QUESTION 3 silicon with 10A14cc B atoms at the boiling point

QUESTION 3 silicon with 10A14/cc B atoms at the boiling point of Helium (4.2K) is p-type O insulator n-type O degenerate QUESTION 4 silicon with 10414/cc B atoms at 900C is O n-type p-type O insulator intrinsic

Solution

3)

Insulator

No doping happens at such low temperatures as enough thermal energy is not present for the electron to escape to conduction band.

4)

p-type.

Introduction of Boron introduces holes in the valence band of silicon.

5)

Goes down because intrinsic concentration is increasing.

For demiconductors, as temperature increases, no: of electrons in conduction band escaping the valence band increases and hence resistivity decreases.

d)

fourth choice is the anser as for the same reason mentioned.