p-n Junctions Flashcards
How can you increase the conductivity of a semiconductor?
Doping
What are extrinsic semiconductors?
Semiconductors that have undergone doping
How many outer electrons does an impurity atom that is used for n-type doping have?
5
How many outer electrons does an impurity atom that is used for p-type doping have?
3
Do p-type and n-type conductors have charges?
No they are both overall neutral
In n-type semiconductors where are the free electrons found?
In the conduction band
In p-type semiconductors where are the ‘holes’ found?
In the valence band
Where is the fermi level located?
Where change carriers (free electrons or holes) are likely to be
In n-type semiconductors what happens to the fermi level?
It’s increased
In p-type semiconductors what happens to the fermi level?
It is decreased
When a p-type semiconductor and a n-type semiconductor join together what is produced?
A p-n junction
What’s another name for a p-n junction?
A diode
Use band theory to explain how LEDs work
Electron from the n-type conduction band move toward the p-type conduction band. When the electrons are in the p-n junction they fall from the conduction band to the valence band where they pair with a ‘hole’ and a photon is emitted
What is the photovoltaic effect?
When a potential difference is produced when photons enter the depletion layer
