Hint: The materials which have a conductivity between conductors and non-conductors or insulators are known as semiconductors. Compounds such as germanium or silicon, or gallium arsenide, or pure elements can be semiconductors. There are theories, properties, and mathematical approaches which govern semiconductors.
Complete step by step solution:
Types of semiconductors: semiconductors are classified into the following two types,
(1) Intrinsic semiconductor:
The semiconductor material made up of only a single type of element is an intrinsic semiconductor, which is made to be pure chemically.
For example, germanium (Ge) and Silicon (Si) have four valence electrons known as tetravalent elements are the most common type of intrinsic semiconductor materials.
(2) Extrinsic semiconductor:
Adding impurities as a small number of suitable replacement atoms to improve the conductivity of semiconductors and the process of adding impurities to pure semiconductors is called doping. Based on this process, the extrinsic semiconductor can be further classified into two types,
(a) n-type semiconductor
(b) p-type semiconductor
Given, (i) Ge is tetravalent, and In is a trivalent element. When Ge is doped with In, the p-type semiconductor is obtained.
(ii) Selenium (Se) is tetravalent and phosphorous (P) is pentavalent. Then Se is doped with P, the n-type of semiconductor is obtained.
Note: In an n-type semiconductor, conductivity due to electrons which are majority charge carriers, and minor charge carriers are holes. Similarly, the conductivity of p-type semiconductors due to major charge carriers holes and minor charge carriers electrons. Since the number of charge carriers electrons increases due to the addition of an impurity, and during doping in p-type semiconductors leaves an absence of an electron in the impurity forms holes.