Semiconductors

What is a semiconductor?

Semiconductors, sometimes called integrated circuits (ICs), are usually made of pure elements, typically silicon or germanium. The semiconductors conduct more electricity than an insulator, such as glass, but less than a pure conductor, such as copper.

In a process called doping, small amounts of impurities are added to these pure elements, causing large changes in the material’s conductivity. In other words, controlling the amount of current that pass through the material.

What are semiconductors used for?

Semiconductors are employed to make a lot of electronic devices, including diodes, transistors, and integrated circuits. Semiconductors are used in a lot of electronic products, as such as computers, tablets, smartphones, appliances, etc.

	Diodes
	The Semiconductor Diode The semiconductor diode is the simplest semiconductor device and can be found in almost any electronic circuit. Diodes are manufactured with germanium and silicon.
	Zener diode – Basic Operation – Applications The Zener diode is a special type of semiconductor device that allows the flow of current on the opposite direction of the arrow of the diode.
	Photodiode – How does it work? Photodiodes produce a leakage current that is directly proportional to light intensity. This leakage current flows in the opposite direction to the current in a conventional diode.
	Schottky Diode (Schottky Barrier Diode) These diodes are characterized by their switching speed and low voltage drop when they are forward biased. (typically 0.25 to 0.4 volts)
	LED – Light-emitting diode LED – Light-emitting diode Light-emitting diode (LED) is a special type of diode, that emits light when it is forward biased.
	7-segment Display This component used to show numbers in many electronic devices. It is very common to find LCDs in much electronic equipment, but there are many that still use the 7-segment display for its simplicity.
	Why is there a diode connected in parallel to a relay coil? The purpose of a diode connected in parallel to a relay coil (flywheel diode or freewheeling diode) is to avoid damaging some nearby components sensitive to high voltage.

	Transistors
	What is a Phototransistor? – Equivalent Circuit A phototransistor is a transistor that can work in two different ways: as a common transistor and as a phototransistor, using the light that illuminates this element as the base current.
	UJT – Unijunction Transistor – Equivalent model & circuit The UJT or Unijunction transistor is constituted by two polluted regions, with three external terminals: two bases and one emitter.
	PUT – Programmable Unijunction Transistor PUT – Programmable Unijunction Transistor. Main characteristics. PUT and UJT. Oscillator circuit design and waveforms. Frequency formula
	Darlington transistor The Darlington transistor is a special type of transistor with a high current gain. It consists of two internally bipolar transistors being connected in cascade
	Optocoupler (LED and phototransistor) The Optocoupler is a device that consists of a LED and a phototransistor. When the LED emits light, it illuminates the phototransistor causing a current to flow through it.
	FET – Field Effect Transistor (JFET) Field effect transistor or FET is a particularly interesting transistor and it can be of two types: the Junction Field Effect Transistor or JFET and the Metal-Oxide Semiconductor Field Effect Transistor (MOSFET).
	FET Characteristics (N-channel JFET) The N-channel JFET consists of a silicon bar of N-type semiconductor with two P type regions on both sides. JFET is a tri-terminal device whose terminals are called drain, source and gate.
	JFET Saturation and Breakdown regions JFET Saturation and Breakdown regions The JFET Saturation region In this region the JFET has some linear features that are used in amplification.
	JFET Cutoff and Linear regions JFET Cutoff and Linear regions JFET Cutoff region In this region, the current flowing from the Drain to the Source terminals of the JFET is zero (ID = 0).

	Power Electronics
	SCR (Silicon Controlled Rectifier) – Thyristor The SCR (Silicon Controlled Rectifier) is a 4-layer semiconductor device that works as an almost ideal switch.
	DIAC – Diode for Alternating Current. V-I characteristic DIAC is a bidirectional trigger diode, designed to trigger TRIAC and thyristors. DIAC is a voltage-triggered device
	SBS – Silicon Bidirectional Switch The SBS is a symmetrical low power device used on trigger applications. It has an additional terminal, which allows you to modify its trigger characteristics with small pulses of current.
	TRIAC Triac is a semiconductor device that belongs to the family of thyristor control devices. It is essentially two SCR connected in parallel and backwards, sharing the same gate.
	MOSFET Transistors – NMOS, PMOS MOSFET Transistors or Metal Oxide-Semiconductor (MOS) are field effect devices that use the electric field to create a conduction channel.

	Voltage regulators
	LM317 Variable Voltage Regulator Circuit LM317 characteristics. How the voltage regulator circuit works, Regulator circuit operation improvement
	Increase Output Voltage on 78XX Regulators To understand why the output voltage of an integrated circuit of this type increases, when we place a diode or a resistor at the “Adj” input