The circuit simplifies to:
\[ Y = \overline{\overline{A} \cdot \overline{B}} = \overline{\overline{A}} + \overline{\overline{B}} = A + B \]
(De-Morgan’s law)
A pure silicon crystal with 5 × 1028 atoms m−3 has ni = 1.5 × 1016 m−3. It is doped with a concentration of 1 in 105 pentavalent atoms, the number density of holes (per m3) in the doped semiconductor will be: