Diodes : A diode is formed by joining two equivalently doped P-Type and N-Type semicon-ductor. When they are joined an interesting phenomenon takes place. . The P-Type semiconductor has excess holes and is of positive charge. The N-Type semiconductor has excess electrons. At the point of contact of the P-Type and N-Type regions, the holes
in the P-Type attract electrons in the N-Type material. Hence the electron diffuses and occupies the holes in the P-Type material. Causing a small region of the N-type near the junction to loose electrons and behaves like intrinsic semiconductor material, in the P-type a small region gets filled up by holes and behaves like a intrinsic semiconductor. Rectifiers : A rectifier is an electrical device that converts alternating current (AC), which periodically reverses direction, to direct current (DC), which flows in only one direction. The process is known as rectification.