The material made by the combination of a P-type semiconductor and an N-Type semiconductor is known as a diode. The N-type portion of a diode has electrons and the P-type has electron holes. There is a neutral region between these two semiconductors known as a junction barrier. The P-type portion of a diode is known as the anode and the N-type portion of it is known as the cathode. Normally there is a flow of electrons in the diode. An external potential is needed in prefect direction and quantity in order to make flow of current.