There are two main types of semiconductors namely; intrinsic semiconductors and Cloze (1): JXUwMDNkJXUwMDFkJXUwMDBjJXUwMDA2JXUwMDFiJXUwMDA3JXUwMDFkJXUwMDFhJXUwMDBh semiconductors.

Cloze (2): JXUwMDFjJXUwMDJiJXUwMDFmJXUwMDE5JXUwMDA3JXUwMDA5 is the introduction of impurities in semi-conductors to alter their electronic properties. An Cloze (3): JXUwMDMxJXUwMDA3JXUwMDFhJXUwMDA2JXUwMDFiJXUwMDA3JXUwMDFkJXUwMDFhJXUwMDBh semi-conductor is one which is pure enough such that the impurities in it do not significantly affect its electrical behavior. Intrinsic semi-conductors increase their conductivity with Cloze (4): JXUwMDMxJXUwMDA3JXUwMDBkJXUwMDExJXUwMDE3JXUwMDA0JXUwMDEyJXUwMDE2 in temperature unlike metals. 

An extrinsic semi-conductor is one which has been doped with Cloze (5): JXUwMDMxJXUwMDA0JXUwMDFkJXUwMDA1JXUwMDA3JXUwMDFiJXUwMDFkJXUwMDFkJXUwMDBjJXUw MDE2 to modify its number and type of free charge carriers present.

There are two types of extrinsic semiconductors namely Cloze (6): JXUwMDYzJXUwMDFiJXUwMDRl type and p type.

The n type semiconductor is formed by doping an intrinsic semiconductor with Cloze (7): JXUwMDI4JXUwMDE1JXUwMDBiJXUwMDFhJXUwMDE1JXUwMDE3JXUwMDE3JXUwMDBkJXUwMDA5JXUw MDBiJXUwMDFh atoms like phosphorous. A phosphorous atom has five electrons available for bonding four of which participate in forming covalent bonds with four neigbouring atoms of the pure semiconductor.

The Cloze (8): JXUwMDI4JXUwMDUwJXUwMDU0JXUwMDBkJXUwMDA5JXUwMDE1 semiconductor is formed by doping an intrinsic semiconductor with trivalent atoms like boron. A boron atom has Cloze (9): JXUwMDJjJXUwMDFjJXUwMDFhJXUwMDE3JXUwMDAw electrons available for bonding. All the three electrons participate in forming covalent bonds with three neigbouring atoms of the pure semiconductor. There is one electron less to complete the bonding.

The vacant place due to the missing electron is called a hole. A hole is positively charged.  In p type, holes become the majority charge carriers.