carrier concentration in diodes

Discussion in 'General Electronics Chat' started by elisettynarendra, Sep 9, 2010.

  1. elisettynarendra

    Thread Starter Member

    May 17, 2010
    In an intrinsic Semiconductor number of free electrons 'n' = No. of holes 'p'
    np = (Ni^2) . where Ni is intrinsic concentration.
    but i came to know that this product holds good in case of p and n type materials ..where as addition of n type materials increases no of electrons ..
    and holes conc. is almost the same . then how can it be constant ?
  2. Papabravo


    Feb 24, 2006
    Well each time an electron moves a hole is left behind. The number of "free" electrons is a constant, albeit a large one, so it stands to reason that the addition of an "impurity" element leaves the resulting alloy electrically neutral. So the number of electrons and holes remains the same.