Why does the conductivity of a semiconductor increase with increase in temperature?
The electrical conductivity of a semiconductor increases with increase in temperature because with increase in temperature the electrons overcome the energy barrier between the valence band and the conduction band easily.
The higher the temperature , i.e. the more kinetic energy the carriers have, the faster they will meet a scattering center. So in a simple model the higher the temperature the smaller the mobility. With increasing temperature, phonon concentration increases and causes increased scattering.
- In case of semiconductors as the temperature increases the electrons in the valence band get excited and jump into the conduction band and hence the conductance increases resulting in the dwindling of resistance. As resistance is directly proportional to resistivity, resistivity decreases, too.
- Hence with increase in temperature, number of carriers in the semiconductor material increases and which leads to increase in conductivity of the material. So we call the semi-conductor material have negative temperature coefficient i.e. with increase in temperature, resistance decreases.
- Electron mobility. In solid-state physics, the electron mobility characterizes how quickly an electron can move through a metal or semiconductor, when pulled by an electric field. There is an analogous quantity for holes, called hole mobility.
Updated: 2nd October 2019