Valence Band

Q.

Indium antimonide has a band gap of 0.23 eV between the valence and the conduction band. Find the temperature at which kT equals the band gap.

Q.

When a semiconducting material is doped with an impurity, new acceptor levels are created. In a particular thermal collision, a valence electron receives an energy equal to 2kT and just reaches one of the acceptor levels. Assuming that the energy of the electron was at the top edge of the valence band and that the temperature T is equal to 300 K, find the energy of the acceptor levels above the valence band.

Q. Energy bands in solids are a consequence of,

1. Ohm's law
2. Heisenberg's uncertainty principle
3. Pauli's exclusion principle
4. Bohr's theory

Q. The number of silicon atoms per $m^3$ is $5\times {10}^{28}$. This is doped simultaneously with $5\times {10}^{22}$ atoms per $m^3$ of arsenic and $5\times {10}^{20}$ per $m^3$ atoms of indium. Calculate the number of electrons and holes. Given that $n_i=1.5\times {10}^{16}/m^3$. Is the material n-type or p-type?

Q. How the energy band is formed in crystals ?

1. Energy levels of their valence electrons are modified as they are very far from each other.
2. Crystalline solid contains very small number of atoms
3. Atoms on the crystals are moved away from each other
4. Energy levels of their valence electrons are modified as they are close to each other.

Q. How the energy band is formed in crystals ?

1. Energy levels of their valence electrons are modified as they are very far from each other.
2. Atoms on the crystals are moved away from each other
3. Crystalline solid contains very small number of atoms
4. Energy levels of their valence electrons are modified as they are close to each other.

Q. Energy bands in solids are a consequence of,

1. Ohm's law
2. Bohr's theory
3. Heisenberg's uncertainty principle
4. Pauli's exclusion principle

Q. How the energy band is formed in crystals ?

1. Atoms on the crystals are moved away from each other
2. Energy levels of their valence electrons are modified as they are very far from each other.
3. Energy levels of their valence electrons are modified as they are close to each other.
4. Crystalline solid contains very small number of atoms