Diodes on Zero Volts

Discussion in 'General Electronics Chat' started by jrv9090, Feb 19, 2015.

  1. jrv9090

    Thread Starter New Member

    Nov 26, 2014
    Hi fellows,

    I am trying to understand what happens when the two terminals of a diode are shorted.

    First let me tell my understanding, the diode in open circuit conditions has a depletion region at the junction. This depletion region creates a electric field because of the ionic nature of matter present at the junction. This field in turn forms a voltage potential (ppl loosely speak this voltage to be 0.7V for P-N junction diodes. I am not sure of the exact value though).

    Now my question is, if I short the diode terminals, the voltage difference should drop down to zero. Does it mean the field collapses and there is no more depletion region????? (OR) Does the depletion region potential acts kind of a battery and drives current through the terminals, then make the potential zero?????

    I think the possibilities I listed looks crazy and not convincing but I am unable to pin point the exact process as to what happens when the diode terminals gets shorted. Pls let me know what happens to the depletion region under this condition also...
  2. Kermit2

    AAC Fanatic!

    Feb 5, 2010
    nothing happens. the electric field is still present but while the short exists, each region sees an opposite potential present at both side boundaries of the region and the net result is no movement of charges. when short is removed, charges migrate until the local potential in the boundary region balances out. again end result is a neutralized field due to charges balancing.
  3. MikeML

    AAC Fanatic!

    Oct 2, 2009
    Minor nit. Since there is likely light impinging on the diode, a small electric current will flow through the short...