# MOS capacitor flatband voltage

by antonantal
Tags: capacitor, flatband, voltage
 P: 219 Why is the flatband voltage of a MOS capacitor equal to the voltage corresponding to the energy difference between the work functions of the semiconductor and the metal of the gate? In other words, why and how are the energy bands bent when the gate-source voltage is zero?
 P: 4 Hello, i don't know if I've understood you right, because my english is not as good as it should be So, i try to explain like i've understood you. Well, there are two kinds of MOSFET First the enhancement transistor and then the depletion transistor. The second one transistor will conduct if U_GS is either positiv or negativ << and not zero >>! But at this point i'm not sure, so i'll repost when i've read my study documents at home and you still need it. I'll explain the functionality of a MOSFET to you later, because i don't know if this is the answer that you need and this theme is too big and complicated for answering for nothing. So, when this is what you are searching for, post again. regards URI ______________________________ hope my english is not too bad. My knowledge of electricity is not as bad, but my english ! So if you notice gramatical mistakes please improve me.
P: 219
 Quote by URI I'll explain the functionality of a MOSFET to you later, because i don't know if this is the answer that you need and this theme is too big and complicated for answering for nothing.
Thanks, but my question is not "how does a MOSFET work?". It is much more specific.

P: 70
MOS capacitor flatband voltage

 Quote by antonantal Why is the flatband voltage of a MOS capacitor equal to the voltage corresponding to the energy difference between the work functions of the semiconductor and the metal of the gate?
I am not exactly sure what you are asking but I think the answer is, because that's how the physicists chose to define flatband voltage. I mean, a voltage is the potential difference between two points, so those are the points they picked.

 Quote by antonantal In other words, why and how are the energy bands bent when the gate-source voltage is zero?
For why bands bend see section 2.3.5 of

Is gate and source, the anode and cathode of the MOS cap? Is so then,
for how see Figure 3.2.3 or Figure 3.2.4 with Va=0.