When an electric field is applied across a semiconductor
A. electrons move from lower energy level to higher energy level in the conduction band.

B. electrons move from higher energy level to lower energy level in the conduction band.

C. holes in the valence band move from higher energy level to lower energy level.

D. holes in the valence band move from lower energy level to higher energy level.

The band gap for silicon is 1.1 eV.

(a) Find the ratio of the band gap to kT for silicon at room temperature 300 K.

(b) At what temperature does this ratio become one tenth of the value of 300 K? (Silicon will not retain its structure at these high temperatures)

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.

Hole is

An electric field is applied to a semiconductor. Let the number of charge carriers be n and the average drift speed b v. If the temperature is increased.

Why are elemental dopants for Silicon or Germanium usually chosen from group XIII or group XV?

We have valence electrons and conduction electrons in a semiconductor. Do we also have ‘valence holes’ and ‘conduction holes’?

When an electron goes from the valence band to the conduction band in silicon, its energy is increased by 1.1 eV. The average energy exchanged in a thermal collision is of the order of kT which is only 0.026 eV at room temperature. How is a thermal collision able to take some of the electrons from the valence band to the conduction band?

Sn, C, and Si, Ge are all group XIV elements. Yet, Sn is a conductor, C is an insulator while Si and Ge are semiconductors. Why?