30/11/2017

Energy Band Diagaram ( Conductor, Semiconductor and Insulator )

Valance electrons or band
  • The electrons in the outer most orbit of an atom are called as valance electrons.
  • The valance electrons have highest energy. 
  • This band may be partially or completely filled. 
  • The partially filled band can accommodate more number of electrons.
Conduction band
  • It is band of electrons which are responsible for conduction of current in the conductor. 
  • All the electrons in the conduction band are free. 
  • The conduction of current through material is not possible if the conduction band is empty. 
  • The insulators have empty conduction band where it is partially filled for conductors.

Forbidden energy band
  • It is gap between conduction band and valance band on the energy level diagram.
  • The width of forbidden energy gap indicates bondage of valance electrons to its atom. 
  • Less the forbidden energy gap, less tightly valance electrons are bound to electrons and vice versa.

Classification of material on the bases of energy bands
  • The electrons of the lower or last orbit are closely bound with nucleus there are they does not play important role in the conduction process. 
  • The valance band and conduction band plays important role to decide electrical behavior of the material.
Conductor
  • It is substance or material in which electrical current easily passes through it i.e. copper and aluminum
  • The valance band and conduction band overlap each other which create small potential difference. 
  • This potential difference causes flow of electrons which constitute electrical current
  • The energy band diagram is shown in the figure A.

energy-band-diagram-of-conductor.png


Semi conductor

  • It is substance or material in which small electrical current easily passes through it i.e. silicon, germanium. 
  • The conductivity of semi conductor lies between insulator and conductor. 
  • The valance electron is completely filled whereas the conduction band is almost empty as shown in the figure B. 
  • However the energy gap ( forbidden gap ) between valance band and conduction band is very small ( 1 eV ). 
  • The electrical current allows to flow if small electric field applied across it. 
  • The semiconductor behaves as an insulator at room temperature or low temperature. 
  • However some electrons cross conduction band causes small electric current even at room temperature. 
  • As the temperature increases, more electrons pass through valance band to conduction band resulting conductivity increases. 
  • The semiconductor has negative temperature co – efficient of resistance because as the temperature increases electrical conductivity of semi conductor increases or resistance decreases. 
  • Finally we can say that the semi conductor material has
  Empty conduction band

  Full valance band

  Small forbidden energy gap between valance band and conduction band



energy-band-diagram-of-semi-conductor.png


Insulator

  • It is a substance or material in which electric current does not pass through it i.e. wood, glass, plastic etc. 
  • The valance band is full whereas the conduction band is empty as shown in the energy band diagram. 
  • The forbidden energy gap between valance band and conduction band is large ( 15 eV ). 
  • The electrons of the valance band require very high electric field in order to cross it and move in the conduction band. 
  • The electrons of the valance band do not have enough energy to cross and move towards conduction band therefore the conductivity of the insulator is almost zero. 
  • The resistance of the insulator decreases with increase in the temperature therefore it has negative temperature co – efficient.


energy-band-diagram-of-insulator.png

You may also like :






7 comments:

  1. Professionally written blogs are rare to find, however I appreciate all the points mentioned here. I also want to include some other writing skills which everyone must aware of.
    กล่อง รองเท้า

    ReplyDelete
  2. How is solar power created? To create solar power, you'll need a solar panel, which is made out of at least one solar cells. Zonnepanelen

    ReplyDelete
  3. Extremely intriguing online journal. A lot of web journals I see nowadays don't generally give anything that I'm keen on, however I'm most definitely inspired by this one. Recently felt that I would post and let you know. energia fotovoltaica castellon

    ReplyDelete
  4. Employments like upkeep and establishment don't require a long haul preparing and are along these lines progressively favorable for the individuals who don't have numerous aptitudes and are jobless. Zonnepanelen installateur

    ReplyDelete
  5. Web templates are tools that are used in the separation of content from web design's presentation and mass web documents production.https://onohosting.com/

    ReplyDelete
  6. Basically, web templates can be described as ready made web -pages that one can use to make a web site within a short time.https://onohosting.com/

    ReplyDelete
  7. I appreciate the real-world examples shared on newgrowthelectric.com. They make learning practical.Panel Services New Growth Electric

    ReplyDelete