Conduction In Conductors And Semiconductors

Conduction in conductors and semiconductors

Mobility μ: In good conductors like metals, free electrons exist in abundance. They are supposed to be accelerated under the influence of electric or magnetic field as per ballistic (dynamics) laws. But in practice it is found that the electrons move with a constant velocity proportional to the field. The reason for this is the random nature of the electron movement involved in repeated collisions. The loss of energy during collisions is supplemented due to acceleration caused by the applied field E. Thus it is observed that the random motion of electrons when resolved in the direction of the field, the electrons acquire a constant speed called the drift speed v that is proportional to the field E (V /m) and velocity v is in metres/second.

where μ is the constant of proportionality. μ is called as mobility. It is measured as m2/V-s. Mobility of electrons and Holes due to the influence of electric field is given in Eq. (2.10). Because of the lighter mass of electrons, electrons have large values of mobility μncompared to Hole mobility μp.

For a given excitation energy to electrons (due to applied field strength), electrons move faster in Germanium semiconductor when compared to Silicon semiconductor, because of small forbidden band-gap energy in Germanium semiconductors. So Germanium semiconductor devices find their use in high-frequency applications.

admin

Share
Published by
admin

Recent Posts

Standby Generators and Custom Commercial Generators for Sale

Humankind has become extremely dependent on electricity, without it we can’t run the household, keep…

4 years ago

Electrical Machine Interview Question And Answer

[1] Define the term synchronous speed [Dec-2003] For synchronous machines there exists a fixed relationship…

7 years ago

Transformer Interview Questions With Answer

We shared a lot of interview questions on electrical machines, power system and power electronics. Today we…

7 years ago

What Is Diesel Power Station

DIESEL POWER STATION A generating station in which diesel engine is used as the prime…

7 years ago

Synchronous Generator Interview Questions

Q:Why syn. generators are used for the production of electricity? A:synchronous machines have capability to…

7 years ago

Hydro Power Station

Hydro-electric Power Station A generating station which utilises the potential energy of water at a…

7 years ago