$C$ and Si both have same lattice structure, having 4 bonding electrons in each. However, $C$ is insulator…

$C$ and Si both have same lattice structure, having 4 bonding electrons in each. However, $C$ is insulator whereas $\mathrm{Si}$ is intrinsic semiconductor. This is because
  1. in case of $\mathrm{C}$, the valence band is not completely filled at absolute zero temperature
  2. in case of $C$, the conduction band is partly filled even at absolute zero temperature
  3. the four bonding electrons in the case of $C$ lie in the second orbit, whereas in the case of Si they lie in the third
  4. the four bonding electrons in the case of $\mathrm{C}$ lie in the third orbit, whereas for $\mathrm{Si}$ they lie in the fourth orbit

Solution

The four bonding electrons in the case of $C$ lie in the second orbit, whereas in case of Si they lies in the third orbit so loosely bounded valency electron in $\mathrm{Si}$ as compared to $\mathrm{C}$.

Asked in: NEET 2012 (Screening)

Practice more Semiconductors questions on Aicharya