Question

At 0K temperature, a p-type semiconductor,
A. Has equal numbers of holes and free electrons
B. Has few holes but no free electrons
C. Has few holes and few free electrons
D. Doesn’t have any charge carries

Answer 1

In p-type semiconductor there is a conduction band and a valence band. Charge carriers move from the valence band to the conduction band to conduct the electricity. In p-type semiconductor the holes are majority carriers whereas the electrons are the minority carriers.

Complete answer:
Initially the conduction band is free from the charge while the valence band is fully filled with the charge. Since the p-type semiconductors doped with some impurities so it will have an acceptor level near the valence band.

For the conduction of her electricity, the electrons from the valence band must jump to the conduction band so that there will be some free electrons in the conduction band to conduct the electricity. But the electrons to jump from the valence band to the conduction band there should have an optimal amount of the energy and at the 0 K the electrons will not have that much energy to jump from the valence band to the conduction band.
So, at 0K the electrons will only be able to jump from the valence band to the acceptor level creating some holes in the valence band. Hence at 0K there will be some hole and there will not be any free electrons in the semiconductor.
Hence, at 0K temperature, a p-type semiconductor has few holes but no free electrons.

So, the correct answer is “Option B”.

Note:
In semiconductors the valence band is the highest range of electron energies in which electrons are normally present at absolute zero temperature, while the conduction band is the lowest range of vacant electronic states. There is some effect of the temperature on the conduction nature of the semiconductors. As the temperature rises then the electrons get the more energy to transit from one band to another for the conduction, so as the temperature increases then the conduction increases.