Introduction to semiconductors

Chapter Introduction to semiconductors

Teach Yourself Electricity and Electronics Third Edition Book
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Summary of Contents

Teach Yourself Electricity and Electronics Third Edition Book

  • 19CHAPTERIntroduction tosemiconductorsSINCE THE SIXTIES, WHEN THE TRANSISTOR BECAME COMMON IN CONSUMERdevices, semiconductors have acquired a dominating role in electronics. This chapterexplains what semiconducting materials actually are.You’ve learned about electrical conductors, which pass current easily, and about in-sulators, which block the current flow. A semiconductor can sometimes act like a con-ductor, and at other times like an insulator in the same circuit.The term semiconductor arises from the ability of these materials to conduct “parttime.” Their versatility lies in the fact that the conductivity can be controlled to produceeffects such as amplification, rectification, oscillation, signal mixing, and switching.The semiconductor revolution It wasn’t too long ago that vacuum tubes were the backbone of electronic equipment.Even in radio receivers and “portable” television sets, all of the amplifiers, oscillators,detectors, and other circuits required these devices. A typical vacuum tube ranged fromthe size of your thumb to the size of your fist.A radio might sit on a table in the living room; if you wanted to listen to it, you wouldturn it on and wait for the tube filaments to warm up. I can remember this. It makes mefeel like an old man to think about it.Vacuum tubes, sometimes called “tubes” or “valves” (in England), are still used insome power amplifiers, microwave oscillators, and video display units. There are a fewplaces where tubes work better than semiconductor devices. Tubes tolerate momentaryvoltage and current surges better than semiconductors. They are discussed in chapter 29.Tubes need rather high voltages to work. Even in radio receivers, turntables, andother consumer devices, 100 V to 200 V dc was required when tubes were employed.This mandated bulky power supplies and created an electrical shock hazard.359Copyright © 2002, 1997, 1993 by The McGraw-Hill Companies. Click here for terms of use.