Basics of Diodes

Diodes are semiconductor devices that typically allow the flow of electric current in one direction.
The principles and operation of diode are governed by semiconductor physics.
The key elements of a diode are the N-type and P-type semiconductors.
When assembled together, they form a PN junction that gives the diode its unique properties.

Characteristics of Diodes

In the forward bias condition, a diode permits current to flow, provided the applied voltage is above a certain threshold (usually around 0.7V for silicon diodes).
The reverse bias condition results in a very small reverse current known as leakage current. However, if the reverse voltage becomes too high (reaches the breakdown voltage), a large current will flow.
The I-V characteristic curve of a diode illustrates its behaviour in forward and reverse bias conditions.

Types of Diodes

Rectifier diodes are most commonly used in power supply circuits to convert alternate current (AC) into direct current (DC).
Zener diodes are specifically designed to operate in the breakdown region for voltage stabilisation in many circuits.
Light Emitting Diodes (LED) convert electrical energy into light and are widely used in many lighting and indication applications.
Photodiodes convert light into electric current, used in many applications including detectors and communication systems.

Applications of Diodes

In rectification, diodes are used in power supplies to convert AC into DC.
Diodes can be used in clipping and clamping circuits, where certain voltage levels are selectively clipped off or shifted.
Diodes are also used in protection circuits to protect sensitive components from voltage spikes.

Special Mention: Diode Limitations

Reverse Recovery Time refers to the time required for a diode to switch from the conducting state in forward bias to the blocking state in reverse bias.
Peak Inverse Voltage (PIV) or Peak Reverse Voltage (PRV) is the maximum voltage a diode can withstand in the reverse bias condition before breaking down.
Diodes also introduce a small voltage drop when conducting, which can be accounted for in circuit design.

Remember: understanding diodes entails mastery of both theoretical concepts and practical applications in circuit design. Always refer to the characteristics and datasheets for a specific diode for its proper use in circuitry.