Question

Germanium is an example of a/an
(A) Intrinsic semiconductor
(B) n-type semiconductor
(C) p-type semiconductor
(D) Insulator

Answer 1

Hint: Here, you are asked to determine the type of substance/material of germanium. Whether it is an intrinsic semiconductor or an extrinsic semiconductor and in that too determine whether it is an n-type semiconductor or a p-type semiconductor or it is an insulator. In order to answer this question, you need to consider the electronic configuration of the element Germanium. You can tell its type by seeing the number of electrons in a Germanium atom.

Complete answer:
Germanium is an element from the periodic table with atomic number equal to 32. Symbol of Germanium is Ge. The outermost orbit of Germanium consists of four electrons. The Germanium atom uses these atoms to form covalent bonds. The arrangement of electrons is such that they are very stable and do not act as a conductor efficiently.Intrinsic semiconductor: It is the purest form of semiconductor. Intrinsic semiconductors are undoped semiconductors.

Extrinsic semiconductor: When a certain semiconductor is doped with impurities, then the semiconductor is known as extrinsic semiconductor. Now, it depends on what type of impurity is doped.n-type semiconductor: If the impurity consists of pentavalent elements, then the semiconductor is known as n-type semiconductor. Here, the majority carriers are the electrons.

p-type semiconductor: If the impurity consists of trivalent elements, then the semiconductor is known as p-type semiconductor. Here, the majority carriers are the holes.So, if you consider Germanium, it is neither trivalent and nor pentavalent, it has four electrons in its outermost orbit. The Germanium element is not doped with any impurities. Hence, it is an intrinsic semiconductor.So, Germanium is an example of an intrinsic semiconductor.

Hence, option A is correct.

Note:You need to remember the definitions of each term mentioned in the above solution. Intrinsic semiconductors are those which are in their purest, not doped. Extrinsic semiconductors are those which are doped with impurities. If the impurity is pentavalent, it is known as n-type semiconductor and if it is trivalent, it is known as p-type semiconductor.