What is the meaning of Fermi level?
The Fermi Level is the energy level which is occupied by the electron orbital at temperature equals 0 K. The level of occupancy determines the conductivity of different materials.
What is forbidden energy?
The gap between valence band and conduction band is called as forbidden energy gap. As the name implies, this band is the forbidden one without energy. The forbidden energy gap if greater, means that the valence band electrons are tightly bound to the nucleus.
What is energy bands in solids?
In solid-state physics, the electronic band structure (or simply band structure) of a solid describes the range of energy levels that electrons may have within it, as well as the ranges of energy that they may not have (called band gaps or forbidden bands).
What are the three energy bands?
In a solid there are three type of energy band.
- Filled Band. As clear from its name it is that type of band, which is near to the nucleus, and it is completely full from electron.
- Valance Band. The last band of the atom is called valance band and the electron of that band is called valance electron.
- Conduction Band.
How energy band is formed?
Each band is formed due to the splitting of one or more atomic energy levels. Therefore, the minimum number of states in a band equals twice the number of atoms in the material. The reason for the factor of two is that every energy level can contain two electrons with opposite spin.
What are allowed and forbidden energy bands?
The ranges of allowed energies of electrons in a solid are called allowed bands. Certain ranges of energies between two such allowed bands are called forbidden bands—i.e., electrons within the solid may not possess these energies.
How many types of semiconductors are there?
There are two types of extrinsic semiconductors: p-type (p for positive: a hole has been added through doping with a group-III element) and n-type (n for negative: an extra electron has been added through doping with a group-V element).
What are the 2 types of semiconductors?
Two main types of semiconductors are n-type and p-type semiconductors. (i) n-type semiconductors. Silicon and germanium (Group 14) have very low electrical conductivity in the pure state.