should relate all voltages absolutely to the work function of the gate.

[ruyam]

Dear Sir,

I am unable to follow you on your reply. 
Can you please explain it with a numerical example like the quote in first reply in this post? Taking example as electrodes having workfunction W1, W2 and gate having workfunction W3? (electrodes and gate have different workfunctions alltogether in my structure).

[ruyam]

Hi QW Staff,

Reply is awaited.

[ruyam]

Hi QW Staff,

I am waiting for the reply on gate metal workfunction.

[tara]

Could you tell me what will be the work function of my gate metal if my source is p-doped and drain is n-doped??