Semiconductor

Introduction

A semiconductor is a substance that has electrical conductivity between a conductor (like copper) and an insulator (like rubber).
Its conductivity increases with temperature or impurity doping.
Semiconductors are key to modern electronics, including transistors, diodes, solar cells, and LEDs.

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Characteristics of Semiconductors

• Conductivity lies between conductors and insulators
• Made of metalloids like Silicon (Si) and Germanium (Ge)
• Conductivity increases with temperature (opposite of metals)
• Electrical behavior can be altered by doping (adding impurities)
• Form the backbone of electronics, solar tech, communication devices

📝 PYQ (BPSC): Which element is used in computer chips? → Silicon
📝 Expected MCQ: Which material has intermediate conductivity? → Semiconductor

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Types of Semiconductors

✔️ Intrinsic Semiconductors

• Pure form (e.g., Silicon, Germanium)
• Conductivity is low in pure state
• Conducts electricity when heated

✔️ Extrinsic Semiconductors (Doped)

• Conductivity improved by adding impurities
• Types:
  • n-type: Extra electrons (e.g., Phosphorus in Si)
  • p-type: Electron holes (e.g., Boron in Si)

📝 Expected MCQ: Which doping produces extra electrons? → n-type semiconductor
📝 Expected MCQ: Example of intrinsic semiconductor? → Silicon

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Applications of Semiconductors

💻 Electronics

• Transistors, Diodes, Integrated Circuits (ICs) are made from semiconductors
• Bihar students in ITI/Polytechnic use Si-based chips in practicals

🔆 Solar Cells

• Made from Silicon, used in India’s Rooftop Solar Mission
• Bihar Renewable Energy Department promotes solar street lights, solar panels using semiconductors

💡 LEDs & Sensors

• LEDs use semiconductors to convert electricity into light
• Motion sensors and automatic lights (used in smart Bihar projects)

📱 Communication

• Mobile phones, laptops, TVs – all run on semiconductor-based chips

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Bihar-Based Relevance

• Skill Development: Electronics taught in Bihar’s ITI colleges, Polytechnics, and CSVTU Tech hubs
• Solar Push: Bihar’s Renewable Energy Policy uses semiconductor solar modules in rural electrification
• Digital Learning: Devices distributed under Bihar ICT schemes run on Si-based chips

📝 Expected MCQ: Which policy in Bihar promotes solar cell use? → Bihar Renewable Energy Policy

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Semiconductor vs Conductor vs Insulator

📝 Expected MCQ: Which of these increases conductivity with heat? → Semiconductor

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Common Elements Used

• Silicon (Si) – Most widely used
• Germanium (Ge) – Used in special sensors
• Gallium Arsenide (GaAs) – Used in solar cells, LEDs
• Doping Elements: Phosphorus, Boron, Arsenic, Gallium

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PYQs + Expected MCQs

📝 PYQ (BPSC): Which material is used in computer chips? → Silicon
📝 Expected MCQ: What is the nature of a semiconductor? → Intermediate conductor
📝 Expected MCQ: Doping with Boron creates? → p-type semiconductor
📝 Expected MCQ: Semiconductor used in solar cell? → Silicon
📝 Expected MCQ: Which of the following is a semiconductor? → Germanium

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Quick Revision Points

• Semiconductors = moderate conductivity, improves with heat
• Silicon, Germanium → Intrinsic semiconductors
• Doping creates n-type or p-type semiconductors
• Used in: transistors, diodes, solar cells, LEDs
• Bihar’s solar mission uses semiconductor panels
• Skill training in Bihar covers semiconductor applications

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Sources Used

• NCERT Class 10 Science – Electricity & Sources of Energy
• Lucent GK – Physics Section
• Drishti Science Quick Book
• EduTeria + Ghatna Chakra PYQs (BPSC, DPRO, CDPO)
• Bihar Renewable Energy Development Agency (BREDA)
• Skill Development Reports – Bihar ITIs and Polytechnic Colleges
• Ministry of New and Renewable Energy – Solar Mission Reports