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.
