ii p type semic like Al B In etc The dopant has one valence

Last updated: 6/21/2023

ii p type semic like Al B In etc The dopant has one valence electron less than This is obtained when Si or Ge is doped with a trivalent impurity Si or Ge and therefore this atom can form covalent bonds with neighbouring three Si atoms but does not have any electron to offer to the fourth Si atom So the bond between the fourth neighbour and the trivalent atom has a vacancy or hole as shown in Fig 14 8 Since the neighbouring Si atom in the lattice wants an electron in place of a hole an electron in the outer orbit of an atom in the neighbourhood may jump to fill this vacancy leaving a vacancy or hole at its own site Thus the hole is available for conduction Note that the trivalent foreign atom becomes effectively negatively charged when it shares fourth electron with neighbouring Si atom Therefore the dopant atom of p type material can be treated as core of one negative charge along with its associated hole as shown in Fig 14 8 b It is obvious that one acceptor atom gives one hole These holes are In addition to the intrinsically generated holes while the source of conduction electrons is only intrinsic generation Thus for such a material the holes are the majority carriers o