A diode stops current flow by creating a depletion region when reverse biased, which acts as an insulator.
Here's a more detailed explanation:
When a diode is reverse biased (meaning the positive terminal of the voltage source is connected to the N-type material and the negative terminal to the P-type material), the following occurs:
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Charge Carrier Movement: The holes (positive charge carriers) in the P-type material are attracted to the negative terminal of the voltage source, and the electrons (negative charge carriers) in the N-type material are attracted to the positive terminal.
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Depletion Region Widening: This movement of charge carriers away from the junction between the P and N materials causes the depletion region (a region with very few free charge carriers) to widen.
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Increased Resistance: The widening depletion region acts as an insulator, significantly increasing the resistance to current flow. Essentially, there are no charge carriers available in the depletion region to conduct electricity.
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Barrier Potential: The applied reverse voltage adds to the built-in potential barrier of the diode, further hindering the flow of majority carriers.
In summary, a diode in reverse bias stops current flow because the applied voltage pulls the charge carriers away from the junction, creating a wider depletion region that acts as an insulator. This prevents the flow of current unless the reverse voltage exceeds the diode's breakdown voltage, which can damage the diode.
