Semiconductors -- role of displaced Silicon or Germanium

Discussion in 'General Electronics Chat' started by logearav, Nov 28, 2011.

  1. logearav

    Thread Starter Member

    Aug 19, 2011
    Revered Members,
    When we dope a pure Germanium or Silicon with pentavalent impurity or trivalent impurity, the dopant replaces Silicon or Germanium and bonds with neighbouring Si or Ge atom. That is Dopant takes the centre position and bonds with 4 neighbouring atoms.
    Now where do that replaced Si or Ge go in the crystal?
  2. Wendy


    Mar 24, 2008
    The dopant is usually 1 part per million, so your concept is a bit off. Just a very small dab will do you.
  3. thatoneguy

    AAC Fanatic!

    Feb 19, 2009
    I believe if you add too much doping, you end up with a conductor or insulator, rather than a semiconductor.
  4. Adjuster

    Well-Known Member

    Dec 26, 2010
    I think the OP is referring to the physical rearrangement of the basic atoms in the material, for instance if a silicon crystal is doped.

    In the case of alloying or difusion processes, I would guess there is a general shuffling about of atoms, so one would no more ask where the silicon had "gone" than where the iron atoms might "go" when additives are introduced to alloy steel.

    Perhaps somebody better informed could comment on modern ion implantation processes. Are these normally followed by diffusion or annealing processes to "heal" the crystal?