What are n-type semiconductors?

Hint: It is a type of Semiconductors. Differences between Lattice structures of n-type and p-type semiconductor will help in solving the question.

Complete step by step answer:
Semiconductors are made up of materials exhibiting electrical conductivity between conductors and non-conductors. Semiconductors are made doping pure elements with pentavalent or trivalent impurities, which results in more electrons or more holes in the latter case. The function of semiconductors is to regulate the flow of electric current into the equipment.
Semiconductors are two types:
1. N-Type
2. P-Type
N-Type Semiconductors: N-Type semiconductors are formed by doping pure elements element such as Silicon (Si) and Geranium (Ge) having 5 valence electrons with pentavalent impurity such as Antimony (Sb), Arsenic (As) or phosphorus (P) having four valence electrons. Four out of 5 electrons of dopant form a covalent bond with pure elements (Si & Ge) and one electron remains free, resulting in overall negative charge of the molecule. Hence it is known as n-type semiconductor.
The crystal lattice of the material is generally neutral in charge but with the increase in the concentration of doping agents in the pure element increases the ions in the crystal lattice, making it negatively charged. The free electrons in the crystal lattice when subjected to electric charge helps in free movement of electrons along the lattice and helps in the electric conduction.

Note:-
While defining n-type and p-type semiconductor, differences between doping agents like pentavalent and trivalent elements should be taken care of. Generally while solving the questions students get confused between which doping agents to be used in the semiconductor material. Also direction of current flow to be known while dealing with n-type and p-type semiconductor.