How diode works - what happens inside a diode when it comes into contact with power

Diode is a p-type and n-type materiel semiconductor device. This allow to pass the current flow in only one direction (called the diode's forward direction), while blocking current flow in the opposite direction (called the reverse direction). At this time there are many types of diodes uses in electronics designing like schottky diode, LED (light emitting diode), zener diode, photodiode, tunnel diode and many types.

Working

Small voltages to be required to operate diodes, for silicon diodes 0.6v would be need to get conduct and 0.3v required for germanium diodes.

When a battery negative connect to diode N-type (cathode) and positive connect to P-type (anode), it says "Forward-bias". In this condition depletion zone shrinks and holes flow p-type side and electrons flow n-type side, it's mean current flows.

However if we connect battery in reverse direction, it says "Reverse-bias". The result is that, depletion zone gets wider, this depletion region acts as an insulator preventing current from flowing through the diode and all of the electrons be gathered p-type end and holes at n-type end. In this condition no current flows in circuit because electrons and holes are moving in wrong direction.

So we can say diode works as a check valve that allow to water flow in one direction only.

When water pressure on left overcomes the restoring force of spring, the gate is opened and water is allowed to flow. When water pressure is from right to left, the gate is pressed against the solid stop and no water is allowed to flow. Spring restoring force is analogous to 0.6V needed to forward bias a Si diode.