Semiconductor Devices Principles: PN Diode, LED, Solar Cell, APD
Here is a detailed explanation of the principle, construction, and working of the following semiconductor devices:
PN Junction Diode
LED (Light Emitting Diode)
Solar Cell
Avalanche Photodiode
1. PN Junction Diode
Principle
A PN junction diode works on the principle of unidirectional current conduction — it allows current to flow in forward bias but blocks it in reverse bias.
Construction
Made by joining P-type and N-type semiconductors.
A depletion region forms at the junction due to diffusion of electrons
Astronomy Fundamentals: Celestial Bodies and Space Travel
Astronomy Fundamentals and Timekeeping
Ancient people used the Sun, Moon, stars, and tools like sundials to track time and seasons.
- A solstice is the longest or shortest day of the year.
- An equinox is when day and night are equal in length.
Models of the Universe
Understanding the structure of the cosmos evolved over time:
- The geocentric model states Earth is at the center of the universe.
- The heliocentric model states the Sun is at the center and planets orbit it.
- Elliptical orbits mean planets move in
Fundamental Concepts in Classical Mechanics Physics
Physical Quantities and Measurement
Physical Quantity: A property of a body or phenomenon that can be measured and expressed by a number and a unit (e.g., 5 m, 10 s, 3 kg). It allows us to describe physical laws quantitatively. A physical quantity is defined either by specifying how it is measured or by stating how it is calculated from other measurable quantities.
Unit of Measurement: A standard reference used for comparing quantities of the same kind. Example: meter (m) for length, second (s) for
Electromagnetic Waves, Sound & Wave Properties
Electromagnetic Waves, Sound & Wave Properties
Electromagnetic waves used in communication with wavelengths between about 1 cm and 20 cm are called (microwaves).
Electric signals that have only two possible values (on and off) are (digital signals).
A(n) (photon) is an electromagnetic wave that behaves like a particle.
Electromagnetic radiation with wavelengths between 400 and 750 billionths of a meter that can be detected by the human eye is (visible light).
A system of satellites, ground monitoring
Read MoreSemiconductor Electronics, P–N Junctions, Atomic Models & AC Physics
Semiconductor Electronics
Semiconductor
Semiconductor — These materials whose electrical conductivity lies between a conductor and an insulator are called semiconductors. At absolute zero they behave as insulators and at room temperature they behave as conductors.
Examples: Ge, Si, GaAs, CdS, CdSe, InP, etc.
Classification by Energy Band Theory
In solids there are three energy bands:
- The lower band is completely filled by electrons and is called the valence band (VB).
- The upper band is called the conduction
Electric Charge, Fields, Potential and Current
Electric Charge and Electric Field
Electric charge — it is a property of a body; charged bodies exhibit attraction and repulsion.
Electric field
Electric field — the sphere around a source charge in which a test charge would experience a force is called the electric field.
Electric field lines
Electric field lines — an electric field is represented by imaginary lines of force which are called electric field lines.
Properties of field lines
- They are imaginary lines of force.
- They are not closed (they