A p-n junction is an interface or a boundary between two semiconductor material types, namely the p-type and the n-type, inside a semiconductor.
Barrier Potential: The electric field that is produced in the depletion region acts as a barrier. External energy must be exerted to allow the electrons to get through the barrier of the electric field. The potential difference required for the electrons to be passed across the electric field is called the potential barrier. The barrier potential of a P-N junction depends on the type of material, amount of doping and temperature of the semiconductor. For silicon it is about 0.7V, for germanium, it is about 0.3V.