Electricity - Conductors, Semi-Conductors, and Insulators Flashcards
(12 cards)
What is the valence band?
The lower energy levels of electrons
What is the conduction band?
The higher energy level of electrons
What must there be for conduction to occur?
- Electrons free to move in conduction band
- Spaces in energy bands for electrons to move into
What is the band gap like between conductors?
No band gap
What does it mean if there is no band gap?
It means that electrons can move freely between the valence band and conduction band
What is the band gap like in insulators?
A large gap between valence and conduction band
Why can’t insulators conduct?
The valence band is full because no electrons can move into conduction band. There are no electrons in conduction band so cant conduct
What is the band gap like in semi-conductors?
They have a small gap between valence and conduction band
Why can semi-conductors conduct at room temperature?
There is enough energy for electrons to move to conduction band, this allows some conduction
What happens when increasing temperature in semi-conductors?
Conductivity increases
How else can conductivity in semi-conductors increase?
Doping them with specific impurities
What does doping result in?
Two types of semi-conductors:
- p-type
- n-type
