---
+ Post New Thread
Results 1 to 6 of 6
  1. #1
    Full Member level 5
    Points: 7,870, Level: 21
    usernam's Avatar
    Join Date
    Mar 2004
    Posts
    268
    Helped
    132 / 132
    Points
    7,870
    Level
    21

    Electron mobility in silicon

    Why is electron mobility higher than hole mobility in Silicon?
    And is this reason why N-MOS on resistance is lower than P-Mos on resistance?

    Thnx

    •   Alt16th November 2005, 15:42

      advertising

        
       

  2. #2
    Full Member level 5
    Points: 3,276, Level: 13

    Join Date
    Jan 2005
    Location
    Asia
    Posts
    311
    Helped
    22 / 22
    Points
    3,276
    Level
    13

    Re: Electron mobility in silicon

    hi...

    The mobility of any particle is actually related to inertia which in turn is directly related the mass of that particle.

    The effective mass of electrons in silicon is 0.26 m0 and the effective mass of holes is 0.36 m0.
    and also the the scattering time may differ for both carrier types
    and hence the mobility of electrons is more than holes.

    And secondly, the mobility is directly related to resistance. hence this conclusion is true about the resistance of NMOS / PMOS. However note that this may not always be the case as the fabircation techniques and materials used also effect the resistance.

    Thanks...bye



    •   Alt17th November 2005, 06:31

      advertising

        
       

  3. #3
    Full Member level 5
    Points: 7,870, Level: 21
    usernam's Avatar
    Join Date
    Mar 2004
    Posts
    268
    Helped
    132 / 132
    Points
    7,870
    Level
    21

    Electron mobility in silicon

    How is the effective mass of electrons and holes in silicon calculated. Shouldn't they be equal??
    After all a hole is just the absence of an electron rite?



    •   Alt18th November 2005, 17:10

      advertising

        
       

  4. #4
    Member level 3
    Points: 1,723, Level: 9

    Join Date
    Nov 2004
    Posts
    60
    Helped
    0 / 0
    Points
    1,723
    Level
    9

    Re: Electron mobility in silicon

    Hi,There is difference energy between the hole particle and free electron particle
    so always the energy of hole is smaller than electrons by this we deduce that we
    must have different effective mass and also mobilities.



  5. #5
    Full Member level 1
    Points: 2,116, Level: 10

    Join Date
    Aug 2004
    Posts
    96
    Helped
    5 / 5
    Points
    2,116
    Level
    10

    Electron mobility in silicon

    All particles have mass, in this case the hole have more mass than electron, for this reason the electron mobility is higher than hole mobility. If you want learn more about this topics, you should read this book:

    Microelectronics by Millman



  6. #6
    Advanced Member level 5
    Points: 17,526, Level: 32

    Join Date
    Oct 2005
    Location
    India
    Posts
    1,804
    Helped
    256 / 256
    Points
    17,526
    Level
    32

    Re: Electron mobility in silicon

    well you would have learnt that the hole actually acts like a positive charge and hence there is more effective mass when considering a hole
    to understand better hole is moving in the valence band and electron in the conduction band



+ Post New Thread
Please login