Diodes are the basic building blocks for most semiconductor devices. They are part of the bipolar family of devices. Diodes consist of two semiconductor materials, one doped with a deficiency of electrons called p-type material, and the other side is doped with an extra abundancy of electrons called n-type material. A process known as doping the material is what makes some parts of the diode p-type and the other parts n-type. While growing the semiconductor crystal, a small amount of arsenic or phosphorus can be mixed in with the process and dope the material. To change the type of material from p to n type, one can add some n-type chemicals to swamp out the p-type materials already in the 'substrate'.