Diodes:

A diode is a two-terminal electronic component that allows current to flow in one direction while blocking it in the opposite direction.

It is made of a p-n junction, where p refers to the positively doped region and n refers to the negatively doped region.

The most common type of diode is the semiconductor diode, which is typically made of silicon or germanium.

When the diode is forward-biased (positive voltage applied to the p-side and negative voltage to the n-side), it conducts current easily.

When the diode is reverse-biased (positive voltage applied to the n-side and negative voltage to the p-side), it has a very high resistance and almost no current flows.

Diodes are used in various applications such as rectifiers, voltage clippers, voltage regulators, and signal demodulation.

Bipolar Junction Transistors (BJTs):

BJTs are three-terminal devices consisting of three semiconductor regions: the emitter, base, and collector.

The two common types of BJTs are NPN (negative-positive-negative) and PNP (positive-negative-positive).

The operation of a BJT is based on the movement of both majority and minority charge carriers.

When a small current is applied to the base-emitter junction, it controls a larger current flow between the collector and emitter.

BJTs are classified into two types: NPN (N-type emitter, P-type base, and N-type collector) and PNP (P-type emitter, N-type base, and P-type collector).

They are commonly used for amplification and switching applications in electronic circuits.

Metal-Oxide-Semiconductor Field-Effect Transistors (MOSFETs):

MOSFETs are three-terminal devices used for amplification and switching in electronic circuits.

They are made of a metal gate electrode separated from the semiconductor channel by a thin insulating layer (oxide).

The two main types of MOSFETs are enhancement-mode and depletion-mode.

In an enhancement-mode MOSFET, no channel is formed between the source and drain when the gate voltage is zero. A positive gate voltage creates a conducting channel.

In a depletion-mode MOSFET, a conductive channel is already present between the source and drain when the gate voltage is zero. A negative gate voltage depletes the channel and reduces conduction.

MOSFETs offer high input impedance, low output impedance, and good switching characteristics.

They are widely used in integrated circuits (ICs), microprocessors, memory chips, and other digital devices