Adding pentavalent or trivalent elements to pure semiconductor is called doping Or we can say that adding impurities to pure semiconductor is called doping.Doping converts intrinsic semiconductor to extrinsic semiconductor.
Why we use doping?
In electronics sometime such devices need extrinsic semiconductor that’s why doping is done and to break covalent bond of semiconductor we often use process of doping.
How covalent bond break by doping
Doping means adding impurities in pure semiconductor.When we add trivalent element or material to pure semiconductor it creates hole in
it as shown in the figure, this hole carries positive charge, now in this material positive charge is more than negative charge due to shortage of electron in covalent bond.After adding impurities this bond becomes weak instead of pure semiconductor covalent bond due to shortage of electrons.After doping semiconductor becomes weak and its covalent bond can be break easily by Applying less amount of heat.
Courtesy:Zamarak Khan Kasi