Electricity - Semi-Conductors and p-n Junctions Flashcards
(9 cards)
What happens when a semi-conductor contains p-type and n-type in adjacent layers?
A p-n junction is formed
What is forward bias?
When electrons in conduction band of n-type move towards conduction band of p-type
What happens to electric field in forward bias?
Reduces the electric field
What is reverse bias?
When the diode is connected with the p-type connected to the negative supply terminal and the n-type to the positive
What are LEDs?
Forward biased p-n junction diodes that emits photons
What does forward biased potential difference across the junction cause?
Electrons to move from conduction band of n-type to conduction band of p-type
How are photons emitted in LEDs?
When electrons fall from conduction band into valence band either side of junction
What are solar cells?
p-n junctions designed so that a potential difference is produced when photons are absorbed
What does absorption of photons cause?
It provides energy to raise electrons from the valence band of the semi conductor to the conduction band
