Question

A Pure semiconductor has
A. A finite resistance which decreases with temperature
B. A finite resistance that increases with temperature
C. A finite resistance that does not depend upon temperature
D. On finite resistance at 0 degree C.

Answer 1

A semiconductor is a kind of conductor in which electrical conductivity lies between that of a conductor and an insulator.
The semiconductors are classified as intrinsic and extrinsic semiconductors based on the level of purity.
Chemically pure semiconductors are called undoped semiconductors; they are free from impurities hence, it is known as an intrinsic semiconductor.

Complete step by step solution:
Semiconductors are classified into two types they are Intrinsic semiconductor and Extrinsic semiconductor.
Intrinsic Semiconductor:
An intrinsic semiconductor material is the most pure form and they have poor conductivity. It has the same numbers of negative carriers of electrons and positive carriers of holes. at any temperature above absolute zero temperature, there is a possibility that an electron in the lattice will be loose from its position, leaving an electron called a "hole".
when a voltage is applied, then the electron and the hole can give to a small current flow.
The conductivity of a semiconductor can be modified in terms of the band theory of solids. The band model of a semiconductor recommended that at ordinary temperatures there is a possibility that electrons can reach the conduction band and give to electrical conduction.
The intrinsic semiconductor differentiates between the properties of pure "intrinsic" silicon and the various properties of doped semiconductors.
So, the correct answer is option (A).

Note:
An intrinsic semiconductor is a pure semiconductor (i-type semiconductor).
This refers to holes in the valence band that are created by the thermally excited electrons.
It opposes the extrinsic semiconductor where the holes or electrons are occupied by an external atom which acts as an impurity.