How do transistors really work?

[ranger]

I'm looking for a good tutorial that explains how a transistor works. My textbook doesn't do a good job. I searched the internet and found this. But I'm questioning the validity of this document. He really mentions some strange things contradicting what I had previously known. I would be grateful if someone could confirm whether it is valid or not. Its only two pages
I feel so ashamed - 2 yrs in college and I don't how a transistor really works. All I know is formulas.

--thank you.

 

[berkeman]

Hi Ranger,

You're asking a very good question. Getting an intuitive feel for how charges flow and how junctions form and move is really important for working with semiconductors at more advanced levels. I still remember the night in the library during my undergrad when I finally started getting it -- I literally got goose bumps reading the chapter about how the junctions in a BJT worked to generate current gain. Great stuff.

I googled transistor tutorial, and got lots of great hits. Skip the first one (lame) and maybe start browsing at the second hit to see if some of these are useful. What textbook are you using for learning about BJTs?

http://www.google.com/search?hl=en&lr=&q=transistor+tutorial

 

[ranger]

What textbook are you using for learning about BJTs?

I'm using - Introductory Electronic Devices and Circuits by Robert T. Paynter.
http://wps.prenhall.com/chet_paynter_introduct_7

 

[abdo375]

First I must clarify that the transistor is a very broad subject and it's unlikely that you will find a single books that encapsulates it all.

That being said I guess your looking for a book to explain the physical structure of the transistor
I'd first recommended "Microelectronic circuits by Sedra Smith" but this is a circuit's book, it only has two useful chapters, one for the BJT and the other for the MOSFET, after you finish reading these two chapters you will have a semi-clear idea of how transistors work on the physical level, next I'd recommend "Solid state electronic devices by ben G. streetman" it's a good book to take you to the next level.
Please note that I've assumed that you have some basic knowledge of quantum mech. and PN junctions.

 

[Lundy]

I did read the article in question and it was a nice read. The author does explain transistors (and the fundamentals of electronics for that matter) in a much different way, but I think it's a good thing. Nothing I read contradicted any of what I know, which doesn't say a whole heck of a lot, but I hope being a Senior at Penn State in Electrical Engineering gives me at least a tidbit of credibility. :)

 

[chroot]

Electronics textbooks are not going to really teach you how a transistor works. They are mainly concerned with models of the transistor which can be used to solve circuits.

What you want is a semiconductor device physics textbook, like Neamen.

- Warren

 

[abdo375]

They will at least give a general understanding of how it works,
I doubt that explaining the short channel length effect will give you that kind of view of the subject, although Semiconductor Physics and Devices is an excellent book it tends to make you forget the basic idea behind the transistor.

 

[mugsby]

i have semiconductor physics by sze, way over my head. so far I've just stayed with knowing how majority and minority carriers work with there substrate.(still a noob though)

 

[ranger]

I showed the article in question to my professor and he said it is wrong. The article claims that a (BJT) transistor is a voltage controlled device. My professor said the transsitor is a current controlled device. My prof. also put down the claim that "current does not flow". I am confused

 

[berkeman]

I showed the article in question to my professor and he said it is wrong. The article claims that a (BJT) transistor is a voltage controlled device. My professor said the transsitor is a current controlled device.

Well, the base current is determined using the diode equation, which relates Ib to Vbe. The transistor gain equations (see the Ebers-Moll model, for example) relate Ic to Ib. So it just depends on how you want to think about the equations...

 

[ranger]

So it just depends on how you want to think about the equations...

Its the way my professor said it. Its as if he scoffed at it. The way the author of the article presents his points is convincing. I can see nothing wrong with a BJT being voltage controlled. But I guess its like you said- its the way you look at it.