A super introduction to semiconductors for junior and senior high school students: Connecting the world and its mechanisms just by reading
This book answers the simple question, "What is a semiconductor?" with easy-to-understand explanations using diagrams on how semiconductors work, what their role is, and why they are necessary.
It also covers PN junctions, MOSFETs, a "word breakdown diagram" of smartphones, the manufacturing process, the differences between ICs/LSIs/chips, search tips, and a glossary.
The recent shortage of semiconductors has also affected the production of automobiles and game consoles.
In other words, semiconductors are the invisible heart of society.
Let's start by explaining why we should learn this now.
1. What is a semiconductor? (Starting with the etymology)
Materials can be classified into three types based on how easily electricity passes through them: conductors (well-behaved), insulation (hardly pass electricity through), and semiconductors (they can change the way electricity passes depending on the conditions). The key words are band gap and doping.
- Conductor = always-open-gate high-speed (e.g. copper)
- insulation = gate always closed (e.g. glass)
- Semiconductor = gate opening and closing can be control by light, heat, voltage, and doping (e.g., silicon)
2. Where is it used? (A familiar "decomposition of words")
Semiconductors are the "invisible heart" of society, from smartphones, PCs, home appliances, automobiles, medical equipment, and factory equipment.
Smartphone word breakdown diagram (for junior and senior high school students)
Main board (green board) = town of electronic components.
- The black square in the center (PoP): The bottom is the SoC (logic), and the package on top is the DRAM (PoP).
- Under the silver box (shield can): Power supply IC and RF front end
- Black chip next to the camera: CMOS image sensor
- The long, narrow board at the bottom: Charging/audio and power semiconductors
An exploded view of automotive (especially EV) terminology
- Large aluminum box: Inverter (with SiC MOSFET inside)
- Behind the charging port: In-car charger (example of GaN HEMT use)
- Sensors: Camera, millimeter-wave radar, ultrasonic (semiconductors act as the "eyes" and "ears" for each)
3. How does it work? (P-N junction illustration)
P and N blood types: twins with different personalities
The properties can be changed by adding small amounts of impurities (doping): N-type has many electrons, while P-type has many vacant electron seats (holes).
PN junction: An "invisible checkpoint" at the boundary
Illustration of the depletion layer term
- Meet and disappear: Electrons and holes recombine at the boundary → carriers decrease
- A checkpoint is built: At the border depletion layer"Invisible Wall can
- Electric barrier: The internal electric field pushes back, saying "No more can pass through"
Forward direction (P side + N side -): The wall becomes thinner → the water level difference (voltage) pushes out the water, and current flows like a floodgate opening.
Reverse direction (P side - N side +): The wall becomes thicker → the weir becomes higher and almost no water flows.
- Diode = one-way check valve
- LED = Light emitted by recombination in the forward direction (color is determined by band gap)
- Solar cell = Generates electricity by creating carriers using light and separating them in an internal electric field
4. Diodes/Transistors (MOSFETs are "faucets and channels")
MOSFET terminology illustration
OFF: There is a dam between the river (source) and the lake (drain), preventing water (electrons) from passing through.
ON: The gate voltage causes the ground to cave in, creating a channel through which water flows out.
Key point: The gate is insulation and operation simply by pushing (voltage), resulting in low power consumption.
Memo: How to create 0s and 1s (digital)
High/low voltages can be treated as 1/0, and by combining them with MOSFETs, logical computation (NOT/AND/OR) can be performed.
5. Differences in materials (why other materials besides silicon?)
| material | Band gap (eV) | Areas of expertise | Applications |
|---|---|---|---|
| Si | 1.1 | General-purpose | CPU/Memory |
| GaAs | 1.4 | high-speed and high frequency | wireless |
| SiC | 3.3 | High pressure and high temperature resistance | EV/Power Conversion |
| GaN | 3.4 | high-speed /compact | charger/base station |
6. Semiconductor type (logic/memory/ analog /power/sensor)
- Logic: CPU/SoC (computation and control)
- Memory: DRAM/NAND (memory)
- analog: Op-amps, A/D converters, power supply ICs (real-world signals)
- Power: MOSFET/IGBT/SiC/GaN (high power control)
- Sensors: light, temperature, pressure, acceleration, etc.
How industry is created: Measurement (sensor) → Conversion (analog /AD) → Decision (logic) → Drive (power).
Division of roles in the industry: In some cases, there are separate companies that design (fabless) and companies that manufacture (foundries). There are also IDMs that handle everything from design to manufacturing.
7. How is it made? (Pre-process → Post-process)
Ingot → Wafer → Pre-process (thin film, exposure, etching, doping) → Wiring → Post-process (dicing, sealing, inspection).
In high-temperature processes (CVD, oxidation, diffusion, annealing), a difference of ±1°C can affect film quality and yield. CHINO provides high accuracy temperature sensors for semiconductor manufacturing equipment.
8. Differences between ICs, LSIs, chips, and semiconductor elements
- Semiconductor element: A general term for basic components such as diodes and transistors
- IC (integrated circuit): A circuit made up of many elements
- LSI: Large-Scale Integration (VLSI/ULSI)
- Chip/Die: The semiconductor body cut from the wafer (before packaging)
- Package: Protects the chip and has legs for easy use
Synonymous relationship: IC ⊂ LSI (LSI stands for "large-scale IC") / Chip = Die (the body before packaging).
9. Technology Trends (Miniaturization, Chiplets, Power Semiconductors)
- Miniaturization + GAA: Faster and more energy-efficient with shorter water channels
- Chiplets: Small towns for specific purposes that can be connected later
- Advanced packaging: 2.5D/3D shortest route
- SiC/GaN: A revolution in power generation with high voltage and high temperature resistance
10. The people who made semiconductors
The story behind the birth of the transistor (1947)
- Three researchers at Bell Labs
- Evolution from "point contact type" to "bonded type"
- From vacuum tubes to the transistor revolution
Moore's Law and Intel's Challenge
- Gordon Moore's prophecy in 1965
- Will the "doubling in two years" really continue?
- The limits of miniaturization and the challenge of new technologies
11. The Amazing World of Semiconductors
Semiconductors in smartphones
- iPhone: Approximately 20 billion transistors at work
- Number of calculations per second: Approximately 1 trillion
- power consumption: 1/100 or less of an incandescent bulb
Incredible precision in the manufacturing process
- Number of chips per wafer: Hundreds
- Precision: 99.9999%
- Clean room: 10 particles of 0.5µm or larger per cubic meter of air
12. The Future of Semiconductors and Your Future
Semiconductor technology in 10 years
- Semiconductors for quantum computers
- Brain-like computers (neuromorphic)
- Optical semiconductors increase data high-speed
How to work in the semiconductor industry
- Design Engineer: The person who thinks about circuits
- Process Engineer: development manufacturing methods
- Equipment Engineer: Builds manufacturing equipment
- Sales and Marketing: Delivering technology to the world
If you study at university
- Department of Electrical and Electronic Engineering / Department of Materials Engineering / Department of Physics / Department of Chemical Engineering
13. Common stumbling points
"Are current and electrons moving in opposite directions?"
- current is "+ to -", electrons are "- to +"
- The problem of historical definition
- Understand the difference between actual behavior and conventions
"Why does P-type conduct electricity even though it has fewer electrons?"
- Holes are also carriers that carry electric charge
- The movement of "vacant electrons" creates current
- Explained using the analogy of passing the baton in a relay race
14. Q&A: What is a semiconductor? How does it work? What is its role? Why? (Search keywords supported)
- Q1. What is a semiconductor? (Even a junior high school student can understand)
- It has properties between those of a conductor and an insulation, and can change the way it passes through depending on the conditions. This allows it to be used for switches and calculations.
- Q2. How semiconductors work (very roughly)
- An invisible wall (depletion layer) is created at the boundary (PN junction), and current changes like the opening and closing of a floodgate depending on the direction of the voltage.
- Q3. The role of semiconductors (what are they used for)
- Smartphones, automobiles, electricity, medical care... they are used in the entire process of measuring → thinking → acting.
- Q4. Why is it necessary? (Why is it still evolving?)
- The key to energy conservation, safety, and convenience. Because it supports smaller, smarter, and more efficient products.
15. Search Tips & How to Identify Information (For research studies by high school and junior high school students)
Recommended search terms
- "What is a semiconductor?" "How does a semiconductor work?" "What is the role of a semiconductor?" "Why is a semiconductor used?"
- "PN Junction Made Easy," "MOSFET Mechanism Illustrated," "Semiconductors for Junior and Senior High School Students"
Reliability Check
- Check the publication date, source, and author affiliation. Be careful of overly inflammatory language.
16. Mini-Glossary
- band gap
- The difference between the valence band and the conduction band. The larger the difference, the higher the withstand voltage and temperature.
- doping
- Properties adjusted with trace amounts of impurities (P/N type).
- PN junction/depletion layer
- An invisible wall that forms at the boundary. Its thickness changes with voltage.
- MOSFET / CMOS
- The gate voltage creates a channel and allows/stops current.
- IC / LSI / Chip
- IC = Integrated Circuit, LSI = Large Scale IC, Chip = Main body before packaging.
- Fabless / Foundry / IDM
- Design only / Contract manufacturing / Integrated company.
17. Connecting the Real World: Measurement and control Perspectives
In factories, the loop of measurement (sensor) → conversion (analog /AD) → judgment (logic) → drive (power) is vital. Temperature stability is directly linked to the yield rate and energy efficiency.
Summary materials for those who don't have much time
What did you think? CHINO Corporation offers everything from process temperature monitoring to equipment control sensors.
If you have any problems with semiconductor temperature measurement, please feel free to contact us.
An excerpt from this page is available here.
Download excerpt
