- #1
Denver Dang
- 148
- 1
Homework Statement
I currently reading about transistors in a solid state course. And the transistor is a MOFSET, which I have to describe. I can't really find a nice figure of the one I have in my book, so I will just try to explain my confusion.
It says that you make a MOFSET by having a p-doped substrate in which you have two n-doped regions (source and drain), which are connected by an oxide layer, which again is connected to a metal electrode (gate).
Now, when you "open" the gate, you repel the holes underneath the oxide layer, making "room" for electrons and attracting them, right ? And first when you apply a voltage, there is enough energy to make the electrons move from source to drain, or maybe I have misunderstood something ?
So, my main question is: Since the p-substrate has a lot of holes, why are the electrons from the two n-type regions not attracted to them, even when there is no gate or voltage applied ? Why do they first start to be attracted when the gate is opened, and making the oxide layer positive ?
Don't know if I have explained it in a good way, but I hope you understand.
Homework Equations
EDIT:
I actually have the figure from my book right here:
http://i.imgur.com/Qda9msK.png