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

What this unit is about?

  1. Mar 30, 2010 #1
    "a silicon cristal is doped with 1000000000000000000 [tex]cm^{-3}[/tex] atoms of antimon"

    how does [tex]cm^{-3}[/tex] represents a number of atom

    why not just say
    "a silicon cristal is doped with 1000000000000000000 atoms of antimon"
     
  2. jcsd
  3. Mar 30, 2010 #2

    MATLABdude

    User Avatar
    Science Advisor

    That's a concentration. There are 1 x 10^18 atoms of antimony per cubic cm. You need doping level (concentration) in order to calculate semiconductor operation.
     
  4. Mar 30, 2010 #3
    why cubic cm is cm with power of -3
    and not power +3
    ?

    cubic is power +3
     
  5. Mar 30, 2010 #4

    MATLABdude

    User Avatar
    Science Advisor

    It is! If you know exponents, cm^-3 is the same thing as 1/cm^3. Something per cubic cm, as we say.
     
  6. Mar 30, 2010 #5
    aaaaahhhhhhhhhhhhhhhh thanks
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook