Class notes 4/9: Semiconductors and MOSFETS Creative Commons License

In general, diodes have an appreciable current at .7 Volts. K is boltzman’s constant M is normally between 1 and 2 for whatever we’re working with Column 3a is known as the acceptors Current flows from p to n When vd>0 the depletion redion width decreases and the current voltage relationship is exponential ^forward bias When vd<0 the depletion region width increase and the current becomes a constant –is (saturation current) ^reverse bias Silicon dioxide is a good insulator http://computer.howstuffworks.com/diode2.htm - describes semiconductors and diodes quite well See his chart of a vds MOS (metal oxide semic onductor) ---he did an ntype (pictures below) http://en.wikipedia.org/wiki/MOSFET#Metal.E2.80.93oxide.E2.80.93semiconductor_s tructure – describes MOS – below picture from this website Questions: 1) why is the source connected to the body (substrate). 2) why must the gate overlap the drain and source? Otherwise the n chanel wouldn’t extend from n to no MOS creates an electron channel, or n channel Vgs0 provided vds>0


Document Info

Posted By:
DJ Sharkey
Date:
Wednesday, April 9, 2008
School:
Duke University
Class:
ECE 27L
Tags:

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