A n-type semiconductor like silicon with pentavalent impurity like that of Phosphorous. Here, among the five valance electrons of phosphorous atom, four of them pair-up with the valance electron as a results fifth electron of phosphorus remain unpaired and is available freely to aid the process of conductions. Once the conduction is initialized these free electron start move by leaving their respective atom. This result in the formation of immobile core in crystal lactic which consist of positively charged phosphorous atom.