Question

Which type of behaviour is shown by a pure Germanium at absolute zero temperature?
1. Conductor
2. Semiconductor
3. Insulator
4. Can't predict

Answer 1

Correct Answer - Option 3 : Insulator

CONCEPT:

• The material which is not a good conductor or a good insulator is called a semiconductor.
• For example: Silicon, Germanium, etc.
• The charge carriers which are present in more quantity in a semiconductor compared to other particles are called the majority charge carrier.
• The impurity atoms added are called dopants and semiconductors doped with the impurity atoms are called extrinsic or doped semiconductors.
• The pure form of semiconductor is called an intrinsic semiconductor.

Intrinsic Semiconductors:

• A pure semiconductor is called an intrinsic semiconductor. It has thermally generated current carriers.
• They have four electrons in the outermost orbit of the atom and atoms are held together by a covalent bond.
• Fermi energy level lies at the center of the conduction band (C.B) and valence band (V.B) in an intrinsic semiconductor.
• Because of fewer charge carriers at room temperature, intrinsic semiconductors have low conductivity so they have no practical use.

EXPLANATION:

• An ideal, perfectly pure semiconductor (with no impurities) is called an intrinsic semiconductor.
• At absolute zero temperature valence band is full of electrons and the conduction band is empty, hence there are no free electrons in the conduction band and holes in the valence band.
• The charge carrier concentration is zero. Hence intrinsic semiconductor behaves like an insulator
• Hence, at zero temperature the intrinsic semiconductor behaves like an insulator. The correct option is 3.