Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

P-n junction

  1. Nov 23, 2005 #1
    Is a semiconductor with a p-n junction considered a transistor or just a diode? If it is just a diode, are transistors always triodes?
     
    Last edited: Nov 23, 2005
  2. jcsd
  3. Nov 23, 2005 #2

    Danger

    User Avatar
    Gold Member

    Not my area, but... as far as I know a transistor has to be at least a triode because you need to input the control voltage.
     
  4. Nov 23, 2005 #3

    Gokul43201

    User Avatar
    Staff Emeritus
    Science Advisor
    Gold Member

    It is a diode, not a transistor. It has greater conductivity in one direction than the other.
    A triode is a vacuum device that works essentially like a transistor. It is not a solid state device.

    A transistor must have three terminals. The idea is that by applying a (gate) voltage at one of the terminals, you can control the current flowing between the other two. The BJT is constructed essentially by sticking a pair of p-n junctions together, making sure the middle layer (the base) is really thin.
     
  5. Nov 23, 2005 #4
    Oh, ok. Thanks!
     
  6. Nov 23, 2005 #5

    Danger

    User Avatar
    Gold Member

    Thanks for the clarification on the triode, Gokul. I always thought that it was just anything with 3 leads.
     
  7. Nov 23, 2005 #6

    Gokul43201

    User Avatar
    Staff Emeritus
    Science Advisor
    Gold Member

    Ever worked with tube-amps ? People still like to build their amplifiers out of triodes for better sound quality.
     
  8. Nov 23, 2005 #7

    Danger

    User Avatar
    Gold Member

    I've never worked with any electronics. As my post should tell you, I know almost nothing about it. :redface: The closest that I got was changing burned-out tubes in my TV (yes, I'm that old :grumpy: ). I've heard very often that audiophiles pay big bucks for tube amps because they provide a 'warmer' sound. I guess the closest analogy that I can think of is that of a very good painting (tubes) as opposed to a photo (solid-state).
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Have something to add?