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A Semiconductor can be a conductor

  1. Oct 22, 2017 #1
    I have Semiconductor at my home. I had to use a Semiconductor as junction of electrical current. Current at the junction could be so big if I shoot a sun light from lens and mirror to a Semiconductor. What happen about my experiment? What is it a fotoelectric effect?
  2. jcsd
  3. Oct 22, 2017 #2


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    This is not a "photoelectric" effect.

    Look at the standard band diagram of an intrinsic semiconductor:

    There is a "gap" in the energy band. The electrons in the conduction band are able to move (just like in an ordinary conductor). At temperature 0K, the valence band is full, the conduction band is empty. At a typical, room temperature, the heat is often enough to cause a small population of electrons to jump from the valence band into the conduction band. Thus, this material becomes a conductor (a poor conductor). If you warm it up even more, more electrons will populate the conduction band, and thus, it becomes more conducting.

    Without knowing the material you are using as your "semiconductor", it is hard to know if the energy from light itself is sufficient to cause more electrons to jump into the conduction band, or if the light causes the semiconductor to warm up, and thus, it is the thermal energy that causes more conduction electrons.

  4. Oct 22, 2017 #3
    Now I know, it's not fotoelectric effect but it's a conversion thermal energy to kinetic energy of the electrons to jump.
  5. Oct 22, 2017 #4
    It's not conversion light energy to kinetic energy of the electrons to jump
  6. Oct 22, 2017 #5


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    It is not directly kinetic energy, and you shouldn't take the "jump" too literally. If you heat up a semiconductor more electrons will be in the conduction band, but this is rarely wanted in applications.
  7. Oct 22, 2017 #6
    Thank you very much
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