Basic Electronics Engineering and Basic Definitions

 Basic Electronics Engineering

UNIT – I: Semiconductor Fundamentals

Energy Band Theory, Conductors, Semiconductors and Insulators, Intrinsic Semiconductors, Extrinsic Semiconductors, Donor and Acceptor Impurities, Carrier Concentration, Drift Current, Diffusion Current, Hall Effect, PN Junction Formation, Depletion Region, Barrier Potential, Junction Capacitances and Semiconductor Materials for Electronic Applications.

UNIT – II: Diodes and Special Semiconductor Devices

PN Junction Diode Characteristics, Diode Current Equation, Diode Models, Zener Diode Characteristics and Voltage Regulation, Schottky Diode, Varactor Diode, PIN Diode, Tunnel Diode, Avalanche and Zener Breakdown Mechanisms, Applications of Special Semiconductor Diodes.

UNIT – III: Bipolar and Field Effect Transistors

Bipolar Junction Transistor (BJT) Construction, Transistor Action, Transistor Currents, Transistor Configurations, Input and Output Characteristics, Junction Field Effect Transistor (JFET) Construction and Characteristics, MOSFET Construction, Depletion and Enhancement MOSFETs, Transfer Characteristics and Comparison of BJT and FET Devices.

UNIT – IV: Power Semiconductor Devices

SCR Construction and Operation, SCR Characteristics, Triggering Methods, DIAC, TRIAC, UJT, IGBT, Switching Characteristics, Protection Techniques and Applications of Power Semiconductor Devices in Electronic Systems.

UNIT – V: Optoelectronic and Microwave Semiconductor Devices

Light Emitting Diodes (LEDs), Laser Diodes, Photodiodes, Phototransistors, Opto-Couplers, Solar Cells, Display Devices, Gunn diode, IMPATT Diode, TRAPATT Diode, BARITT Diode, Microwave Semiconductor Devices and their Applications in Communication and Sensing Systems.

Basic Electronics Engineering Basic Definitions

UNIT – I: Semiconductor Fundamentals

Energy Band Theory

Energy Band Theory explains that electrons are arranged in different energy bands separated by forbidden energy gaps.

Conductors

A conductor is a material in which the valence band and conduction band overlap ( Eg​=0 eV ), allowing electrons to move freely.

Semiconductors

A semiconductor is a material with a small energy band gap between the valence band and conduction band (Si: Eg​=1.1 eV, Ge: Eg​=0.67 eV, GaAs: Eg​=1.41 eV).

Insulators

An insulator is a material with a large energy band gap between the valence band and conduction band ( Eg​>5 eV ), preventing electrons from reaching the conduction band.

Intrinsic Semiconductors:

An intrinsic semiconductor is a pure semiconductor without any added impurities, having an equal number of electrons and holes.

Eg.  Silicon (Si), Germanium (Ge).

Extrinsic Semiconductors:

An extrinsic semiconductor is a semiconductor formed by adding impurities to a pure semiconductor.

P-type Semiconductor (Doped with trivalent impurities such as Boron)

N-type Semiconductor (Doped with pentavalent impurities such as Phosphorus)

Donor Impurity

A donor impurity is a pentavalent impurity that donates a free electron to a semiconductor.

Donor Impurities: Phosphorus (P), Arsenic (As), Antimony (Sb)

Acceptor Impurity

An acceptor impurity is a trivalent impurity that accepts an electron and creates a hole in a semiconductor.

Acceptor Impurities: Boron (B), Aluminium (Al), Gallium (Ga)

Carrier Concentration

Carrier concentration is the number of free charge carriers (electrons or holes) present in a unit volume of a semiconductor.

Drift Current

Drift current is the current produced by the movement of charge carriers due to an applied electric field.

Diffusion Current

Diffusion current is the current produced by the movement of charge carriers from a region of high concentration to a region of low concentration.

Hall Effect

Hall Effect is the generation of a transverse electric field (or Hall voltage) when a current-carrying conductor or semiconductor is placed in a magnetic field.

PN Junction Formation:

PN junction formation is the process of joining P-type and N-type semiconductors to form a PN junction.

Depletion Region

The depletion region is a region depleted of free electrons and holes due to recombination.

Barrier Potential

Barrier potential is the voltage developed across the depletion region that prevents the movement of charge carriers.

Typical Values: Silicon (Si): 0.7V, Germanium (Ge): 0.3V

Junction Capacitances

Junction capacitance is the capacitance developed across the depletion region of a PN junction.

Types of Junction Capacitance:

Transition (Depletion) Capacitance – under reverse bias.

Diffusion Capacitance – under forward bias.