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.
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