Mnemonics: Semiconductor Electronics | Physics Class 12 - NEET PDF Download

Semiconductor Materials

Types: Silicon, Germanium, Gallium Arsenide

Mnemonic: "Sonia Grips Glowing Arcs"

Breakdown:

• Sonia - Silicon
• Grips - Germanium
• Glowing Arcs - Gallium Arsenide
  

Silicon (Si) and Germanium (Ge) are the most commonly used elemental semiconductors.

Gallium Arsenide (GaAs) is a compound semiconductor, used in high-speed devices like LEDs and lasers.

These materials have 4 valence electrons and form crystalline structures that can conduct electricity under specific conditions.

Energy Bands in Solids

Types: Valence Band, Conduction Band, Forbidden Gap

Mnemonic: "Vicky Conducts Funky Grooves"

Breakdown:

• Vicky - Valence Band
• Conducts - Conduction Band
• Funky Grooves - Forbidden Gap

Valence Band: Contains electrons involved in bonding; lower energy band.

Conduction Band: Where free electrons move and conduct electricity.

Forbidden Gap: The energy difference between valence and conduction bands.

• Conductors: No gap or overlapping bands.

• Insulators: Large gap.

• Semiconductors: Small gap (e.g., 0.7 eV for Ge, 1.1 eV for Si).

This concept explains why semiconductors conduct only under certain conditions (like heat or light input).

p-n Junction Diode Operations

Types: Forward Bias, Reverse Bias

Mnemonic: "Forwards Flies, Reverse Replies: No!"

Breakdown:

• Forwards Flies → Forward Bias → Current flies (flows).

• Reverse Replies: No! → Reverse Bias → No current (except leakage).

Forward Bias: p-side connected to positive terminal and n-side to negative. Current flows. Depletion region narrows.

Reverse Bias: p-side to negative, n-side to positive. No significant current, but reverse saturation current flows. Depletion region widens.

This is the working principle behind rectifiers and Zener diodes.

Simple Circuits with Diodes

Types: Rectifier, Zener Diode, Photodiode

Mnemonic: "Ravi Zerox Photon Beams"

Breakdown:

• Ravi - Rectifier
• Zerox - Zener Diode
• Photon Beams - Photodiode

Rectifier: Converts AC to DC using diodes. Half-wave and Full-wave types.

Zener Diode: Special diode used in reverse bias to maintain constant voltage → voltage regulation.

Photodiode: Converts light into current, used in sensors and optical devices.

Transistor Configurations

Types: Common Emitter, Common Base, Common Collector

Mnemonic: "Clever Engineers Build Circuits"

Breakdown:

• Clever Engineers - Common Emitter
•  Build - Common Base
• Circuits - Common Collector

These are three ways to connect transistors in circuits, each with unique characteristics:

1. Common Emitter (CE):

   • Most commonly used.

   • High voltage and current gain.

   • Phase shift of 180°.

2. Common Base (CB):

   • Low input impedance, high voltage gain.

   • No phase shift.

   • Used in high-frequency applications.

3. Common Collector (CC):

   • High input impedance, low output impedance.

   • No voltage gain, used for buffering.