The substances whose conductivity lies between 10-⁶ to 10⁴ ohm-¹ . The range lies between conductors and insulators.
1. n-type :-
These type of semiconductors have excess electrons present in the lattice that are responsible for the conduction.
These are formed when the group 14 elements like Silicon are doped with group 15 elements like P and As. The group 14 elements have 4 valence electrons and group 15 elements have 5 valence electrons . One extra electron present in the lattice help in conduction of electricity , as it is free to jump or move freely.
This type of semiconductor is deficit in electrons and there are vacancies in the lattice also known as holes. The electrons from neighboring atoms jump to occupy the holes , thus creating new hole. This way the electricity flows due to the holes created.
These are formed when group 14 elements like Silicon are doped with group 13 elements like Aluminum. Aluminum is having 3 valence electrons ,and silicon is having 4 electrons . Thus a hole is created as shown below which leads to the conduction of electricity.