Current-Voltage Graph for Diodes

The diode conducts only in the forward direction (forward bias) as long as a threshold p.d. of 0.6V is exceeded.There is zero current for negative voltage when the diode is in reverse bias.A diode is made by joining two different types of semiconductor together.This creates an energy barrier at the junction so no carriers can move across the barrier.This barrier can be overcome in the forward direction by the application of a small potential difference usually about 0.6V.In the reverse direction there is only a tiny leakage current. If the reverse potential difference is large enough the diode breaks down, forcing the charge carriers across the barrier and allowing large conduction in the opposite direction.