Question

In extrinsic P and N type semiconductor materials, the ratio of the impurity atom to the pure semiconductor atoms is about
\[\begin{align}
  & A.\,1 \\
 & B.\,{{10}^{-1}} \\
 & C.\,{{10}^{-4}} \\
 & D.\,{{10}^{-7}} \\
\end{align}\]

Answer 1

Hint: The semiconductors with impurities present in them are called the extrinsic semiconductors. The semiconductors with no impurities in them are called the intrinsic semiconductors.

Complete step by step answer:
Mainly there are two types of semiconductors. They are intrinsic semiconductors and extrinsic semiconductors. The extrinsic semiconductors are further subdivided into two types, they are, n-type semiconductors and the p-type semiconductors.
In the case of intrinsic semiconductors, the number of electron concentration equals the number of hole concentration. Whereas, in the case of extrinsic semiconductors, the number of electron concentration and the number of hole concentration depends on the types of extrinsic semiconductors. In the case of the n-type semiconductors, the number of electron concentration will be more than that of the number of hole concentration, whereas, in the case of the p-type semiconductors, the number of electron concentration will be less than that of the number of hole concentration.
The ratio of the impure semiconductor atoms to the pure semiconductor atoms is about \[{{10}^{-7}}\].

So, the correct answer is “Option D”.

Note: The pure semiconductor is also called the intrinsic semiconductors. The reason being, the intrinsic semiconductors are not doped. If pentavalent impurities are added to the semiconductors, then, the resultant will be n-type extrinsic semiconductors. If trivalent impurities are added to the semiconductors, then, the resultant will be p-type extrinsic semiconductors.