Understanding Diode Conductivity: The Role of Conduction and Valence Electrons

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Discussion Overview

The discussion focuses on the conductivity of diodes, particularly the roles of conduction and valence electrons under different bias conditions. Participants explore the mechanisms behind current flow in diodes, the effects of forward and reverse bias, and the interactions between electrons in different regions of the diode.

Discussion Character

  • Technical explanation
  • Conceptual clarification
  • Debate/contested

Main Points Raised

  • One participant states that a diode becomes conductive at a forward-bias of about 0.7V, with current in the n region formed by conduction electrons and in the p region by valence electrons moving toward the positive side of the power source.
  • Another participant explains that a positive voltage on the n region pulls free electrons away from the junction, while a negative voltage on the p region pulls holes away, leading to a lack of charge carriers at the junction and minimal current flow.
  • There is a question about whether conduction electrons in the copper cord can move into the p region, with one participant asserting that they can, referencing metal-semiconductor junctions.
  • Another participant expresses uncertainty about the nature of the junction, suggesting a need for further clarification regarding metal-semiconductor interactions and band theory.

Areas of Agreement / Disagreement

Participants express differing views on the behavior of conduction electrons at the junction and the implications of biasing the diode. The discussion remains unresolved regarding the specifics of electron movement and the characteristics of the junction.

Contextual Notes

Participants reference concepts such as band theory and metal-semiconductor junctions, indicating potential complexities in understanding the behavior of electrons in diodes. There are unresolved aspects related to definitions and the nature of the junctions discussed.

xunrichard
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As we are told in the books，a diode can be conductive by a forward-bias of about 0.7v.
Thus,current through the n region is formed by the conduction electrons（free electrons in the conduction band） toward the junction.But in the p region,current is formed by the valence electrons from holes to holes toward the positive side of the power source.Obviously,the conduction electrons from the n region can easily become the valence electrons in the p region and the valence electrons in the p region can easily become conduction electrons so they can move into the copper cord（as we suggest）which is between the positive side of the power source and the p region.
So here is the question：why a diode can not be conductive by a reverse-bias voltage?
Can the conduction electrons in the copper cord move into the p region? If not,why?
 

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Positive voltage on the N region pulls free electrons away from the junction.

Negative voltage on the P region pulls holes away from the junction. Alternately, you can think that the negative voltage pushes electrons into fill the holes by the junction.

The junction is left barren of any charge carriers, and only the barest trickle of current can flow through.
 
Jiggy-Ninja said:
Positive voltage on the N region pulls free electrons away from the junction.

Negative voltage on the P region pulls holes away from the junction. Alternately, you can think that the negative voltage pushes electrons into fill the holes by the junction.

The junction is left barren of any charge carriers, and only the barest trickle of current can flow through.

Thank you! You are right. I think I got it.Thank you.
 

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